- What Kind of Light Do Plants Need? All About Indoor Grow Lights
- Fluorescent Light Bulb Types
- Fluorescent Light Bulb Colors
- Bulb Brightness
- Making Your Decision
- Shop our Complete Selection of LED Tube Replacements
- Currently, there are four types of options available in the market:
- T8 Electronic Ballast Compatible LED Fluorescent Replacement Tubes
- Hybrid (T8 Electronic Ballast Compatible / T8 or T12 Ballast Bypass LED) Fluorescent Replacement Tubes
- Universal (T8 Electronic or T12 Magnetic) Ballast Compatible LED Fluorescent Replacement Tubes
- How To Choose Fluorescent Grow Lights For Your Farm
- When should you use fluorescent grow lights?
- Choose a high-output fluorescent
- So when should you use a T12 bulb?
- How much fluorescent light is enough?
- Learn more about indoor crop lighting
- Light Requirements for Plants
- How Much Light Do Plants Need?
- Defining light, from dense shade to full sun
- Signs of too much, too little sun
- Fluorescent Light And Plants: Lighting Options For Indoor Gardening
- About Fluorescent Light and Plants
- Determining Lighting Requirements Indoors
- Fluorescent Lighting Options for Indoor Gardening
- Easy Beginner Grow Cannabis Guide w/ CFL Grow Lights | How to Grow Marijuana
- What Fluorescent Bulbs for Growing Flowering Plants (Marijuana, tomatoes, etc)?
- What Kind of Fluorescent Bulbs for Plants that Don’t Flower?
- Best Fluorescent Grow Lights
What Kind of Light Do Plants Need? All About Indoor Grow Lights
On days when you can barely remember the sun, it can be hard to imagine your plants—indoor or out—ever achieving full bloom. Your outdoor plants may manage just fine with the diffused level of light they receive, especially in the summer, but sometimes indoor plants need a little more help to properly photosynthesize.
Enter the grow light. If your indoor space lacks natural light, either in the winter or year-round, these specialty lamps or light bulbs can provide your indoor plants with the type of light they need to grow and thrive.
How to tell if your plant isn’t getting enough light
If you are new to cultivating indoor plants—and sometimes even if you aren’t—it can be hard to tell what ailment your plant is suffering from. You will be able to tell if your indoor light is insufficient for your plants if they exhibit some or all of the following symptoms:
- Leggy or spindly stems.
- New growth is stunted (such as small leaves).
- Lower leaves die off.
- Reduced or no flowering.
- Pale colour or lack of variegation on new growth—be careful though, for shade-loving plants such as Calatheas, pale colour indicates that it is getting too much
If you don’t receive a lot of natural light, don’t worry—your indoor plants can still thrive. Indoor grow lights will supplement the natural light you do receive, giving your plants the boost they need to photosynthesize.
Full spectrum vs. red & blue grow lights
Most grow lights are either full spectrum, which means the light they emit spans the entire electromagnetic spectrum (similar to the sun), or they provide particular tones that plants find the most useful for growing—specifically red and blue light. Red and blue light are best paired together, as they provide more even growth levels when combined.
PRO TIP: “Red” or “blue” light refers to more than just the colour of the light bulb, though you may find some of the light bulbs do give off red, blue, or pink illumination. The colour designation refers to the visible light wavelength. The different wavelengths of light affect plants in different ways:
- Red light – “tell plants how many leaves to make and how big to make them”
- Blue light – “control how plants respond to a daily cycle of light… tell plants when to flower.” (McCallister, A. 2018)
It’s also important to remember that different types of plants require different ratios of red to blue lighting. What works for one type of plant will not necessarily work for another. You may need to do some research or experiment with how much blue vs red light each plant type needs to see optimal results. Alternatively, you can select a full-spectrum bulb, which most closely resembles the sun.
If you’d prefer not to have the ambience from the purple-pink tones of a red/blue light, daylight coloured bulbs with a high correlated-colour temperature (CCT) rating can also provide you with enough lighting to facilitate growth. However, if you are very serious about indoor growing, you will want to select a clearly-labelled full spectrum bulb, which provides the closest facsimile to the sun.
Full spectrum lamps are best for plants that need lots of light, such as:
- Culinary herbs
- Starter plants or seedlings
- Carnivorous plants
PRO TIP: For starter plants and seedlings, place the lamps 2-4 inches from the plants.
For well-established plants, place the lamps 1-2 feet away from the plants.
Types of grow light bulbs
Grow lights are available in all different types of light bulbs from incandescent to fluorescent to LED. So how do you know which bulb is best suited to growing bulbs?
Incandescent light bulbs
Typically, incandescent and halogen lights are not recommended as grow lamps because, while they do often offer full spectrum lighting, they operate at a very high temperature that can easily damage foliage. They are also inefficient in terms of energy usage, and are being phased out by governments worldwide. In short, there are cheaper, more effective, and more efficient alternatives to incandescent grow lights.
Fluorescent light bulbs
Fluorescent lights are often used as grow lamps because you can easily find tubes that have full spectrum lighting or which are specifically designed for growing plants. They also give off less heat and are more energy efficient than incandescent bulbs, meaning they require fewer watts to put out the same amount of light.
PRO TIP: If you just have a few plants and don’t want or don’t have the space for a full grow lamp setup, compact fluorescent (CFL) bulbs can be used as grow lights as well. For the best results, make sure they offer full spectrum lighting. Speak to a gardening expert about which type of bulb would work best with the plants you are growing.
LED light bulbs
Thanks to their energy efficiency, longevity, and the low level of heat they emit, LEDs have quickly become a popular light bulb option for growing plants. You can also fine-tune the colour wavelength put out by the bulb, so a single LED bulb can be made to produce both red and blue wavelengths for optimal growing, negating the need for multiple light bulbs.
While the initial cost of these lamps was fairly prohibitive, the price is continuing to drop as their popularity increases and manufacturers become more familiar with their production. Now, there are many different colours, types, and shapes of LEDs available, but for optimal growth results, look for LEDs that are specifically marketed as horticultural or grow-lights.
How much light do your plants need?
It’s easy to assume that the more light your plant gets, the better they will grow, but there is actually a saturation point after which your plant will no longer get any benefits from receiving light. After all, plants need rest to maintain a healthy growth process, and periods of darkness are essential to this.
PRO TIP: The best way to stay on top of the amount of light your plant is getting is to install a timer so that it turns on and off at the correct time each day.
The amount of light needed is different for each type of plant, so follow the care instructions that come on the plant marker in the pot or do a bit of research about the specific types you have to ensure it is receiving optimal growing conditions. Follow these guidelines as a general rule:
Type of plant
Hours of light per day
|Day-neutral||~12 hours||Foliage plants (ex. ferns, hostas), geraniums, coleus, African violets|
|Short-day||12 hours or less||Chrysanthemums, kalanchoe, azaleas, begonias|
|Long-day||14-18 hours||Vegetable seedlings, garden flowers, cacti, hybrids|
Grow lights are a great way to supplement natural lighting and cultivate indoor plants year-round. While they aren’t exactly a match for a sunny day outside (yet!), they will help your plants grow even if you have poor natural lighting. For optimal growing conditions, make sure you:
- Select the right type of light bulb for the job (full spectrum or red/blue)
- Research how much light your plants need
- Position the lamp the correct distance from the plant(s)
- Connect the lamp to a timer so that your plants receive the optimal amount of light each day
SHOP OUR COMPLETE SELECTION OF PLANT GROW LIGHTS
Most fluorescent light bulbs process energy in the same way to produce light; however this doesn’t mean that all fluorescent lights are the same. The differences are generally defined by the color and brightness the bulbs emit, the projected length of time the bulb will function, and the diameter and length of the bulb.
Fluorescent Light Bulb Types
Fluorescent light bulbs have traditionally been a 24-inch, 36-inch or 48-inch 1 ½-inch diameter tube with two pins on each end. Today, there is a wide variety of different types of fluorescent light bulbs — in a variety of lengths and diameters.
The diameter of the tube is described in eighths of an inch. There are twelve eighths in 1 ½ inches, so a T-12 fluorescent lamp is 1 ½ inches in diameter.
Some of the most common fluorescent light bulbs on the market include:
Fluorescent Tube and Circline Lamps
Tubes and circline bulbs are often used for industrial applications. The light emanating from these bulbs can be distinctive, making them less popular for residential use.
- T-12: A T-12 has a diameter of 1½ inches. This is the most common diameter of tube-shaped light bulbs. It is usually bi-pin and it does not require a starter. It is available in a variety of lengths including a 15-inch (14-watt), an 18-inch (15-watt), a 24-inch (20-watt bulb), as well as a 36-inch and a 48-inch bulb.
- T-8: The T-8 tube is in the process of replacing the T-12. It has a 1-inch diameter, it is more energy-efficient and it gives off more light than the T-12. It is available in a variety of lengths including a 12-inch (13-watt), a 15-inch (14-watt), and an 18-inch (15-watt).
- T-5: One of the benefits of the T-5 tubes is that it is more efficient than the T-8 and is currently used in some commercial locations and throughout Europe.
- U-tube: A U-tube is a tube bent in half to form a “U” shape. A 48-inch bulb is bent into a U-tube bulb that is around 22 to 23 inches long and is brighter than a 23 inches tube bulb.
- Circle tube: Circle tubes are available in many sizes, but are generally between 6 inches to 16 inches in diameter and will have a 4-pin connector.
Compact Fluorescent and Screw-Socket Bulbs
These bulbs are the ones most commonly used for residential applications. The light from these bulbs is often engineered to mimic the light of an incandescent bulb.
- Miniature bi-pin sockets: The bulbs to fit these sockets are 5/8-inch in diameter. They are usually 6, 9, 12 or 21 inches long with wattages of 4, 6, 8 or 13 watts respectively.
- Compact fluorescent light (CFL): A CFL bulb is essentially a fluorescent tube that has been reduced to the size of a pencil and then folded or twisted into the shape of a light bulb. It has a screw socket so it can easily screw into a lamp socket. It is more energy-efficient than an incandescent bulb, but not any more energy-efficient than a tubular fluorescent lamp. Compact fluorescent bulbs have a more pleasing color than a tube-shaped fluorescent bulb. Some have electronic ballasts.
- Screw-in bulbs: Often considered the most popular energy-saving light bulbs, they can fit almost any table lamp or light fixture. They cannot be dimmed.
- NEOLITE™ low-mercury: NEOLITE™ bulbs are some of the smallest CFLs available, so they fit in most lamp sockets. The bulb is ENERGY STAR qualified and contains only one milligram of mercury, less than half the mercury of other brands. It also contains led-free solder and glass. It is a bright bulb (70 lumens per watt), has excellent color and a 10,000-hour rated life.
Special-Use Fluorescent Bulbs
To meet consumer demand for more versatility in fluorescent bulbs, manufacturers have developed a wide array of specialty bulbs to suit various unique occasions.
- Floodlights: Fluorescent floodlights use only about 25% of the energy used by regular incandescent floodlights. They also produce less heat. They can be used in recessed can fixtures and track lighting. They cannot be dimmed.
- Dimmable lights: These bulbs offer energy savings and they can be dimmed to 20% of their full light output.
- Decorative torpedo bulbs: Decorative light bulbs are an energy-saving alternative to incandescent decorative bulbs for chandeliers and light fixtures.
- Colored light bulbs: Restaurants, bars, and nightclubs are the most common places to find colored fluorescent light bulbs. They are available in a wide range of colors including red, green, blue, yellow and pink. They have a long life.
- GE 2D bulbs: This pretzel-shaped General Electric bulb has been around since the early 1990s. They are commonly used in torchiere lamp fixtures and table lamps.
- 3-way bulbs: A compact fluorescent 3-way bulb saves energy and lasts much longer than incandescent 3-way bulbs. They can be used in any lamp with a three-way switch. They cannot be used in touch lamps.
- GU24 Twist and Lock bulbs: Part of a new generation of compact fluorescent bulbs, the GU24 allows you to change the wattage of the bulb without changing the fixture. The bulb can be used in the Line Voltage Socket (LVS) that is commonly used on today’s modern ENERGY STAR light fixtures.
Fluorescent Light Bulb Colors
The color of a fluorescent light bulb comes from a powdery coating of mixed phosphors inside the tube. The mixture of phosphors determines the color given off by the light bulb. Fluorescent light bulbs come in many colors of white:
- Daylight: Daylight bulbs casts a blue tone.
- Cool white: This is the most commonly used color in commercial settings. It has a slightly bluish color. It is not recommended for residential use because it has a distortion that makes colors look washed out.
- Warm white: Warm white bulbs are recommended for residential use. They have a slightly pinkish color.
- Full spectrum: A full spectrum bulb shows the truest color and is brighter than the cool white or warm white bulbs.
A brand new fluorescent light bulb takes a few hours to achieve maximum brightness. The bulb’s brightness will start to decline from that point on. The common 48-inch, 4-watt cool white fluorescent tube starts with a brightness of 3,250 lumens, the measurement for the brightness of light. Within six hours, the brightness of the bulb will have declined to an average of 2,960 lumens.
Making Your Decision
The type of fluorescent light bulb you decide to use should be dictated primarily by the area in which you will be using it. Not all fluorescent light bulbs are made equally. They all have their own specialized uses, and these special characteristics should be carefully weighed before making your purchase.
T5 tubes are the latest series of fluorescent lamps. They are offered in standard or high-output (HO) options. There are many differences between T5 lamps and T8 or T12 lamps.
T5 vs. T8/T12
T5 tubes are smaller than T8 and T12 tubes, which allow them to fit into smaller spaces. They are offered in sizes of 2-5 feet in length. T5 lamps are around 40% smaller than T8 lamps and almost 60% smaller than T12 lamps. T5 lamps have a G5 base (bi-pin with 5 mm spacing), while T8 and T12 lamps use a G13 base (bi-pin with 13 mm spacing). Because of a .625-inch bulb diameter, and a mini bi-pin base, the T5 lamp can be used in lower profile areas.
Output and Performance
The T5 lamp has a generally lighter output compared to the T8 lamp. The T5 is offered in color temperatures of 3000K, 3500K and 4100K. They have a color-rendering index (CRI) of 82 or 85, compared to the T8 with a CRI of 75 or 85. The T5 system provides its peak output at 35°C as opposed to the T8 or T12’s peak output at 25°C. This makes the T5 system a better choice in an output over temperature ratio, and a better choice to use for effective lighting in small, and low circulated spaces. With power ratings of 24, 39, 54, and 80, the T5 HO lamp easily beats the T8 or T12 system with over double the output. T5 lamps are generally rated for 20,000 hours, as compared to T8 lamps, which are generally rated for 24,000 hours.
T8 or T12 fixtures must be suspended over 2 feet from the ceiling in order to have effective light. This would be too low for many office buildings where ceilings are rarely high. With T5 lamps, suspension from the ceiling can be as little as 15 inches.
The T5 lamp has a lower mercury content than T8 and T12 lamps, yet it performs with the same or greater efficiency. The lamp has a coating on the inside of its glass wall that stops the glass and phosphors from absorbing mercury. This barrier coating reduces the amount of mercury needed from approximately 15 mg to 3 mg per lamp. Since mercury absorption causes the lamp’s light output to depreciate over its life, the coating helps to keep light levels much closer to initial output (only a 5% depreciation in the first 40% of its life). The lower mercury absorption also keeps the light’s output as strong as its initial output, throughout its life.
T5 vs. T5 HO
The T5 and T5 HO are the same size, but have different outputs. The T5 has an output of 2,900 lumens, similar to the T8 output. The T5 HO has up to 5,000 lumens. With the T5 HO lamps, fewer lamps can be used on projects, which save money due to less maintenance. The high output and thinness of the lamps lets them be available for indirect and shallower lighting. Every T5 HO lamp requires its own ballast, but they are 10-15% less efficacious than normal T5 models. T5 HO ballasts also have many features such as a dimming function, or operating multiple F54 lamps.
T5’s are the first linear lamps to use electronic ballasts only. One T5 ballast can power one or two T5 lamps of any wattage, because they all run at the same current. Their different wattages have the same brightness, which stays the same with any length of the product.
Because of the lamp’s small size and high power, temperature can rise as the lamp dies because of less cathode emission material. This rise in temperature can cause the bulb wall to crack. The T5 ballasts have an “end-of-life circuitry”, which stops the bulb from cracking by shutting off the lamp when there is a rise in voltage.
T5 and T5 HO lamps are increasingly used in offices and industrial areas. The T5 HO system can be used in any area with a ceiling higher than 15 feet, including gymnasiums and warehouses. The T5 offers over 50% more energy saving then a 400 watt metal halide system.
Choosing the right LED fluorescent replacement tubes can be confusing due to the myriad of product types and installation options. We at EarthLED.com have created this guide to assist in the process and help you make the right choice for your specific projects.
Shop our Complete Selection of LED Tube Replacements
The consumer demand for quality LED replacement products fueled recent industry changes, beginning with the introduction of proper safety and light output standards. Much of this development was due to building and facility managers looking for a way to replace problematic fluorescent tubes with a long-life solution. An additional impetus for development was also the phase out of T12 ballast technology, which led many to look for a solution that would allow for the re-use of existing fixtures without costly conversions to different technologies.LED fluorescent replacement tubes allow for replacing linear fluorescent tubes, (commonly referred to as T8/T10/T12), with LED technology. The first products came to market around 2007; however, early generation LED fluorescent replacement tubes not only lacked adequate light output, safety certifications were often non-existent. The lack of quality found in these early replacement solutions unfortunately gave initial buyers a bad impression of LED fluorescent replacement technology.
Today, LED fluorescent replacement tubes are truly able to offer a one-for-one replacement, and have recently reached price levels that offer payback periods well under 12 months. As a result, commercial and residential customers alike have become very interested in the technology, but many are often discouraged by the sheer number of options both in products and installation methods.
How Do I Choose the Right LED Fluorescent Tube Replacement Option For Me?
The first and most important step in choosing which product is right for you is to decide on the installation method you would like to use. The installation method will largely vary on what type of existing fixture technology you have– either T8 or T12.
To figure out what you currently have installed, it is best to remove a bulb from the fixture and read the markings on the end. This will reveal a lot about your current fluorescent tube and usually indicate if the bulb is T8 or T12.
If no markings are available, the size in diameter of the tube is the easiest way to determine the type you have installed.
Image courtesy of RetrofitCompanies.com
T8 tubes are 1-inch in diameter and T12 tubes are 1 1/2 -inch. If you have a tube that is very small in diameter (5/8 inch) you have a T5,and thus the remainder of this discussion will not be of use in terms of helping retrofit this application.
Now that you know what type of tubes you have, the next key is to understand the type of ballast. In general, T8 use electronic ballasts while T12 use magnetic ballasts. Opening the fixture and examining the ballast will give you the ultimate answer as to what type of ballast you have; but, in general, the older the fixture, the more likely it is to have a magnetic ballast.
With the ballast and tube type considerations out of the way, let’s discuss the various replacement options.
Currently, there are four types of options available in the market:
The oldest but also least expensive and most widely installed option is the ballast bypass or direct wire LED fluorescent replacement tube. Instead of building expensive circuitry inside to enable the function with a ballast, this option instead allows the user to bypass the ballast entirely and run directly off of the line voltage at the installation.
Due to potential safety hazards of interacting with line voltage, (which can be as high as 277V in commercial applications), safety testing organizations such as UL have introduced standards to ensure that this product can be installed safely. The result is that most products in this category have to be installed with the line voltage input into one side of the tube.
Non-Shunted Rapid Start Tombstones like this are needed.
This introduces a unique requirement in that the sockets must be of the T12 or “Non-Shunted Rapid Start” type. If you have a T12 fixture, you are in luck, as you have all the necessary hardware already. T8 fixtures must have the input side sockets changed to T12 sockets of the “Non-Shunted Rapid Start” type, as T8 sockets have a circular conductor that will not allow them to properly separate the line and the neutral sides of the circuit.
An example of the wiring for such an installation can be found here.
In this video created by our customer Jeff T, he will explain how to rewire your fixture to accept LED ballast bypass tube lights.
While the wiring is actually quite simple and can be performed in minutes per fixture, it is usually recommended, or in the cases of commercial properties required that an electrician perform this task.
Despite the more complex installation requirements, ballast bypass tubes have large advantages in that their unit cost is lowest versus all other options–an important consideration in the case of a very large project where every dollar counts. For users with T12 fixtures, they offer a compelling option as well due to the necessary socket hardware already being in place.
T8 Electronic Ballast Compatible LED Fluorescent Replacement Tubes
A relatively new option is the electronic ballast compatible LED fluorescent replacement tubes. As their name might suggest, they are meant to work with electronic ballast installations and therefore will not function with magnetic ballasts nor will they function without ballasts. Industry data suggest that this combination alone accounts for over 1.2 billion tube lights, thus they are perpetually growing in popularity.
Like the universal tube technology described below, installation is as simple as pulling out the old tube and swapping the LED tube in its place. Due to the enormous variety of electronic ballasts on the market, many manufacturers have actually done compatibility testing and have developed a full list of compatible ballasts that their LED tubes will work with.
The downsides to this option are once again a higher per unit upfront cost, alongside the continued worry that if the ballast fails the LED tube will not illuminate. Individuals and organizations have to weigh these potential pitfalls against the ease of installation and lack of downtime.
Hybrid (T8 Electronic Ballast Compatible / T8 or T12 Ballast Bypass LED) Fluorescent Replacement Tubes
Some manufacturers have recognized the opportunity to provide LED tube lights that work with Electronic Ballasts (T8) or have the ability to bypass ballasts when the ballast no longer works. This has given rise to a new category, the hybrid tube light. Hybrid tubes work with T8 electronic ballasts but can also be wired directly like a ballast bypass tube light should the ballast fail or if a facility has a mixed environment with T8 and T12 that require both wiring types. This is an advantage for mixed type facilities because the same tube light can be used with a quicker implementation time. Hybrid tubes also allow for the tube light to quickly bypass the ballast if the ballast fails due to their dual operating nature. The primary downside to hybrid tubes are their higher cost and in some cases lower efficiency versus ballast bypass options.
Universal (T8 Electronic or T12 Magnetic) Ballast Compatible LED Fluorescent Replacement Tubes
The newest, most costly but also easiest to install, these LED tubes will literally work with any type of existing technology– be it T8 (Electronic Ballast) or T12 (Magnetic Ballast). The install is as simple as taking out the old fluorescent tube and installing the LED tube. These are a great choice for a homeowner or smaller facilities where the primary goal is total power reduction and no downtime for installation.
The major downside of these options is the up front per unit costs, which can be among the highest. Additionally, since the ballast is still in place it is still a maintenance concern. This is especially critical in T12 magnetic applications where new ballasts can no longer be procured.
We Know LED Fluorescent Replacement Tubes.
We hope this article has served to demystify the basics of choosing an appropriate LED fluorescent tube replacement solution. You can count on EarthLED.com to always carry the best selection of all options available on the market from leading and reliable manufacturers at the best price. Feel free to contact us with any questions you may have when it comes to your next LED fluorescent tube replacement project.
How To Choose Fluorescent Grow Lights For Your Farm
Fluorescent grow lights can be an inexpensive lighting option for a small farm operation, but not every fluorescent light is the same. If you’re not using the right kind, you won’t have enough light to grow.
When should you use fluorescent grow lights?
Most large-scale and commercial operations use LED lights because they last longer and emit more light. Fluorescent bulbs are also more fragile, meaning a farmer can incur additional labor costs to maintain them, and that may not be worth the time or money.
However, the small-scale or hobby farmer may find fluorescent lights to be an economical choice, especially for low-light plants or plants at a low-light stage of development.
As you scale up in size, make sure fluorescents still make sense cost-wise.
“If you’re doing a commercial operation, I’d look at the economics really, really closely before I committed to fluorescent,” says Dr. Nate Storey.
To make the best economic decision about lighting for your farm, compare both the capital and operational expenses of your lighting options over time. (For example, this is how HID and LED compare.) Don’t forget to factor in replacement and heat-removal costs! Another option to consider is LED light bars.
Choose a high-output fluorescent
All fluorescent lights work in a similar fashion:
- An electric current heats up gas inside the tube, which emits ultraviolet light.
- Meanwhile, a phosphorus coating inside the tube turns that ultraviolet light to visible light.
- A ballast on the back converts the incoming electrical current into a usable form.
You’ll see several numbers on a fluorescent light that give you information about how it works, and help you avoid lights that are too dim.
Tubular lights have a “T” rating that tells you the diameter of the tube. T12 lights have that designation because they have a diameter of 12/8 of an inch or 1.5 inches. These tubes were commonly used in indoor lighting applications, but they’re just not very bright, even with a coating to make them full-spectrum.
T5 lights are narrower than T12s, with a diameter of 5/8 of an inch. Look for a T5 bulb with an additional “HO” rating, which stands for “high output.” That means the ballast has been adjusted to make them even brighter—and for growing purposes, more efficient.
“This is the preferred light that we use. This is a very high output light. If you put a T5 next to a T12 and turn them on, you will absolutely see the difference,” Dr. Nate Storey says.
When buying a full-spectrum grow light, you also need to look at the Kelvin rating, which indicates how warm the light is. Fluorescent lights, in general, tend to be bluer but look for a light ranging from 5,600–6,400 Kelvin, which will be indicated on the bulb. On the lower end of that spectrum, the bluer light will give you stockier growth, while the higher rating is great for any kind of vegetation.
Fluorescent lights will also come with a wattage rating to tell you how much electricity the bulb uses, usually 54 watts.
So when should you use a T12 bulb?
Don’t, unless you find one dirt cheap and you use it only for very small seedlings.
Instead, full-spectrum high-output T5 lights are best even for seedlings. They’ll drive growth from the seedling stage through root establishment and until plants are ready for transplanting, at which point you may want to put them under more light. You may even be able to retrofit your fluorescent lights with LED bulbs when the time comes.
Some farmers use high-output fluorescent lights even for fully grown vegetative crops. If you’re growing plants that are fruiting or flowering, however, LEDs are better.
How much fluorescent light is enough?
When you’re installing fluorescent lights, you’ll need to measure coverage yourself using a light meter. There are hundreds of manufacturers of fluorescent lights and too many variables between the lights themselves and their installations to know what kind of coverage you’ll get until you line them up. Make sure your coverage is even and your plants are getting sufficient light.
A very general recommendation for light is 250+ PAR for mature crops. This can be measured with a PAR meter.
Learn more about indoor crop lighting
Check out The Modern Farmer’s Guide to Indoor Lighting. This guide will give you information straight from farmers about making the best lighting decisions. You’ll learn the basics of plants and their lighting needs, how to measure light, types of lights, how LEDs work and how to compare types of LEDs.
Light Requirements for Plants
We have a full line of houseplants that all require different conditions. Light, water, moisture … it gets confusing.
Different houseplants make different demands on their environment. Most plants have their requirements expressed by symbols, which you will find on the care tag of most plants. The trick is figuring out what those symbols actually mean.
Most light needs are divided into 3 specific categories: full sun, semi-shade and shade. However, these classifications are not standardized, so variations do exist. In addition, the number of daylight hours also has an effect on the growth of plants. In winter, there is less sunlight and a plant that received more than adequate light during the summer months may be light deprived in the winter. Be flexible. The number of daylight hours also influences the flowering period and the growth of the plant.
There are two distinctions that can be made regarding the growth and flowering habits of houseplants. Some plants will only bloom whiten there are only a few hours of daylight while others bloom only when the day is long. Short-day plants make flower buds when there is less than 12 daylight hours. Long-day plants flower when there are more than 12 daylight hours.
Growers make use of these characteristics by keep plants artificially dark (the poinsettias are brought on early for the Christmas trade) or growing in artificial light in the winter for earlier blooms.
In general, the three light requirements are:
Full Sun – the plant tolerates unshaded sunlight for an unlimited number of hours each day. It can be placed in or near a south facing window.
Semi-shade – this plant needs a lot of sunlight, but it has to be protected from the strongest rays of the sun. In a south-facing window, blinds should be shading it form direct light. An east facing window, where the sun disappears after about 10 AM, is a good choice as is a west facing window where the plant will receive afternoon sun. This classification is also often called “bright, indirect light”.
Shade – this plant should not be exposed to any direct sunlight, particularly in the summer. A northern exposure is best. This is tricky as you do need some sun, or the plant will not grow.
How Much Light Do Plants Need?
By Steven A. Frowine, The National Gardening Association
Every plant needs light to grow and flourish, but the right amount of sunlight varies. When choosing plants for your garden, look at the plant label to check its light requirements. No matter what light conditions your garden has to offer, at least something should be able to grow there.
Defining light, from dense shade to full sun
You’ll often see terms like part shade, light shade or deep shade to describe a plant’s light requirements. But isn’t shade just shade? And how much sun does “part sun” mean? This list clears the confusion:
Deep or dense shade, full shade. Look for this on the north sides of buildings and walls or under trees with low branches and dense leaves. No direct sunlight reaches the ground.
Partial shade. Find this in areas that get direct morning sun (on the east side of buildings) or afternoon sun (on the west side of structures) but none at midday, from about 10:00 to 2:00 p.m.
Light shade, dappled shade. Look for this under trees with high branches or sparse foliage.
Part sun. Same as partial shade — except plants that like part sun also tolerate midday sun.
Full sun. These places receive direct sunlight for at least 6 hours or more each day, including some or all of the midday hours.
The warmth of the sun, even more than actual light, inspires flowers to unfurl. Sunlight from the east (morning light) is considered cooler, and western sun (afternoon light) can be scorching. Many plants prefer a site with some morning sun, even until midday, and late-afternoon shade. Other plants are able to endure even the hottest conditions. A plant’s tolerance, of course, varies by region. You can place the same plant in a sunnier spot in the far North than in the South.
If you have plants growing in a spot that receives a blast of late-afternoon sun, be sure to monitor their water needs closely so they don’t dry out. If you find they’re struggling, you can help them by installing something to cast a shadow, such as an arbor, or by planting a tree or large shrub in just the right spot. Even companion perennials or annuals planted nearby can cast enough shade to bring needed relief.
Signs of too much, too little sun
Take a daily walk through your garden to spot-check the condition of your plants. If they’re unhappy with the amount of light they’re receiving, you’ll soon find out by the way the plant looks.
Here are some signs that a plant is getting too much sun:
Flower petals dry out.
Leaf edges look burnt or dried.
Flower color looks faded or washed out.
The entire plant starts to weaken and droop.
And here are signs that a plant isn’t getting enough light:
Growth is sparse.
Stems are lanky and spindly.
The distance between leaves, where they’re attached to the stems, is especially wide.
You see fewer flower buds and, thus, fewer flowers.
The entire plant leans toward the light sources.
Some of figuring out the proper location for a plant involves trial and error — you’re aware that roses like a full day of sun, but you really want that bush to go in the nook that gets afternoon shade. Give the spot a try. If the plant’s unhappy, you can always move it to a more appropriate spot.
- Temperature: Plants positioned near a source of heat, such as a heating vent, may not be able to handle as much bright light as a similar plant in a cooler spot. If your plant often looks like it’s wilting, even though you give it regular water, the heat source may be part of the issue.
- Humidity: As with temperature, a low level or lack of moisture in the air can cause plants to wilt and stress. If that happens, you can usually leave the plant in its optimum light conditions if you also mist the plant regularly or provide a nearby humidifier.
- Duration of Sunlight: Most plants need a full day’s worth of sunlight. Luckily many plants go dormant during the winter—including most houseplants. However, you may still need to provide some supplemental lamp lighting, especially if you can’t offer a spot with ideal light conditions for your plant.
- Seasonal Changes: It’s not just day length that varies as the seasons change. The angle of the sun is also different. When the days are long and the sun is high in the sky, your western facing window may get full sun for the entire day. When the days shorten, and the low sun only comes in at an angle, even a western facing window will not be enough light for a plant that craves full sun.
Fluorescent Light And Plants: Lighting Options For Indoor Gardening
The right kind of grow lights can make all the difference in how your plants perform. Using fluorescent garden lights to enhance plant growth allows you to grow a host of plants in an interior space. Standard indoor lights do little to influence photosynthesis, while using fluorescent lighting placed closely to the top of the plants can help drive this important plant process.
About Fluorescent Light and Plants
Modern plant lighting has focused on the LED sources of light, but fluorescent lights are still widely available and easy to use. They are an excellent source of light for young seedlings and plant starts. Fluorescent lights don’t last as long as LEDs but are easy to find and install. Whether you use them vs. LEDs depends upon the light requirements indoors that your particular crop or plant needs.
Fluorescent lights were once the “go to” source of plant lamps. They fell out of favor because they don’t last very long, are delicate, bulky, and don’t provide a high
lumen intensity. Therefore, the bulbs are not ideal for fruiting and flowering plants. Modern fluorescents, however, have increased the lumen output, come in compact bulbs and last longer than their predecessors.
In fact, new T5 lighting systems produce less heat than the old bulbs and can be placed closer to the plant without worrying about burning foliage. They are also more energy efficient and the light produced is readily used by the plant.
Determining Lighting Requirements Indoors
A good light meter can help you determine how bright you need to make the light system. Light for growing plants is measured in foot candles. This measurement indicates the amount of light given off a foot (.30 m.) away. Every plant needs a different amount of foot candles.
Medium light plants, such as tropical rainforest specimens, need around 250-1,000 foot candles, while high light plants need over 1,000 foot candles. You can increase the amount of light a plant receives even with a low output bulb by using a reflector. These can be purchased or use aluminum foil to focus light.
Fluorescent Lighting Options for Indoor Gardening
If you are considering using fluorescent lighting, there are a couple of systems to consider.
- The new T5 fluorescent garden lights are tube lights which provide light on the blue spectrum and are cool enough to touch safely and won’t burn young plants. The number 5 refers to the diameter of the tube.
- There are also T8 tubes that are similarly efficient. Both produce plenty of light but are of a lower wattage than older fluorescents and, therefore, more economical to operate. Purchase tube lights with an HO rating, which indicates high output.
- Next are the CFLs or compact fluorescent tubes. These are great for small grow spaces and can be used in an ordinary incandescent light fixture.
No matter which you choose, fluorescent light and plants will increase growth and output in interior situations.
Easy Beginner Grow Cannabis Guide w/ CFL Grow Lights | How to Grow Marijuana
Maintenance Cost: $50/month
Yields to Expect: 1-3 ounces/plant (if you follow the directions in this tutorial)
Time to Harvest: An average CFL cannabis grow takes about 12 weeks from seed to harvest. Some strains (like auto-flowering cannabis strains) can be ready as soon as 8 weeks from seed. With other strains, you may need 14 weeks or more to get to harvest (learn how to get to harvest sooner). Strain choice is very important when it comes to timelines! Learn how to find the right strain.
Recommended For: People who want a super-cheap, super-easy grow style.
Don’t be fooled just because it’s easy. Even though I was a complete beginner when I started, I ended up getting 6.2 ounces of dried buds off my very first cannabis plant from my very first grow, which I grew using this system! (Pics below). That is an unusually lot of cannabis for a CFL grow, and took using a LOT of bulbs, but if you read through this whole tutorial you’ll learn step-by-step how you can do it, too.
It helps to use a high-yielding strain (Northern Lights is great because it’s high-yielding, tends to grows short, and is low odor).
I also train my cannabis plants to take advantage of the great light that CFLs produce within 2-8″ of the bulb.
These results are not typical for your first try unless you’ve put in a lot of extra research and really watch and tend to your plants throughout your grow. Which brings me to my next point.
This method is not for everyone!
That’s because growing weed with CFLs isn’t the highest yielding method. It doesn’t get the most yields for the electricity, it’s not suitable for a large grow, and it’s not going to work if you aren’t willing to watch over your plants closely throughout the grow.
But it’s super cheap, super easy, and if you just need a few ounces of bud every few months, it may be the perfect “low-maintenance” way for you to grow weed!
I think it would be safe to assume that even a beginner can expect to get 1-3 ounces of dried buds per plant if you just follow these instructions. Even if you mess up (and you will), you’ll still get at least that if you can get your plants to harvest.
You will be growing your marijuana plants indoors in a soil-less medium called Coconut Coir (often called coco coir, or even just coir). Coco coir is a natural fiber made from the husk of coconuts that naturally stimulates the roots of plants and is forgiving when growing marijuana.
For feeding (water plus nutrients), you will hand-water them whenever your plants get dry and you will provide them with all the nutrients they need right in their water.
For lights, all you need are some cheap CFLs (Compact Fluorescent Lights) like the ones you get from your local hardware store.
These common bulbs are much more efficient than old-fashioned light bulbs (which can’t be used to grow plants) and CFLs don’t use much electricity or produce as much heat compared to some other grow lights.
For a stealth marijuana grow inside a tiny space, nothing can beat CFLs as marijuana grow lights.
Because CFLs have a short light range (8-12 inch max), this tutorial works best for growing plants that are kept shorter than 3-4 feet. You want to focus on training your plants to grow wide instead of tall.
That means you will choose either…
- A compact grow when you keep your marijuana plants small and harvest often (great choice for beginners who want a quick harvest) OR
- A controlled grow where you allow your plants to get bigger / wider, but you maximize the CFL light range by training your marijuana plants to grow short and bushy. This is a great choice for growers who don’t mind waiting a few more weeks in order to get a bigger harvest.
You can still get at least a couple of ounces off each plant, even when plants are kept short and you will be able to harvest your crop in only 3-4 months.
This system reduces many of the problems associated with an indoor soil grow, and is also much easier than almost any other hydroponic style grow.
It is a great way to learn about how marijuana plants grow and after doing one harvest yourself, I guarantee that you will start getting millions of ideas on how you want to do your next grow.
Pros of Growing Marijuana with CFL Grow Lights and Coco Coir
- Cheap and easy to start
- Cheap and easy to maintain even for a complete beginner
- Forgiving way to learn how to grow weed
- Perfect for growing 1-2 plants
- Get 1-3 ounces/plant (harvest yields depend on the strain, how big you grow your plant ,and the light intensity you provide to the buds during the flowering stage)
- High quality bud since the plant is fed hydroponically
- Suitable method for a very small grow space
- Can be used with any strain of marijuana, whether starting with seeds or clones
- If you ever upgrade down the road, you’ll still be able to use all this equipment for seedlings and vegetating marijuana plants; this setup is easily turned into a dedicated vegetative chamber
Cons of Growing Marijuana with CFL Grow Lights and Coco Coir
- CFL grow lights are not cost effective when growing more than 1-2 flowering marijuana plants at a time, if you’re growing more than a handful of plants, you’ll probably want to invest in a LED Grow Light or LEC grow light to supplement your light intensity. Learn about the various marijuana grow lights you can add if you want to really ramp up your yields (instead of just trying to add more CFLs).
- Hand-watering plants is simple, but can be a pain if you have a lot of plants OR very small pots (which need to be watered more often)
- You have to adjust your CFL bulbs 1-2 times a week, as your plants will be rapidly growing into them
- For best results and to be able to harvest several ounces/plant with this method, you will need invest your time to learn how to keep your marijuana plants short with basic marijuana growth control techniques
This is really a perfect way to grow your first harvest if you “just want to get your feet wet” because it’s low cost and so forgiving it’s hard to mess up. Plus, you will really learn an incredible amount about cannabis growing by using this method.
I used this technique for my first grow, and even though I made a lot of mistakes, my plants produced great buds.
What you will need
- Marijuana Seeds or Clones
- High-quality hydroponic nutrients which are designed for growing marijuana hydroponically. Any quality cannabis nutrients made for hydroponics will work well as long as you also use a Cal-Mag supplement. I personally use the General Hydroponics Flora trio plus Calimagic (a Cal-Mag supplement) for growing in coco coir. This is a tried and tested nutrient system for any type of hydroponic growing. You can actually follow the nutrient schedule on the bottle because it’s formulated for plants like cannabis, just start at half-strength. Here is the exact nutrient schedule I’m using right now from them (pdf). I also recommend Fox Farms Hydroponic Liquid Nutrient trio since that’s what I exclusively used with good results on my first grow. Learn more about different cannabis nutrients.
- Pots to plant your marijuana in. Learn all about cannabis growing containers. Since you want to keep plants relatively small when growing cannabis with CFLs, you’ll generally want smaller containers (1-3 gallons each) for your plants. If you do get bigger containers (5+ gallons), you should still start your plants in smaller containers until they outgrow the current one and need a larger pot.
- Coco Coir Potting Mix. You can buy done-for-you Coco Coir potting mixes online or at hydroponic garden stores, which can be used immediately just like regular soil. But the cheapest and most widely available type of coco coir for growing comes in brick form. Here’s a tutorial showing you how to hydrate coco coir bricks into a nice fluffy soilless coco mix that your plants will love.
- CFLs (Compact Florescent Lights). You want at least two 40W ‘daylight’ CFLs to start (note: a 40W CFL is the same as a 150W incandescent equivalent, don’t let them trick you). You’ll be adding more CFLs as your plant grows and needs more light. You should plan on getting around three more 42W ‘soft white’ CFLs for the flowering stage. CFLs are found everywhere, in stores and online. For growing cannabis, I like bulbs close to the 40W range because they are a small, manageable size but still produce a lot of light. By the time your cannabis is flowering (making buds), basically the more light the better. When it comes to CFLs, you pretty much can’t give your plant too much light. It’s optimal to use ‘daylight’ (6500k) colored bulbs for the vegetative stage and ‘soft white’ (2700k) colored bulbs for flowering, because this more closely matches what the sun is doing in summer and fall, but you can use any color spectrum CFL during any stage of life and your cannabis will grow well. The total amount of CFL wattage you give your plants is much more important than the color spectrum of the bulb. Learn more about how many CFLs to use for the yields you want.
- Enough light sockets for all your lightbulbs – they’re about $5 apiece at my hardware store, and a few bucks more online. Sometimes they also come with some sort of clip you can use to clip your lights anywhere. A 4-way splitter is a great way to get more sockets in a small amount of space for less money.
- A timer to make your lights go on and off when you want. You can get a cheap mechanical one or spend more for a nice digital one, and they’re found in hardware stores or online. The timer I use cost less than $10 and has served me well for years. You don’t necessarily need a timer to start growing, but you will need one by the time you start flowering your plant (about a month in).
- pH Control Kit: This contains pH Up and pH Down (to adjust pH of your water) and a simple strip test. Another option for testing pH is a fancy (and more expensive) digital pH tester though my plants did just fine with the strip test that comes in the much cheaper pH Control Kit. All hydroponic stores and some gardening stores with sell pH Control Kids. You will want to adjust your water so it’s around 5.5-6.0 pH when you water your plants. How do I check and adjust the pH of my water?
- (Optional) Grow Tent: If you don’t have a good growing space, you can easily buy one that’s perfect for growing cannabis! A 2’x2’x4′ Grow Tent is great for small spaces. If you have more space, a larger model such as a 2’x4’x5′ Grow Tent will give you a lot more flexibility as far as accessing your plants and being able to arrange your lights. You can also use a 2x4x5 with bigger grow lights such as a 250W HPS or even a 400W HPS, so you’ll have the ability to upgrade your grow down the road. I always recommend getting the biggest grow tent size you can fit, as you’ll always wish you had more room! Learn more about using grow tents for growing weed.
Estimated Total Cost for Growing One Plant
- Seeds or Clones – Free – $10+/plant (learn how to get marijuana seeds in the US)
- Nutrients – General Hydroponics Flora trio plus Calimagic (a Cal-Mag supplement) – $55
- Coco Coir – $20 for a done-for-you bag of coco mix, or about the same for a coco coir brick + perlite. (learn how to rehydrate a coco brick)
- Container – 2 or 3-gallon pot – $1 – $8
- Two 40W ‘daylight’ CFLs for the vegetative stage – $20
- Three 42W ‘soft white’ CFLs for the flowering stage – $35
- Light sockets – you need a light socket for each of your CFLs. They usually cost less than $10 each, and you can get cheap 4-way splitters to be able to use less sockets/cords for even cheaper. For five sockets (to account for your five CFLs), it will run less than $50.
- Light Timer – An average timer costs about $10 though some digital ones can cost $30 or more
- pH Kit – A complete pH kit costs $10 – $30
Total Startup Cost for One Plant: $201 – $258
Each additional plant needs an additional container, coco and 5 more CFLs and light sockets, for an additional setup cost of about $100/plant.
Important! If you plan to grow more than 2-3 plants, I highly recommend upgrading to a small LEC, LED or HPS grow light as you will get a better “bang for your buck” than with CFLs as far as yields for electricity. An LEC, LED or HPS will yield 2-4 times as much bud as you would get with CFLs for the same amount of electricity. CFLs are much better suited for just one or two plants, or for growers who want to “dip a toe” in growing without investing too much.
So, you can see that it doesn’t cost that much to get started growing cannabis with CFLs! After you get going you can expect to spend about $30/month in electricity, supplies, etc. considering an electricity price of $0.12/kWh (average cost of electricity in the US). So, if you harvest in 3.5 months, which is the average time, you’ll have spent about a total of $300 – $360 for your entire first grow, including setup, electricity, nutrients and maintenance. After that you can expect to pay about $100/grow since you won’t have to invest in most of the setup costs again.
Spend about $300 and Harvest 2+ Ounces From One Plant!
2 ounces (~60 grams) per plant of bud retail value: You may get even more but a reasonable estimate for someone who follows the directions is to harvest at least two ounces of dried bud from each plant. At $10-$20/gram (prices around here), two ounces of cannabis is equal to $566 – $1133 which is worth much more than the money you need to put in to get started. And the amount you spend will go down each grow, while your yields will likely go up. Plus, you don’t have to go anywhere to get your buds! I got a total 6.2 ounces of dried buds off my first cannabis plant I grew using this system (pictured below in flowering section) but to get those kinds of results you need to train your plant and invest in more CFLs as the plant get bigger to make sure there aren’t any shadowy areas.
After your first grow, you will only need to get more plants, more coco coir, and more nutrients which will significantly bring down the start-up costs for subsequent grows.
Remember, you can start out with fewer lights and light sockets (start with 2 per plant), and will only need to get more as your plants get bigger. The great thing about all of the items needed for this technique is they can all be used in future grows, even if you decide not to continue with this method. For example, even if you end up getting more powerful grow lights eventually, you will always be able to use the CFLs for starting out new plants, or for adding additional side lighting.
A Note about Using CFL Lights
You need about 80w of CFLs per plant to start; I prefer to start with two 40W per plant
This is what I use for each plant:
- Two 40W ‘daylight’ CFLs to start
- When the plant starts budding, I recommend adding at least an additional three 42W ‘soft white’ CFLs for the flowering stage. You can add even more if you have the space. More light = more bud when it comes to CFLs in the flowering stage.
These lights are easily found at the store or online. You can get lower or higher wattage bulbs, but I like bulbs close to the 40w range because they produce a lot of light, but are still a small, manageable size.
You’ll likely need to add CFLs a little as a time while your plant grows, but by the time the plants are flowering, you definitely want more light than your original two bulbs to get your plants to produce lots of bud. Light is what gives your plant energy, and the more energy it gets, the bigger buds it will grow.
More Light = More Bud
(up to a point)
It’s optimal to use ‘daylight’ (6500k) colored bulbs for the vegetative stage and ‘soft white’ (2500k) colored bulbs for flowering, but you can use any color CFL during either stage and your plant will grow well. The color spectrum of the bulb is not nearly as important as the total wattage.
Instead of just plain sockets, you may decide to get some heavy duty clamp light sockets which you can use to power your light bulbs. These light sockets have a reflector built in and are able to clamp to most anything.
When looking for clamp light sockets, avoid anything that’s made of plastic (it’s cheap and will break) and try to find something with at least a 9-foot-long cord. You might be surprised at how annoying it is to try to find a way to make a 6-foot cord work.
To maximize the light your plants are getting, you can use a 2-way or 4-way splitter plus a light socket extender to fit more bulbs per each clamp light socket (without the extender, they might not fit inside the reflector).
Setting up more than one bulb per socket can often be cheaper than buying an individual light socket for each light, especially if you buy online. It also is really convenient for arranging around your plant.
How to get started
Note: Perlite can often be found in garden stores or the garden section of places like Home Depot and Lowes. I normally advise against all things Miracle-Gro, but their 8-quart bag of perlite is okay for this tutorial if you can’t find anything else. But remember, never use Miracle-Gro time release soil or their standard nutrient formula! But their perlite is okay.
Read the full tutorial on how I make my coco coir mix
Water your pot with coco coir thoroughly until water drains out the bottom before adding your seeds or clones.
Set up your lights so that they can start around the height of your pots and eventually be raised to the final height of your plant (2-3 feet depending on your marijuana strain and how long you let your plants stay in the vegetative stage).
Once you have everything set up as described, simply add your marijuana seeds or clones and set up your lights so that they’re about 4 inches away to start.
You will want to start feeding your plants with nutrients at quarter strength for the first week, then work your way up to full strength slowly.
I recommend following the instructions exactly as provided by the nutrients.
For example, if you are using Fox Farms Hydroponic Liquid Nutrient trio, just follow the feeding chart that comes with the bottles and water your plant with nutrients every other watering.
When not using nutrients, make sure you still pH your plain water before your feed your marijuana!
This is important! Water your marijuana plants until you get at least 20% extra runoff water out the bottom.
Then don’t water your marijuana plants again until the top of the coco coir starts feeling dry.
This will start out with you watering the plants every couple of days, and may end up with you watering them once a day towards the end of the marijuana flowering cycle.
This bears repeating, you want to ensure that you have about 20-30% extra run-off water come out the bottom of the container every time you water your plants.
The reason for this is that coco coir tends to form natural salts if it the fertilizers just sit in there and never get washed out. Making sure you keep adding water until you get run-off is also a great way to make sure that your plants are draining properly.
As I said before, make sure to feed your marijuana plant with plain, pH’ed water every other watering.
This will greatly help reduce the amount of salt buildup and prevent nutrition problems from occurring. If your marijuana shows signs of drooping, chances are you are over or under-watering.
In order to prevent over or under-watering, make sure you water thoroughly every time, and wait to water again until the top inch of coco coir feels dry.
After your plants have grown accustomed to their new environment (after a couple of days for transplanted clones, or when your seeds grow their second set of leaves) then you will want to move your CFLs so that they are about an inch away from the plant.
CFLs lose a lot of light the further away they are and their light is almost useless once the plant is 6-8 inches away.
Your biggest task when growing your marijuana will be adjusting the lights.
The CFL bulbs should always be as close as possible to the plants, yet they need to be far enough away that your marijuana doesn’t grow into the lights and burn its leaves.
If you check on your plants constantly, you can keep the lights closer. If you’re going to be away for a while, you should move the bulbs away to give your marijuana some growing room.
Personally, for me, adjusting the lights was one of the most fun parts of growing marijuana using this method because it gave me something to do while I was hanging out in my grow room.
As a beginner, I always wanted to keep checking in on my marijuana plants all the time, and adjusting the lights gave me something I could do to satisfy that urge. You may also want to rotate your plants every day in order to provide the evenest amount of light from all sides.
Your marijuana can’t get really get too much light from CFLs and the only thing you need to worry about with the CFLs is burning your plants if they get too close.
Basically, if you put your hand where your plants are closest to the light, and the light feels too hot to be comfortable, then the light is too close. If your hand just feels warm, but not hot, then your plants are at the perfect distance. I generally kept my CFL bulbs 2-4″ from the leaves during the whole grow.
If you notice that your plant is growing with a lot of space between nodes or otherwise seems like it’s ‘stretching’ upwards, that means that it probably needs more light. Try adding an extra CFL or two or move them closer. If you notice your plant is having any other issues or something doesn’t seem right, check out the Plant Problems and Symptoms Guide.
When your cannabis plants are about half their final desired height, you will change them over to the flowering stage so they start growing buds.
By half the final desired height, I mean, if you wanted your plant to achieve a final height of 2 feet, then you would switch your marijuana to flowering when they’re about 1 foot tall, or half of 2 feet.
If you wanted your marijuana to grow to be 5 feet tall, then switch them to flowering when they’re at a height of 2.5 feet.
The reason for this is that marijuana will generally double in height after being switched over to the flowering stage.
To initiate the flowering stage, you will switch your light schedule so that your lights are on for 12 hours a day, and off for 12 hours a day.
During the ‘off’ period, your marijuana should be in total darkness.
This light schedule will trick your marijuana into thinking that the days are getting shorter and fall is coming.
The 12-12 light schedule will cause your plants to begin the flowering stage and start focusing on making buds instead of just growing.
If you don’t change your schedule to 12-12, chances are your marijuana will just keep growing forever and never make buds.
After switching to 12-12, you should start noticing your plant making its first sex organs after a week or two. Females will grow white hairs and males will start growing grape-like balls.
In order to maximize the amount of bud you get, you will want to make sure you remove any males so they don’t impregnate you females. If they stay together than your females will get pollinated by the males and will end up making lots of seeds instead of buds.
Unless you have a reason to keep males (for example breeding), you probably want to just kill any male plants because they won’t make any usable bud anyway.
When growing with CFLs, it becomes harder and harder to fully illuminate the plants as they get bigger and grow more branches. You will maximize the total amount of buds you get by keeping the plant smaller (and therefore easy to bathe in light), and then harvesting more often since your plants will be ready to harvest much sooner.
As the plants get taller and start blooming, you may need to get a couple more CFLs to light them from the sides. Basically if you see any dark or shadowy areas that are more than 6 inches from a CFL, then you should get another CFL to plug in that ‘hole.’
Towards the end of the flowering cycle, as your marijuana approaches harvest time, you may notice that some of the oldest leaves start turning yellow and falling off. This is totally normal and is a sign that your plant is taking nitrogen out of the leaves and putting them into the buds/flowers.
You will want to stop feeding your marijuana any nutrients for the last two weeks before harvest to ensure the best tasting bud. Simply feed them plenty of water without nutrients for these last two weeks, but make sure you’re still adjusting the pH so they absorb any leftover nutrients in the coco coir.
I usually stop feeding my cannabis nutrients and start feeding them water when about 75% of all the pistils (hairs) have turned dark and started curling in towards the buds.
Please view the Harvest tutorial for more information about when and how to harvest your plant. This guide will tell you exactly what to look for as far as determining if your cannabis is ready for harvest.
Basically, you’re waiting for your cannabis flowers (which are initially covered in straight white hairs) to darken and curl in. When the buds are ready to harvest, nearly all the white hairs/pistils will have turned orange and curly.
When using this method, I’ve found my cannabis to be really resistant to issues or problems, especially considering this method was the one I used for my very first harvest and I had no idea what I was doing when I started.
Over the course of my first grow I made several mistakes, including dropping a light on one of my plants and accidentally burning some of the leaves on the lights. Every time something happened to a plant, it seemed to take it in stride and just keep growing.
Despite all my mistakes, I still got 6.2 ounces of dried buds off my first plant grown with this grow method!
I really like this technique for a beginning cannabis grower because it’s a really good way to get a feel for how plants grow and how the cannabis plant grows in particular.
It can be hard to decide what you want to do for you first grow, and this is a really cheap yet effective way to get started with growing and get good results.
After having one successful grow under your belt, I guarantee that the whole process will start making more sense.
Even if you end up eventually moving on to other types of growing systems, you will be able to use many of the materials from this system with your future grow.
If you end up using this technique or have any other thoughts or comments I’d love to hear from you!
How to Grow Weed: Basics
Coco Coir as a Cannabis Grow Medium: Full Guide
Growing Weed with CFLs Starter Shopping List
Grow 4-7+ oz in Coco Coir with a 250W HPS – Step-By-Step Beginner Tutorial
A Compact Fluorescent Light (CFL) bulb
The short answer is: any type of fluorescent light will help any type of plant grow, whether it is cannabis or lettuce or orchids.
But it’s not quite so simple.
While you can use any type of tube or bulb and see results, you want to provide the kind of light your plants want most.
That’s how you get the best results.
So what type of light do your plants need?
That depends on a few things.
- Are they plants that flower (like marijuana) or ones that don’t?
- If they flower, they need different type of light depending on their current stage of growth, so you’ll need to take that into account
- Are they already getting some natural light or will they be growing under artificial light only?
Fluorescent Growing Lights: CFL or T5 Tubes?
An Agrobrite T5 fluorescent fixture
Before we get into the specifics on the types of bulbs or tubes, let’s first decide whether we want to go with fluorescent tube lighting or with compact fluorescent bulbs.
The answer is simple.
If you’ve got a very small garden, CFL bulbs (pictured at the beginning of the article) make the most sense.
If your garden is large enough to warrant a larger T5 tube fixture, go with that. And perhaps supplement the light with a few CFLs, especially for plants with high light requirements, like weed.
As for which bulbs to get, it doesn’t matter with CFL bulbs. You can just get any standard bulb from your local Home Depot or Walmart or order online (if you’re unsure about the correct color temperature, I cover that below).
Amazon has a bunch of CFL bulbs, too.
There is no need to get a specialized (and overpriced) grow bulb. They’re basically the same thing. It’s just a way to get more of your money.
For T5 fixtures, I recommend the Agrobrite line from Hydrofarm (pictured above). We reviewed them here, but the quick summary is that they cost about the same as most no-name fixtures from China, but work far, far better.
You can use regular fluorescent bulbs from any local store, but for larger fixtures like this, it make more sense to buy from a company specializing in horticultural lighting. And Hydrofarm is the biggest name there is.
Now, let’s take the first question from above and tackle plants that flower and those that don’t separately.
The second and third questions will be answered naturally as we go along.
What Fluorescent Bulbs for Growing Flowering Plants (Marijuana, tomatoes, etc)?
A CFL with a warm white spectrum for flowering.
Flowering plants, like cannabis, need more and different light than non-flowering plants. But only during the latter stages of growth.
In the beginning, flowering plants need the same light as non-flowering plants. When they are seedlings and when they are growing (vegging), they need light that contains more blue than at other times. This is also often referred to as ‘cold light’. It is the kind of light our sun gives off naturally during daylight hours.
When the plants have grown enough to begin fruiting or flowering, they need more light than before and they prefer a warmer light, i.e. light that contains more red.
So how can we give them the light they need with fluorescent bulbs?
By using bulbs with varying color temperatures.
During the seeding and vegging stages, we want to use bulbs labeled ‘cool white’ or ‘daylight’. They will have a color temperature (usually indicated on the package) in the range of 6000K to 6500K.
During flowering, ‘warm white’ bulbs are ideal, with a color temperature of 2700K to 3500K.
It might seem like a hassle to change bulbs when it is time to go from vegging to flowering, but it’s really only a big deal if you have a very large garden with a lot of lights.
And if that is the case, you should not be using fluorescent lighting anyway, as the disadvantages outweigh the advantages once a grow gets too large.
However, if you just don’t want to bother with having to change the bulbs, you can get lights with a color temperature in the middle, somewhere around 5000K.
These bulbs will work fine for all stages of growth. In reality, any bulb will work for any stage, but using bulbs that provide the right kind of light yields much better results.
In most cases, you will want to supplement the light you use during vegging with some additional bulbs. Personally, I just hang a few CFL bulbs (warm light) here and there to add some more output and really stimulate flower and bud production. If you are unsure how many CFLs you need, this article will help.
What Kind of Fluorescent Bulbs for Plants that Don’t Flower?
A CFL with a cool white spectrum that is ideal for vegging.
If you are growing plants that don’t flower, like cacti, herbs, lettuce, etc. then you do not need to worry about providing warmer light during flowering.
You just need to get some ‘cool white’ or ‘daylight’ bulbs and use them all the time. No need to switch lights. This article reviews the best T5 bulbs for vegging.
Best Fluorescent Grow Lights
Let’s quickly summarize which fluorescent lamps are best, whether you are interested in getting CFLs or T5 lights.
As mentioned above, when it comes to compact fluorescent lamps, I would not worry about getting a dedicated grow bulb. They cost a lot more, but are basically the same as a regular CFL bulb.
As for which brands are best, follow the links provided above to see my recommended bulbs for each color temperature. I like those lamps, because they offer the best value for money.
Amazon will also show you other options, so you can easily see some alternatives and do a quick comparison for yourself, if you don’t like my recommendations.
When it comes to T5 lights, I always recommend the AgroBrite fixtures from Hydrofarm. Check out my AgroBrite review to see why I prefer these lights.
If they don’t have a fixture in the size you need, or if you only need bulbs, this post reviews and compares the top T5 tubes on the market.
Update: while I still love fluorescent light for growing cannabis and other plants, these days I tend to recommend T5 LED lights instead. They are basically exactly the same as a T5 fluorescent light, but they run cooler and use less power. They also last much longer.
They do cost more, but end up paying for themselves within a year, since they cost less to run and you don’t have to replace them for many years.