How to stop plants from stretching?

Preventing and Fixing Long, Stretchy Stems

In This Guide You Will Learn:
How to Prevent And Fix Long Stretchy Stems

  • Why do seedlings stretch?
  • Why stem stretching is an issue
  • Ways to reduce the risk of stretching
  • Fixing Stretched Plants

Elongated, stretchy stems are the bane of any new marijuana grower. They don’t provide a stable base for a seedling, which can end up affecting the plant throughout its lifecycle. But, getting rid of the stretchy stem is really a matter of replanting the seedling, so it doesn’t continue to grow disproportionately.

Why do seedlings stretch?

There are several reasons why a marijuana plant may stretch. Sometimes there is nothing you can do to prevent a plant from creating tall stems regardless of your efforts to stop it.

Why do seedlings stretch?

Many factors may cause a marijuana seedling to stretch. Some are biological and others aren’t, however in all cases, the plant grows differently as a result. Here are just a few reasons why a seedling might stretch:

  • Lack of nutrients in the soil
  • Unstable temperatures
  • Improper lighting schedule

There’s also the plant’s genetics. If a marijuana plant’s parents were originally grown indoors or if they promoted the growth of crowding plants, there is a chance that natural selection kept this trait in the seed’s genotype. But if those seeds were made by a ‘’Willy-nilly’’ crossing from hybrid plants, their offspring will be so variable that it will be hard to know what to expect. Keep in mind, some plants just naturally grow taller than others. One example of a strain that grows tall both indoors and outdoors is the tropical, landrace pure Sativa.

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Sun-hungry behavior

Marijuana plants love light, but some plants may love it a bit too much. SARP is term used among growers that is short for “shade avoidance response phenotype.’’ This is when a plant stretches to reach light that is being stolen by a neighboring plant.

Did you know that plants are perfectly aware of their surroundings?

A marijuana plant can sense when a neighboring plant is close due to less red in the light that is reflected off. This also means they are less likely to stretch when red spectrum HPS lights are used because they have enough. Of course, temperature and the timing of the growth cycle play a role in the phenomena as well; so, the overall environment is still critical. It can decide if SARP behavior starts to show.

Factors that make your plant more likely to stretch include:

  • Space between plants
  • High temperatures
  • Not enough light
  • Distance to the light

It’s important to understand that SARP isn’t solely about access to light. It is a mixture of outside factors that interact with the light quality. The amount of light would not be as much of an issue if the plant did not feel threatened by the presence of another plant. However, when the plant is not exposed to light for a long enough time, it becomes more sensitive to the specific red spectrums needed for growth. When the photoperiod (length of light exposure) is long enough, the spectrum is less relevant.

Stretching, that is not due to shade avoidance, on the other hand, can occur with plants that do not get enough light in terms of intensity. In an indoor setup, it could be that the lamps are too far from the plant. It is literally trying to reach the light. Even though crowding is not the issue, this type of stretching is still a problem because these plants may have a higher risk of premature flowering.

Why stem stretching is an issue

Marijuana plants can develop stretched stems when grown both indoors and outdoors. They may be easy to miss, since a stretched plant may still be large, however, the yield will be much less. Stretched plants are more expensive to grow since those long stems need extra energy – energy that could have gone to growing bigger buds.

Indoors, these decreased yields are likely related to the challenges of creating proper lighting in an indoor grow.

Stretching can also create fragile stems, which means the plant is at risk of falling over. It is also definitely an issue where ceiling height is a concern.

Stretching can be a big problem, but there are ways to prevent it from happening.

Ways to reduce the risk of stretching

Air Circulation

Having good air circulation will allow the stems and leaves to get thicker and stronger while at the same time reducing how high it grows.

Strong air circulation can create stem and leaf movement that strengthens and widens the stem while also slowing its vertical growth. Winds will bend the stem, creating small rips in the plant’s tissue. You can also just brush the leaves to simulate the effects of air circulation.

Ways to reduce risk


The type of light you use also plays a role in how tall your stems will grow. Orange and red lights provoke taller, thin stems, but thick, short stems blue light is best. Using metal halide lamps while the plant is in the vegetative stage will produce short stems.

Another way to control the height of your plant is by using infrared light. You use these when the lights are off. A black cloth covers the heat lamp reflector, which makes it so the infrared rays create the right results. At the same time, it catches red light to prevent contradicting what you are trying to accomplish. It is best only to use this light during the flowering stage.

The distance of the lights from your plants can also lead to stretching. To avoid stretchy stems make sure your marijuana seedlings get enough light.

In an indoor setup, place your plants under a CFL bulb (3 watts per seedling). The distance between plant and CFL bulb should be around 2 inches. If using HPS bulbs, the distance should be around 40 inches for seedlings (20 inches for vegging plants) but make sure temperatures don’t exceed 77 ºF.

Outdoors, the distance may not be as relevant, but the amount of sunlight will be. Make sure you are growing according to your region’s growing calendar. In some cases, shorter days may cause plants to stretch – regardless of the amount of sun they are getting during the day. Even in the most tropical areas, outdoor plants may need additional nighttime lighting to prevent stretching during some seasons.

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Heat and Stem Growth

The temperature influences how your stems grow. The higher the temperature, the longer the stems will grow. Your plant’s stems will widen, and the growth will lessen at about 60*F. When you have it around 80*F, the stems and buds will begin stretching.

If your buds get too close to the light, this causes it to become tall and thin. Don’t make the mistake of thinking this is light burn because this is not the case. In fact, the heat from the lamps can make it unbearable for buds. Air-cooled lamps are great for keeping much of the heat from coming into the room.

Not having the proper amount of light will lead to stem stretching. As a result, the seedlings will grow tall, thin stems because it is trying to access more light. As a solution to this problem, give it a more intense light schedule, or you can place them nearer to the light. Once you have done this, the stems will grow thicker and do much better on their own.

Lastly, try pruning as a way to reduce stem stretching. By cutting off the top of the stem, it makes the rest of the branch grow.

Spacing In-between Plants

Growing your plants in bulk leads stretching. As your plant grows, the leaves may easily start coinciding with the plant next to it. Over time, this causes the bottom of the plant to be discolored, and the sub-canopy will get darker.

Reduce Stress

Stem stretching is the result of many factors, which include high/low temperatures, transplant shock, light spectrums, and humidity. Keep your plant happy by making sure the environment is the best for your plant.

Fixing Stretched Plants

If your plants have already started to stretch there are some ways to fix the problem, if you notice it early enough. If it is during the vegetative state or the first two weeks of the flowering stage, you can use blue lights to reduce it. This simple step could save a bunch of trouble later on.

Keep in mind, stretching isn’t always a bad thing. Some growers like a bit of stretch and feel that is good for avoiding bud rot in certain strains. But in most cases, stem stretching is not desirable.

Stretchy as an issue

If you do notice that your plant is stretching, refrain from giving it too much nitrogen. Instead, use a fertilizer ratio of (2-2-2) at the beginning of the flowering stage to keep the nitrogen levels average. Remember to keep it gradual. Making an instant shift to the normal flowering ration right after the vegetative stage causes yellowing.

Also, use oscillating fans if you’re growing indoors. A little bit of movement helps make your stems healthier.

If your plants have already experienced large amounts of stretching, here are two ways to nurse them back to life.

Bury the plant

Giving the plant a stronger base can help it stand up straight while the stems grow back stronger. You can create this base by basically re-potting the plant.

First, you’ll want to make sure the soil is dry. If it’s wet, the roots will have a tendency to cling, and you don’t want them to be damaged in any way. Then, very carefully remove the marijuana seedling from its current container. Clean off the roots so that there is no more soil attached.

You may want to use a deeper container or just dump the soil out from the seedling’s current container. Leave a little bit of soil in the bottom of whatever container you decide to use so that the roots won’t try to grow through the drain holes. Place the seedling down in the container in such a way that you can bury the stem. It is ideal to bury the stem almost completely so that only the Cotyledon leaves are showing. After that, provide the marijuana plant with just a touch of water to get it going again.

At this point, your stem will be buried, and it will eventually start to grow roots of its own. This is something that can apply to little seedlings and even incredibly long, emaciated stems. Again, as long as you’re extremely gentle with the plant, you should cause no harm, and the plant will not be stressed.


You can also reinforce your plant by using stakes. Various growers have devised methods of staking their plants so that the stems can recover.

You could use some sort of fabric, such as fabric or yarn to create a lattice around weak, stretched stems. This works especially well in a greenhouse where you can simply tie the plants so that they remain standing.

TIP: Looking to buy seeds? Visit the ILGM marijuana seed shop

Others use traditional stakes made out of plastic or bamboo and tie or tape weak plants to them for support.

If you decide to use stakes or otherwise tie your plant, be careful not to damage the stem in any way. The idea is to provide support, not stress, otherwise, the stretching will not stop. If you use stakes, it may be a good idea to invest in specialty gels that strengthen the stem during the process.

The founder of I Love Growing Marijuana, Robert Bergman, is a marijuana growing expert that enjoys sharing his knowledge with the world. He combines years of experience, ranging from small-scale grows to massive operations, with a passion for growing. His articles include tutorials on growing…

Marijuana plants that have stretching stems are problematic for grow rooms and outdoor gardens in which height is a major concern.

Marijuana plants stretch for a variety of reasons. Genetics is the most obvious reason. Some plants are programmed to produce long stems no matter how much you try to prevent it. Sativa strains that grow tall outside will do the same when indoors. Excluding genetic factors, there are some things that gardeners can do to decrease stem length between leaves.

Strong air circulation can create stem and leaf movement that strengthens and widens the stem while also slowing its vertical growth. Winds will bend the stem, creating infinitesimal tears in the plant’s tissue. The plant will then quickly mend these small tears by growing new tissue. Simply brushing or bending the leaves and stem can mimic the benefits provided by air circulation and, thus, widen and strengthen the stem. Download my free marijuana grow bible and learn more about growing marijuana.

The light spectrum can also serve a purpose when it comes to controlling height. Blue light will promote shorter, sturdier stems while red and orange light will stimulate longer, skinnier stems. If exposed to metal halide lamps during vegetative growth, plants will have shorter stems. If exposed to high-pressure sodium lamps, they will have longer stems.

Infrared light, which is invisible to human eyes, can also be used to help maintain plant height. It is used when the lights are off and is produced by heat lamps (which also emit some red light). A black cotton cloth will cover the heat lamp reflector, allowing the infrared rays to produce the desired effect while also capturing red light to avoid negating the effect. Even so, infrared light can also induce flowering and should really only be used during flowering.

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Heat can also affect stem growth. As the temperature rises, marijuana plants will naturally grow longer stems. At around 60*F (15*C), plant growth slows down and the stems tend to be thicker. At 80*F (27*C) you’ll notice that both buds and lower stems will start to stretch.

Buds that extend too close to a light might become airy or lanky. Some growers will mistakenly associate this phenomenon with “light burn.” But, this isn’t the real problem. What really happens is that the lamp’s heat creates an unsustainably hot atmosphere in the bud zone. Some solutions include using an air-cooled lamp that will prevent a large part of the meat from even entering the room. Likewise, water-cooled lamps will capture virtually all of the lamp heat so that buds can be very close to the light without the chance of burning.

Commercial greenhouses also use a method called temperature inversion. This basically entails keeping the temperature higher during dark periods and lower during light periods. Maintaining a temperature in the low 70’s (21-23*C) during the light period and increasing that temperature to around 80*F (27*C) at night will slow vertical growth and will not affect yield adversely.

Lack of adequate light will cause stem elongation. Seedlings will grow long, thin stems in an attempt to reach more light. To prevent this, supply a much more intense light regimen or at least put the seedling closer to the light source. If the seedlings have already stretched, try to support them using wooden skewers. After providing much more intense supply of light, the stems will fill out and will be able to support themselves on their own. Older plants will also stretch toward the light source if they are suffering from light deprivation. In this case, buds grow airy, they won’t tighten up, and they also have scant trichome coverage. Adding extra bulbs or moving the light closer to the plants can prove beneficial.

Pruning can also be utilized to decrease stem length. Excising the very top of the main stem forces the surrounding branch to grow. These ancillary branches will not grow as long or as tall as the main stem. You can also just bend the top branch until it snaps and hangs lower.

All top quality marijuana seeds are available in my marijuana seed shop. We ship seeds to the US, CA and many other countries. For any growing related question please visit the marijuana support page. Make sure to download my free grow guide.

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What is stretch and how can I minimize it?

Stretch is a term for the natural vertical growth spurt in early flowering. Marijuana will grow in height throughout its flowering phase, but the first 2 weeks of flowering will show the most dramatic change in height and internodal distance. Stretch can also occur in the vegetative phase.
Stretch is generally considered an unavoidable evil, but some gardeners prefer a bit of stretch to allow budsites to fill in adequately. Buds with perfect density can be grown by controlling stretch.
Encouraging stretch can be a good technique to prevent budrot in susceptible strains and massive colas. Elongated buds are less dense, and the humidity within buds is reduced.
Note: Males will typically stretch much more than females and are easily identified and pre-sexxed by their extra height.
Why is stretch a problem?
Stretch is a problem primarily in indoor grows because it greatly reduces yield. The problem stems from the limitations of artificial light and the plants adaptations to low light.
Stretch also produces tall plants with weak and spindly stems. The weight of the buds later in flower will require staking to avoid damage and falling over. Stretch may be a sudden problem for growers with limited ceiling height.
Light intensity vs internodal distance
Light intensity diminishes exponentially with distance under artificial light (the inverse squared law). Sunlight is not affected by distance and can penetrate deep into a canopy.
Marijuana requires high light levels (At least 30w/m2, preferably 50 w/m2) to thrive and produce high yields. A plant is at its optimum flowering height when all its bud sites are bathed in intense light (ideally the entire plant is equally lit, producing dense bud from top to bottom).
Stretched plants are tall and their lower bud sites receive exponentially lower lumens than top colas. Budsites that are not receiving intense light will not produce well, and often the light and extra plant height is wasted. Tall plants require more energy to pump water to its leaves and transport photosynthate from its leaves. This extra energy could have gone into flowering. Stretched plants can yield 30-50% less.
Lower bud sites that are not illuminated sufficiently will produce under-developed buds: airy or popcorn bud. Popcorn buds have lower dry weight, take much longer to trim, and often have less bag appeal.
How can I minimize stretch?
Note: Some of these techniques only apply to the stretch phase.
Use a compact strain
Indicas tend to have minimal stretch growing characteristics in flower compared to tall-growing Sativas. Hybrids may grow unevenly, or react to stress unexpectedly.
Keep light at the optimum distance
Low light levels will cause seedlings and plants to stretch and produce poorly.
.High light inhibits plant growth – plants tend to grow taller when there is less light.”
Use adequate spacing
Very high planting densities will encourage stretch. As the plant grows, its leaves will quickly overlap its neighbors. Eventually the sub-canopy will darken and lower portions of the plant will experience significant shading.
“Overlapping of plant parts reduces light intensity and changes light quality, resulting in light below plant canopies that is richer in near-infrared and far-red which encourages plant stretching.”
Pruning, FIM’ing and topping
Pruning plants in veg and early flower can effect the flow of auxins within the plant. Re-distributing natural growth hormones from terminal shoots to lateral shoots is a good way to slow height growth.
Note: Pruning in SOG systems is not recommended, as this promotes bushiness.
Use blue-spectrum light
Using MH light exclusively during vegetative and early flower phases will help keep internodal length shorter.
From: What do all of those lighting terms mean?
The light produced by metal halide lamps is in the white-blue spectrum, which encourages vegetative growth and “bushiness” while discouraging upward growth. This is the bulb to use in the first, vegetative phase of plant growth.
HPS bulbs are the preferred lighting source for flowering. However, most HPS bulbs have a harsh and limited light spectrum concentrated in the far red and IR that encourages stretching.
Growers have a variety of bulb options to increase blue light during the vegetative and early flowering phase:

  • Supplemental fluorescents
  • MH bulbs, or a mix of HPS to MH (3:1 recommended)
  • Conversion bulbs (MH bulbs that work with HPS ballasts)
  • Enhanced HPS
    Minimize night/day temperature fluctuations
    According to Cannabis Culture : (
    “Plant internodal length is directly related to the difference between day and night temperatures the warmer your day cycle is as compared to your night cycle, the greater your internode length will be. The opposite also holds true; the closer your day and night temperatures, the shorter your internodes will be.”
    Minimize stress
    Stretching can be a physiological reaction to a variety of environmental stresses (Low light, high humidity, low/high temperatures, transplant shock, leaf loss, etc). Maintaining optimum growing conditions is your best defense against stretch.
    Anti-stretch additives
    SuperBud is a popular additive to help minimize stretch and initiate flowering faster. See faq: What is Superbud?
    Bonza Bud (contains antigibberillins) shortens internode length while helping the predominance of female flowers.
    Growth retardants:
    Avoid hormones
    Some foliar sprays and additives can encourage stretch. Spraying Growth Plus (containing cytokines and vitamins) during early flower may encourage stretch. “Cytokinine – activates cell stretching…”
    Use side lighting (vertical bulbs)
    Untested. The Phototropic effects of side lighting may limit the amount of stretch: dark side of the stem grows more than the lit side of the stem. (
    Grower’s tricks
  • Use MH lights during vegging and the first 2 weeks of flowering (during the stretch phase) to minimize stretch.
  • Avoid high levels of Nitrogen during the stretch. Use a transition fertilizer ratio (2-2-2) during early flowering to maintain a medium level of Nitrogen.
    Note: Switching immediately to a flowering ratio from veg can result in premature yellowing. Remember to flush soil out/change the reservoir to remove any high-N fertilizers.
  • Use oscillating fans to help strengthen stems
  • ‘Julian contemplated a moment before throwing a new taunt back at the leggy woman.’
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  • ‘A tall leggy figure stepped in the light of the entrance to the bar, and Brian grinned.’
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  • ‘One, a leggy brunette in a polka dotted skirt, even winked.’
  • ‘When we met, I was a boisterous, headstrong, tall, leggy blonde.’
  • ‘‘I have recovered, of course,’ said the leggy model about her disastrous venture into Indian films.’
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What does leggy mean?

See a translation

Question 5 Jul 2019

Traditional Chinese (Taiwan) English (US) Question about English (US) Answers What are “disagrees”? When you “disagree” with an answer The owner of it will not be notified. Only the user who asked this question will see who disagreed with this answer. OKEnglish (US) It means that a person or animal has very long legs 0 likes 0 disagrees Share this question Newest Questions

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If you are like the majority of hydroponics growers, you try to do everything you ability to increase your overall yield. One of the most important things that you can do to influence your yield is actually increase the thickness of your stems. Unfortunately, if you do not have enough stem mass, you simply will not get the yields you want, because they will not be able to support the weight of your crop.
The significance of thicker stems is known to all hydroponic growers. The thicker your stems are, the more weight that they are able to hold. And the more weight that they are able to hold, the larger your yield has the potential to be.
Unfortunately, thicker stems do not happen by themselves. While there are some plants that have genetic advantages over others, thicker stems usually happen when you work hard to create them. Fortunately, there are a number of techniques and supplements any hydroponic grower can use to increase the thickness of their stems, and the overall health of their plants. One of the most vital anatomical features of your plant is the stem.
Thick, strong stems usually indicate that your plant has a great capability to produce very large, heavy yields. Thin stems that can hold a lot less weight probably mean you will not enjoy as good of a harvest season. This is why it is imperative for every hydroponic grower to do everything they can to ensure that their stems are as thick and strong as possible. But thicker stems just do not happen by themselves.
While you may have some genetic advantages in your plants, it is still up to you to work towards achieving those thicker stems that produce those fantastic yields. One of the most important anatomical features of your plants is the stem. If you have nice, thick, strong stems, it is usually a good indicator that you will enjoy a fairly large yield.
On the other hand, if your stems are a little thin or weak, then they just will not be capable to producing larger fruits. However, if you have suffered with thicker stems in the past, that does not mean that, you have to deal with in it in the future. In fact, there are number of methods that hydroponics users employ to get the kind of hardy, thicker stems that produce massive yields.
Here are just a few ways you can get the thicker stems that you need for a successful hydroponics garden:
Grow room Fan – The natural environment of a plant is not as still and quiet as a grow room. Plants like refreshing and rejuvenating themselves with constant flow of breeze that help them with lot of plant activity in return. You can help simulate this aspect of traditional growing by simply installing a small, inexpensive fan. Having an oscillating fan is also a must for any hydroponic garden because it will help circulate the air, which will help provide an optimal amount of atmospheric gasses to your plant.
A gentle breeze will actually force the plant to react in a way that creates thicker stems. Whenever the breeze from the fan puts pressure on the plants, it will respond by actually growing stronger, and creating thicker stems. Increase overall plant strength is by using a small oscillating fan against the plant.
Potassium Silicate – Potassium silicate is the most powerful supplement for creating thicker stems. Potassium Silicate substance actually affects the cells of your hydroponically grown plants, building them physically thicker and larger. The final result is overall larger, healthier plants and super strong stems. One of the key benefits of using potassium silicate is its ability to remove plant diseases.
A fairly good and appropriate amount of potassium silicate recommended by a reputable hydroponics company can help you increase your plants defence against mites, molds, and mildew. The thicker stems helps prevents the plants from pathogens. Potassium silicate should be among your essential hydroponic supplements. It actually affects the very cells and cell walls, creating thicker stems and overall stronger plants.
Roots Booster – Your roots are the whole foundation of your plant. Your plants root will be able to soak up all the nutrients in your reservoir efficiently if they have full and very complicated root systems. Building thicker roots will not only just lead to thicker stems, but will also lead to overall healthier plants. One of the simple and most efficient ways to essentially get those thicker roots for thicker stems is by using a root booster. The most efficient root boosters naturally contain plant growth promoting bacteria or the symbiotic bacteria.
These are bacteria are known to work symbiotically with the roots of the plants, increasing the root thickness and actually helping your plants make better use of different essential nutrients, particularly nitrogen. Your plant root zone is where your plants get the maximum amount of their nutrients, and if you don’t have large, fat, and complicated roots, your plants won’t be able to soak up all of the nutrients fairly. Thus, one of the smartest ways to help your plants make more efficient use of your hydroponic nutrients is by applying the root booster technique.
Grow Light Intensity – Work enough on your grow lights so that it provides your plants with all the lumens that they actually need to thrive which can be sufficient enough to get those stems to thicken. If there is no proper light in the grow room, you will not be able to get thicker and strong stems because your plant will thus not be able to produce enough carbohydrates through photosynthesis method to stimulate growth. Often weak stems are the indication that you are not providing enough light.
You should get a light measuring device that can make sure that the top canopy is receiving at least 3000 lumens of light. Most of the plants that have thin stems are simply the ones that doesn’t get enough light that they require. You can probably adjust your lighting fixtures according to your requirement, perhaps increasing the lights by placing the grow lights a little closer to the plants to ensure that they absorb at least 3000 lumens of light. This light alone might help the plants to create thicker stems. This is another measure that goes back to basics, but can be tremendously effective for getting thicker stems.

  1. Provide direct light: Just because a window seems bright from sunup to sundown does not mean it yields enough direct sunlight to grow plants. Seedlings need to be placed in a window that experiences six to eight hours of direct sunlight each day. Even plants that thrive outdoors in partial shade during the summer need direct sunlight to propagate seedlings.
  2. Provide artificial light: If your window of direct light falls nowhere near the needed six to eight hours, artificial light may be warranted. A variety of specialty grow lights are available for purchase, but you can certainly get by with an inexpensive fluorescent shop light. Use this light to provide at least 16 hours of light for your seedings per day. Enlist the help of a timer to make it easier to keep track of the exposure time without any additional effort.
  3. Adjust supplemental light: Lastly, your supplemental light source needs to be close enough to your plants so that they are not reaching out to grab it. Two to three inches from the top of the seedlings should suffice (make sure not to burn the leaves). A distance further then that will make the tiny plants stretch themselves, resulting in legginess.

Thicker Stems – Techniques for Hydroponics

One of the most important anatomical features of your plants is the stem. If you have nice, thick, strong stems, it is usually a good indicator that you will enjoy a fairly large yield. On the other hand, if your stems are a little thin or weak, then they just will not be capable to producing larger fruits.

However, if you have suffered with thicker stems in the past, that does not mean that, you have to deal with in it in the future. In fact, there are number of methods that hydroponics users employ to get the kind of hardy, thicker stems that produce massive yields.

Here are some of the most popular ways to get thicker stems on your plants:

Grow Room Fan – If you do not have one already, you should definitely have an oscillating fan in your grow room. It helps circulate the air, helping ensure a much more even distribution of the gasses that that help you plant grow in your grow room.

If you place the fan in the right place, however, it has the secondary benefit of helping to create thicker stems. Your stems will actually react to the gentle stress of being pushed by the fan by growing larger, much like a muscle can get larger through exercise. However, there is really no reason for this fan to be too intense. There is no benefit to have to contend with gale force wind every time you step into your grow room.

Potassium Silicate – One of the most effective hydroponics supplements for getting thicker stems is potassium silicate. This material actually increases cell mass within your plants, resulting in larger, thicker stems.

Another primary advantage of this kind of product is that it actually strengthens your plants against the kinds of diseases and infestations that can cause serious crop losses. By using a potassium silicate product, you are much less likely to walk into your grow room to discover that your plants have been overrun by a harmful pathogen.

Root Booster – If you have long had to deal with insufficient stems, the problem may very well lie in your root zone. Every hydroponic grower knows that all of your nutrient absorption happens at the root level. If your roots do not have the proper amount of mass, or they simply just are not complex enough, they are not going to make optimal use of your nutrient solution.

The most effective root boosters typically contain plant growth promoting bacteria. These are bacteria that are known to work symbiotically with plant roots, increasing root density and actually helping your plants make superior use of various nutrients, most notably nitrogen.

Light Intensity – This is another measure that goes back to basics, but can be tremendously effective for getting thicker stems. Something as simple as taking the time to reposition the lights might generate enough new carbohydrates within the plant to create the thicker stems that create large yields.

How to Control Stretching: Reigning in Cannabis Growth Spurts

There are few things more frustrating than an overcrowded grow room. “Stretching,” the term used to describe the rapid growth of cannabis stems, is a natural part of the vegetative stage and is influenced by plant genetics, among other variables.

Unfortunately, stretching is a common perpetrator of low yields and lanky plants, resulting in teetering, physically unstable crops. Despite the threat it poses, stretching can be controlled by first examining the factors influencing its growth, then creating protocol to sidestep these issues. Controlling cannabis stretching requires an understanding of how plants interact with both their internal and external environments.


There are several reasons why plants stretch, one of which has to do with the strains themselves. Genetics plays a pivotal role in determining the eventual height of sativas, indicas and hybrids. Whereas most indica strains are bred to grow shorter and bushier, sativas often experience significant stretching, sometimes growing six feet or higher in some breeds.

While stretching isn’t harmful in and of itself, dramatic stem growth carries the potential of significantly lowering the crop’s final yield between 20-30% overall. When considering strains for your next home grow, research the common height of each variety you plan to grow in order to gauge whether or not the strain experiences a dramatic flowering stretch.


One of the main culprits of inordinate stretching of cannabis plants is lack of light exposure. Plants that are too far away from an adequate light source will respond by spurring stem growth to move themselves closer to the lamp. Especially in the presence of many other plants, sparse lighting can easily cause a grow room to become severely overcrowded, throwing off the steady progress of your crop and the ratio of distance between bulbs and plants.

In response to this issue, be sure to provide enough light to quell stem growth. At the same time, you don’t want to position your lights too close to your plants, as this will also result in overstretched stems and in some cases, lost yield.

In addition to distance between the source and the plant, the kind of light being used also holds influence over the amount your crop will stretch. Orange and red light encourages stretching and results in thinner, taller stems. Conversely, blue light stimulates thicker stem growth and a shorter height therein. When a strain is ready to enter the vegetative stage and undergo its most drastic period of stretching, metal halide lamps can be used to discourage extra-long stems.


Heat is another pivotal element that can determine how much plants will stretch during vegetation. Temperatures reaching over 27 degrees push stems to grow longer and longer and will propel sativas to their full height potential. Heat lamps that are positioned too close to the plants creates an intolerable environment that will rouse tall, wobbly plants, which are likely to fall over and potentially lose flowers in the process.


There are numerous variables that can lead to plants stretching beyond what is normally expected from the strain. Significant environmental stressors resulting from transplant may cause the plant to go into shock. This will then trigger a reaction, causing it to stretch. Cannabis plants that are not properly cultivated under decent conditions or aren’t receiving satisfactory nutrition will respond in a number of adverse forms, including stretching.

Crops that are not spaced far away enough from one another are likely to stretch as a result of competition for resources. Due to extreme proximity, plants will fight each other to reach the light, forcing growth throughout the crop.


Flowering stretch, you guessed it, takes place when you switch your plants over from veg to bloom. This is a completely normal response as your plants prepare themselves to support the weight of their buds.

How much a plant stretches at the beginning of flowering varies a lot; some plants might double in height while others only grow a few centimetres. There are two main variables, however, that can give you at least some idea of whether your plants will stretch during bloom, and how much. These are:

• Strain: Genetics have the biggest impact on your plant’s size. Generally speaking, sativa strains stretch more than indicas and tend to develop long, lanky stems.

• Lights: Certain lights, like HPS, are more likely to encourage stretching. Moreover, large distances between your canopy and your lights will cause plants to stretch as they attempt to get closer to the light source.

The flowering stretch usually lasts for the first two weeks of the phase. To minimise stretching, keep your lights between 10 (for CFL) and 30 centimetres (for HID) from your canopy. Also, stick to indica strains if you’ve got a smaller grow space.


In many cases, you can account for at least some stretching to occur in the flowering stage of your cannabis plants. With this is mind, it’s helpful to establish a plan in case you’re strain ends up growing higher than you imagined. If the information is available, obtain the average reported height of your strain and compare it to your grow room dimensions, considering the necessary distance between bulbs and plants.


While outdoor grow-ops benefit from the presence of the open air to naturally limit stretching, indoor operations are tasked with the tough assignment of maintaining air circulation inside a closed space. Sufficient airflow helps cannabis stems strengthen and grow thicker, rather than taller. This way, plants still grow vigorously, without reaching nerve-wracking heights.


For those cultivators looking to get their hands dirty, there are physical intervention methods that can be taken to reduce over-stretching. Similar to the natural effect wind has on cannabis plants, manually bending the leaves and stems will cause tiny tears in plant tissue that will cause the plant to focus its attention on stem regeneration instead of vertical growth.


Topping is a form of manual intervention on cannabis to affect its yield, shape or size. In essence, topping is the process of cutting of a new, actively growing node from your plant in order to reduce its size and create a “v” shape that will then form two colas. Topping can be an effective measure for combating stretching, but it’s important not to top once the flowering stage begins.

In most cases, unexpected stretching from cannabis plants won’t destroy your yield entirely. In fact, stretching can actually help to increase your yield. For cultivators with sizeable grow rooms that can sustain tall plants, stretching may actually increase a strain’s total yield with more vertical surface area for colas to form. Either way, stretching can be easily prepared for in advance and there are a number of different solutions to help with this all-too-common problem.

How to avoid stretching cannabis plants

One of the potential problems, that cannabis growers face, is stretching stems. This phenomena occurs for numerous reasons. One of which the grower has very little control over: Genetics. For example, some sativa strains reach for the sky and grow to massive heights both indoors and outdoors, making stem stretching an inevitability.

However, with strains that are less prone to stem stretching, there are several ways to prevent or reduce it from occurring.


This so called stretching is really a growth spurt, that plants usually go through during the vegetative phase and also early on in the flowering phase. Not all growers are opposed to stretching, as it can be seen as a useful factor in ensuring the even distribution of flowers over a plant.

Also, stretching early in the vegetative phase may be a factor, that acts against bud rot in strains, that have a tendency to be weak against it, as the distance between flowering points may reduce humidity.

However, stretching isn’t all good. Stem stretching means a taller plant with a weaker stem. If your goal is to fully load your plants with large, towering buds, it will be susceptible to bending and damage if the load gets too much.

This can obviously end very badly for both the plant in question and the grower if no external support is used. Another downside to stem stretching is that certain plants will outgrow their designated grow space and become limited by the ceiling.

Let’s take a look at some ways to prevent or reduce stem stretching.


Air circulation may act as a small, but positive stressor, that might reduce stem stretching. Adequate air circulation will blow against the plants and force the development of stronger and possibly wider stems as an adaptation.


If you plant your crop too dense, eventually overcrowding will take hold. As your plants start to develop leaves, they will form a layer, that obstructs light from accessing the lower regions of the plants.


Some strains are genetically very short and compact, but still more than capable of pumping out some good size and excellent quality buds. Indica strains bare the characteristics of being shorter and more bush-like in nature, whereas sativas grow extremely tall in some cases. An autoflowering indica strain might be the best choice when wanting to reduce stem stretching.


Different wavelengths of light affect the growth of cannabis plants. Yellow and red light sources are often used during the flowering stage of the grow cycle, as they encourage plants to grow tall.

However, blue light is primarily used during the vegetative phase, as plants react by growing shorter with bigger leaves. Therefore blue light is optimal when it comes to the prevention of stem stretching.

Inadequate amounts of light will also lead to stem stretching, as seedlings will keep growing taller and thinner in an attempt to grow closer to the light source, so make sure your plants are receiving the proper amounts of light at each stage in the grow cycle.


Controlling the difference between daytime and nighttime temperature within the grow space will allow prevention of stem stretching. The closer these two temperatures are, the closer the internodes of the plant’s stem will be. This means a shorter and stronger stem.

6 Ways To Reduce Marijuana Plants From Stretching

Cannabis plants that grow too stretchy and reach for the sky are unlikely to deliver a hefty marijuana harvest. We’ve got 6 tips to suppress shoot stretching that will help you succeed in cropping a major stash.


Every grower wants to see a cannabis garden packed with trophy colas of dank marijuana come harvest. Excessive plant stretching, whatever the cause, is guaranteed to rob you of this magnificent sight. Lanky cannabis plants with huge internodal spacing are to be avoided at all costs. Yields will be low and bud quality will likely be the same.

Tall, stretchy plants can even be too much of a handful for some master growers. Moreover, for the average home grower or micro-grower, crop space is at a premium. That’s precisely why we’ve put together 6 easy steps to help you prevent marijuana plant stretching from becoming a problem in your grow-op.


The best way to avoid stretchy cannabis plants is to select a high-quality indica-dominant strain to cultivate. Cannabis strains derived from high altitude mountain Kush varieties have naturally evolved a bushy, tight internodal spacing structure. Indica strains are renowned for their squat and stocky appearance and come highly recommended for smaller grow spaces. Old school classics like Northern Lights and Afghan Kush have very short distances between nodes.

At the opposite end of the cannabis spectrum are the sativa strains. Tall, slender and sparse branching sativa-dominant marijuana is less well-adapted to indoor cultivation. Even with early training and pruning, sativa sativa varieties will still stretch significantly during the bloom phase. Many growers will cultivate late blooming Haze vines on a 12/12 schedule from seed in an effort to limit stretching.

Hybrids are often the best alternative. The very best will display a blend of the most desirable indica and sativa characteristics. The Skunk family fits the bill nicely. Super Skunk for a couchlock effect; Lemon Skunk for the high flyers with a taste for citrus; Cheese for the connoisseurs. There really is a Skunk for every kind of stoner.

Lest we forget the “autos.” Most autoflowering cannabis develops just a single main cola with few side branches, excluding XL Super-Autos. Given that most next-gen hybrids usually peak at about 1m in height both indoors and out, autos are probably the simplest solution to plant stretching problems. It’s just not an issue with them. Autos are not for everyone, but for the beginner grower, they are the most forgiving cannabis plants to crop.


Fans, fans and more fans! Use an intake fan to draw in fresh air. An extractor fan is a must to suck out the stale air. A pedestal fan (or at very least, a clip-on fan) is another necessity. Try to create a gentle breeze effect on your plants. Stems will be weak and later in bloom, branches may snap without wind to toughen them up from vegetative growth onward. Don’t forget to use ducting and to connect a carbon filter to the extractor fan to eliminate odour.


Get this right and you will reduce stretching in marijuana plants with minimal effort. Blue/white light is best for seedlings and vegetative growth, while the more orange/red spectrum is suited to flowering. To reduce stretching and to keep internodal spacing to a minimum, it’s best to use cool blue/white spectrum lighting that can be positioned close to the plant canopy.

According to old-school cultivation methods, you could use MH or White CFL for vegetative growth, then switch to HPS for flowering. Nowadays, some growers tend to opt for Full Spectrum LED to support the complete lifecycle, but this is still a bit “futuristic” in terms of feasibility.


Temperature is a key growth collaborator and inhibitor. Above 29°C spells trouble for cannabis. Too cold and plants will be stunted and dwarfed, too hot and plants will be spindly, burnt and even turn hermie. Heat stress in the upper canopy of the cannabis garden can do more than just burn foliage.

Worst of all, high heat makes shoots grow thinner and stretchy. This turns top colas into worthless, fluffy buds. Growers can avoid this by hanging lamps the correct distance from tops and by maintaining optimal temperatures from seed to harvest.


An overcrowded SOG won’t do you or the plants any favours. Don’t get greedy. If plants are spaced so close together that they are touching and leaves are shading most branches, the harvest will suffer. Plants will compete for light and race up vertically to survive. Long, thin stretchy colas don’t take home any trophies. They just don’t develop properly. Nobody wants a 50cm long stick of fluff or leafy popcorn buds for a stash.

6. ScrOG

The most effective method to maintain an even plant canopy that results in a harvest of big fat buds is the ScrOG. This technique is usually applied in combination with topping, LST or supercropping during vegetative growth. Deploying a screen and weaving shoots to fill out the grid is the best way to eliminate stretching as a problem.

The wildest of Hazes can be tamed by a ScrOG. That being said, this one is for the more experienced cultivator. Master at least one of the topping, LST and supercropping trio before dropping a ScrOG on the grow-op to combat plant stretching.

Written by: Top-Shelf Grower
Veteran cannabis cultivator originally from Dublin, Ireland and currently on the loose in southern Spain. 100% committed to Top-Shelf reporting until captured or killed.

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