How do tomatoes pollinate

If you are new to greenhouse gardening you may not have experienced issues with growing tomatoes.

However, if you grow these plants long enough indoors you are sure to experience some struggles.

Identifying the source of these struggles early on makes the difference between a robust harvest and a so-so harvest.

The good news is, there are remedies for the issues and ways to ensure a successful harvest.

Here are some common issues that occur when growing tomatoes in a greenhouse:

Contents

4 Common Issues Growing Tomatoes In A Greenhouse

1. Choosing the wrong variety

For the best success, it is essential that you plant only tomato varieties that are bred for greenhouse growing – not field or garden growing.

Choosing the right variety gives you a head start to success when growing in a greenhouse.

The most widely used variety in greenhouse growing in the United States is the Dutch hybrid beefsteak-type tomato: Trust.

If you like heirloom varieties the hybrids Marneo (like Cherokee Purple) and Margold (like Striped Germans), are best.

2. Planting too close together

While the tendency might be to cram as many tomatoes into your greenhouse as possible, this is not a wise option.

Tomatoes that are grown both in a greenhouse as well as outside need space for air circulation. Tomato plants are prone to foliar diseases including blight, and leaf spot and require good air movement.

To be safe give each tomato plant at least four square feet of space.

3. Watering issues

Full-size tomato plants require two to three quarts of water per day when it is sunny. The water needs to be delivered at regular intervals. Irregular, or over-watering, is the single biggest cause of blossom-end rot.

One of the advantages of greenhouse gardening is that you have control over the irrigation. Just be sure to use drip irrigation at the roots, not overhead irrigation that leaves the plant’s foliage wet and susceptible to disease.

4. Lack of pollinators

One of the biggest challenges of growing tomatoes in a greenhouse is the lack of wind or bugs, such as bees, to help with pollination.

Without pollination, there is no fruit.

To overcome this, gardeners have developed a creative method of hand pollinating plants using a paintbrush.

Keep in mind that tomatoes contain both male and female parts and are self-pollinating. If left alone, tomatoes will have a 20% – 30% fruit set rate without the help of pollinators or hand pollination.

Over time, gravity causes the pollen to fall from the male portion of the flower to the female portion.

However, to have a higher percentage of fruit set, you can hand pollinate plants.

How To Hand Pollinate Tomatoes

Follow the steps below to hand pollinate your greenhouse tomatoes using a paintbrush.

Paintbrush Pollination Technique

When a pollinator visits a tomato flower, they use vibration to make the pollen fall from the male flower part (anthers) to the female flower part (stigma). Duplicating the vibration is a great way to encourage pollination.

Using a small artist brush is a great way to hand pollinate tomato plants. The brush tip simulates the nectar gathering tool of pollinators in nature.

Materials

  • None

Tools

  • Small Paintbrush

Instructions

  1. Gently lift up the tomato flower.
  2. Rub the paintbrush on the inside of the flower lightly back and forth. This encourages the pollen to drop down to the female portion of the flower.
  3. Hand pollinate around midday every two to three days. Flowers will wilt and fruiting will begin when pollination is successful so keep a keen eye out for this.
  4. Be sure to use a different brush or wash the original brush in alcohol before moving on to a different variety. If not, you will have cross-pollination.

More ways to hand pollinate tomato plants

Your finger – gently tap on the top of the flower in a high-frequency manner

Electric toothbrush – mimics the vibration of a bee

Cotton swab – great surface area for collecting pollen

More ways to pollinate tomatoes in a greenhouse

Open the doors and windows – If conditions allow, you can open doors and windows to let in natural pollinators and wind that will help with the pollination effort.

Play that funky music – Just having a radio playing in your greenhouse can help pollinate tomatoes. The micro-vibrations will cause the pollen to drop.

Blossom set spray – Also known as blossom set hormone, blossom set spray is available in most garden centers or from this page on Amazon.

This spray contains a cytokinin hormone that promotes cell division. They help tomato plants grow fruit in marginal conditions such as in a greenhouse where there are no natural pollinators.

Be sure to use only when the first blossoms are starting to open. Spray the blossoms and the attached leaves until the spray is dripping. Use in one week intervals until you see that all the blossoms have set fruit.

More Tomato Growing Tips

Take a look at more of our tomato growing articles below:

10 Pro Tips For Growing Tasty & Abundant Tomatoes

My Homemade Tomato Fertilizer Recipe Perfected Over 30 Years

How To Grow Upside Down Tomato Plants

Pollinating Greenhouse Tomatoes with Vibrators, Blowers

Hanna Y. Hanna

The flower structure of most commercial tomato cultivars assures self-pollination and virtually eliminates the opportunity for outcrossing. Pollen is shed within the individual flowers during blooming when there is a strong enough vibrating force, such as wind, to shake the plant and the flower. In the absence of naturally occurring wind in the greenhouse, tomato flowers have to be vibrated by some mechanical means, such as electric vibrators, air blowers or bumblebees, to release the pollen.
Currently, larger greenhouse tomato producers use laboratory-reared colonies of bumblebees to pollinate the crop. In smaller operations, however, bumblebee pollination is not a good choice. At any given time, opened flowers are too few in number to supply enough pollen for the foraging bees. As a result, bees visit opened flowers repeatedly, destroying the protective anther tube (the pollenproducing parts of the flower) and damaging the pistils (the female reproductive organs).
The majority of greenhouse tomato operations in Louisiana and other southern states are small. Thus, handheld electric vibrators or air blowers may be the best pollinating tools for these operations. This study was conducted to compare the effectiveness and economics of these tools as pollinators in small greenhouse tomato operations.
Studies were conducted in a 30-foot by 96-foot double polyethylene greenhouse at the LSU AgCenter Red River Research Station in Bossier City. Tomato varieties Caruso and Trust were raised in 15-gallon polyethylene bags filled with ground pine bark. Four tomato plants were planted in each bag in two parallel rows, and 30 plants of each cultivar were grown under the same conditions for testing the effect of each method of pollination on tomato yield and fruit characteristics.
Tomato plants in the blowerpollinated treatment were vigorously vibrated on Monday, Wednesday and Friday of each week. Vibration took place around noon using an Echo P.B.- 1000 air blower. Vibration started at the beginning of blooming and continued for 13 weeks. The blower was held approximately 15 inches from the tomato plant and directed toward the flower clusters as the operator walked between the tomato rows.
Flower clusters in the electric vibrator treatment were vigorously vibrated by touching the flower stalk for about two seconds. Pollination was conducted using a Dutch-made electric vibrator on the same days and time as the blower.
Two additional greenhouses having 640 plants each were pollinated for 13 weeks by the same persons using either tool to determine pollination time. Cost of pollination by either tool was calculated based on a 13-week period at $7 per hour per person.
Tomatoes were harvested from each treatment at the pink stage three times per week for 13 weeks, and plant yield was determined. Mean fruit weight and diameter were also determined on a sample of 10 marketable fruits collected at random around mid-harvest. Seeds were extracted from the sample fruits, and the mean number of seeds per fruit was determined.
Test results indicated vibratorpollinated plants of each variety produced greater marketable yield than did blower-pollinated plants. Within varieties, marketable yield was greater and yields of culls were lower with vibrator-pollinated plants. Fruit weight and diameter and the number of seeds per fruit were greater in vibrator-pollinated plants. Marketable yield of Trust was greater in the first year, but yield for Caruso excelled in the second year.
The time needed to pollinate 640 plants for 13 weeks was 7.13 person hours using the air blower and 11.75 person hours using the electric vibrator. Labor cost for pollination was $49.92 for the air blower and $82.25 for the vibrator. The yield reduction using the air blower for pollination was not offset by the savings in labor cost.
We conclude that smaller greenhouse tomato growers should use the hand-held electric vibrators to pollinate their crop for maximum fruit yield, size and profit.
Hanna Y. Hanna, professor, Red River Research Station, Bossier City, La.
( This article was published in the winter 2005 issue of Louisiana Agriculture.)

Gardening tips: how to hand pollinate tomatoes for larger production of your container garden. Many gardeners leave pollination to the bees, but if you want to see the best harvests, you can take matters into your own hands.
In this video I am going to show you the best way to hand pollinate your tomatoes. All you need is a electric toothbrush and a few minutes of your time.
Many edible plants such as tomatoes are self-fertilizing or self-pollinating. This means that you only need one plant in the garden for fruit to set. In the case of tomatoes, the male and female parts are contained in the same flower. This truly makes tomato plants a top contender for container gardening.
Self-pollinating plants will produce without any intervention on your part, but you can help nature along to really reap the rewards. Wind and bees normally move the pollen around the plants, letting pollination occur, but what happens when nature doesn’t cooperate? Poor pollination happens all too often. High temperatures, humidity, and too much moisture can severely hinder your crop. So why not take matters into your own hands?
We all spend hours in the garden planting and caring for our little green friends, so I say lets go the extra step and pollinate by hand. Hand pollination of self-fertile plants is easy and does not require much time or money. All you need is an electric toothbrush and you are ready to hand pollinate. Just like the wind or a bee, the vibrations from the toothbrush loosen the pollen from the flower and allow pollination to occur. Simply turn on the toothbrush and gently place it behind the open flower. This will distribute the pollen to the flowers stigma. You will often see puffs of pollen shoot out of the flower when you do this. You should see the results of your hand pollination in a day or two. I like to repeat this process every other day for the best results.
If you are like me and you want to get the most out of your garden, then try to hand pollinate your tomatoes. I am sure that once you try it you will never go back. For more gardening tips and projects visit my blog http://www.getforked.ca .

Unpollinated tomato blooms start to shrivel and fall from the plant.

A lot of questions and calls come in every year about tomato plants not setting fruit. They look great and flower, but nothing happens beyond that. Unfortunately, the problem is usually not a disease or an insect — those can be controlled. This particular issue can be blamed on Mother Nature.

First, here’s a brief horticultural lesson. Tomatoes are self-pollinating, meaning they have flowers that contain both the male and female parts, so more than one plant is not needed for reproduction. The pollen falls within the flower to pollinate itself. That doesn’t mean insects and wind aren’t important, though. They can help pollinate self-pollinating plants; for example, when bees light on the yellow flowers, the buzzing of their wings helps to shake the pollen off into the flower.

All of this can be perfect and you might still be faced with tomato plants not setting fruit. Here’s why: high temperatures.

When temperatures rise above 85 to 90 degrees F (depending on humidity) during the day and 75 degrees F at night, pollen will become unviable. Humidity can also come into play. In the extreme humid regions of the U.S., pollen may become so sticky that it does not fall. On the other end of the spectrum, in the arid regions, pollen may become so dry that it does not stick to the female part of the flower. Many gardeners try to gently shake the plant to encourage pollination, but a lot of times it is just not going to work.

If you’re faced with tomato plants not setting fruit, the best thing to do is to keep the plants healthy and fertilized with plant food, such as Miracle-Gro® Shake ‘n Feed® Tomato, Fruit & Vegetable Plant Food. The plants will start to produce again when the weather becomes favorable. Note, though, that heirloom tomatoes can be even fussier about temperatures than most hybrid tomatoes, and in some areas will wait until late summer or early fall to start setting fruit.

There are tomato varieties that will set more fruit than most in the heat (although extreme heat will inhibit most all of these plants from setting fruit). Heatmaster and Solar Fire are two of these varieties. For more, check out the full range of Bonnie Plants’ heat tolerant tomato varieties. Also be sure to consult our Tomatoes page for more info on planting, growing, and caring for tomato plants.

If you’re still stumped about why your tomato plants won’t set fruit — or have another question about growing tomatoes — visit our Ask an Expert page. Happy growing!

If you have put a lot of care into growing tomato plants from seedlings, then you know how frustrating it can be to see the flowers fall of the plant as they get older. I have seen this happen myself, and I wondered what causes it, so I did some research on the subject.

So, why are your tomato flowers breaking off the plant? A lack of proper pollination will cause tomato flowers to break off the plant without fruiting. This can occur for several reasons, including a lack of pollinators or extreme levels of temperature and humidity. Too much fruit or an imbalance of nutrients in the soil can also cause flowers to break off the plant.

Let’s go into a little more detail about why the flowers might be breaking off of your tomato plant, along with how you can treat the problem. Then we’ll look at preventative measures you can take to get the best tomato harvest possible.

Lack of Pollination

A lack of proper pollination will eventually cause your tomato flowers to fall off the plant. Tomato plants are self-pollinating, which means that a flower contains both male and female parts.

However, self-pollination does not mean automatic pollination. Tomato plants still need pollinators and correct environmental conditions to pollinate the flowers and produce fruit.

Extreme Temperature or Humidity

Extremes in temperature or humidity can prevent proper pollination, even if pollinators such as bees are present and doing their work.

Extreme heat or humidity can prevent pollination and ultimately cause the tomato plant to drop these flowers.

If daytime temperatures go too far above 85 degrees Fahrenheit, then pollination will be inhibited. The same goes for nighttime temperatures above 75 degrees Fahrenheit. This will eventually lead to the tomato plant dropping the flowers.

Of course, if temperatures get up to 105 degrees Fahrenheit, this can cause immediate dropping of the flowers, as the plant shifts focus from reproduction to survival.

At the other end of the spectrum, cooler temperatures will also prevent pollination. If nighttime temperatures drop below 70 degrees Fahrenheit, then pollination will be inhibited.

If nighttime temperatures drop below 55 degrees Fahrenheit, then the plant may immediately drop its flowers. So, keep an eye on the weather forecast, and use covers to keep your tomato plants warm overnight if necessary!

Extremes in humidity levels can also prevent pollination of tomato plants. If the humidity is too high (the air is sticky), then the male part of the flower will not be able to release its pollen.

If the humidity is too low (the air is dry), then the male part of the flower will release pollen, but it will not stick to the female part of the flower.

Both of these situations will prevent pollination, and can eventually cause the plant to drop its flowers. An ideal humidity range for pollination is 40 to 70% humidity.

Lack of Pollinators

Even if the temperature and humidity levels are spot-on, a lack of pollinators can prevent your tomato flowers from being pollinated. Even self-pollinating flowers on tomato plants need something to “buzz” or vibrate the flowers, which causes the male part to release pollen onto the female part.

Usually, this ends up being some type of bee, although other insects, birds, or even wind can do the job. Unfortunately, bee populations have taken a hit in many areas in recent years.

This bee is busy pollinating flowers for you.

The use of pesticides will kill or repel the bees, so if you use pesticides in your yard, then consider using other methods to bring the bees back. You might also have to politely ask your neighbors to refrain from using pesticides, especially if they notice a lack of bees.

Planting plenty of flowers near your garden will also help to attract bees to your yard, where they will hopefully pollinate tomatoes and other plants in your garden.

How to Pollinate Your Tomato Plants

Of course, you may not have success in bringing bees back to your yard to pollinate your tomato plants. In that case, you will have to do it yourself.

One popular method is to use an electric toothbrush to “buzz” the back of each flower on the plant. You can also use a tuning fork if you want!

A tuning fork can vibrate just like an electric toothbrush – perfect for pollination by hand!

This will simulate the flapping and vibrating of a bee’s wings, and cause the male part of the flower to release its pollen. You will know it is working when you see a puff of pollen released from some of the flowers.

You can also use a toothpick, pencil, stick, or cotton swab to pollinate. Simply use the toothpick to push the flower out of position. Then, let it go, so that it “springs” back into place. The movement will cause a vibration and the male part should release pollen.

As mentioned above, temperature and humidity are factors in pollination, so make sure that you go out to hand-pollinate when the temperature and humidity are right. Again, the weather forecast is your friend!

The best time to pollinate is within a couple of hours of noontime. If the forecast calls for hot and humid weather, go out to pollinate in the morning or evening, when temperatures are cooler.

Too Much Fruit

You may be in the situation where your tomato plants have already been properly pollinated, and some of the flowers are starting to produce fruit. It is possible to have too much of a good thing, and if this is the case, then some of the flowers may start to drop off the plant. Let’s find out why.

Why Too Much Fruit is a Problem

First of all, your tomato plant can only support so much fruit in a season. There is a limit on how much water and nutrition the root system can pull up from the soil to the fruit. There is also a limit on how much sunlight the plant can absorb for photosynthesis.

In short, a tomato plant can only produce so much energy in a season, and this will limit the amount of fruit that it can support to maturity. If too many flowers are pollinated, then the plant will drop some of them off. The reasoning is that twenty perfectly ripe tomatoes are better than forty half-ripened ones.

Water and nutrition are not the only limits for how much fruit a plant can produce. The fruit is held by branches off the main vines of the tomato plants.

If too many fruits on one branch grow large, then the branch can bend or snap, which will cause all of the fruit to be lost. Too much fruit can even cause the whole plant to fall over or snap the stem. To learn more, check out my article on how to support your tomato plants.

Too much fruit on a tomato plant can cause damage to stems or branches. This one looks fine though.

In short, if you are losing flowers but have fruit on your plant, then take comfort in the fact that your tomato plant is too successful, and so it needs to slow things down a bit.

How To Solve The Problem Of Tomato Plants Dropping Flowers

If you want to allow your tomato plant to set even more fruit, there is one way to do just that. When you see some of the early flowers blooming, pinch them right off the plant. This will encourage the plant to focus its energy on root and vegetative growth, resulting in a stronger plant.

Stronger stems and branches will be able to support the weight of more tomatoes, and stronger roots will be able to provide the water and nutrition for those tomatoes. It is a short-term sacrifice for a long-term gain.

Nutrient Imbalances

It is possible that the flowers are falling off of your tomato plant because of a nutrient imbalance. This problem is not as common as lack of pollination or excessive fruit set, but if you think it could be a cause, then read on.

Nitrogen: Too Much of a Good Thing?

Nitrogen is an essential nutrient for plant growth, and it helps plants to green up. That is, nitrogen promotes vegetative growth: vines, shoots, and leaves.

Having plenty of nitrogen in the early stages of growth is a good thing. Having too much nitrogen in later stages can prevent flowering, since the plant continues to focus on vegetative (green) growth. For more information, check out my article on low-nitrogen fertilizers.

Avoid adding heavy nitrogen levels to your garden soil, and make sure to use a balanced fertilizer that also contains phosphorus and potassium. Speaking of which, let’s also discuss those nutrients.

Phosphorus: Necessary for Flowering

Phosphorus is another essential nutrient for plant growth. A lack of phosphorus will prevent flowering, so make sure that your fertilizer contains enough phosphorus.

A tomato will produce flowers like these if it has enough phosphorus.

If add your own compost made from grass, leaves, food scraps, and manure, then you will likely have plenty of phosphorus in your soil.

Potassium: Good for Fruiting

Once your flowers are pollinated and the plant begins to set fruit, it will need plenty of potassium to ensure that the tomatoes are large and ripe at harvest.

You need enough potassium to get healthy, ripe tomatoes at harvest.

Potassium is found in most garden store fertilizers or in a compost mix that you make yourself.

Calcium: A Lack Causes Blossom End Rot

One final note about nutrients: if you have a lack of calcium in your plants, then the fruit will have brown or black spots on the bottom, known as blossom-end rot. This can occur if there is not enough calcium in the soil, or due to uneven watering.

This tomato has a tiny patch of blossom-end rot. It can get much worse than this.

Calcium deficiency can also occur if there is a nutrient imbalance in the soil. For instance, too much magnesium can block the uptake of calcium, so be careful when adding Epsom salts to your soil! For more information, check out my article on calcium deficiency and my article on using Epsom salt for growing tomatoes.

To confirm any nutrient deficiency in your soil, you can send your soil away for a soil test. For more information, check out my article on testing your soil.

Other Causes of Tomato Flowers Breaking Off

There are a couple of other potential issues that may cause the flowers to break off of your tomato plants: disease or pests.

Disease

Bacterial or fungal diseases can stress your tomato plants and cause them to drop their flowers. Planting tomatoes in the same part of your garden every year can promote growth of diseases, so be sure to practice crop rotation to prevent this.

Also, when watering your plants, be sure to water close to the ground, not from above. This is especially true if you water in the evening, after work.

If the leaves get wet and stay wet, then they can grow fungus. If you water in the morning, then the daytime heat and the sun will dry out the leaves and soil to prevent fungus growth or root rot.

Black spots on the leaves, stems, or fruit of your tomato plants are a sign of many serious diseases. For more information, check out my article about black spots on tomato plants.

Be sure to water evenly, since uneven watering can cause calcium deficiency and blossom-end rot in your tomato plants – even if there is plenty of calcium in your soil!

Pests

Pests such as insects, rodents, or other creatures can put pressure on your tomato plants and cause them to drop their flowers due to stress.

Since pesticides can kill or repel bees, your best bet is to use organic methods to fight pests. For instance, you can release ladybugs into your garden to eat aphids if you see them on your plants. For more information, check out my article on how to get rid of aphids in your garden.

Aphids are a real pest in your garden … … but aphids are no match for ladybugs.

Beneficial nematodes will also act as parasites to many common garden insect pests.

You can also use companion planting to put plants in your garden that will repel pests that normally go after tomatoes. For instance, planting marigolds is thought to protect tomato plants from pests in the soil that go after the roots.

Conclusion

By now, you should have a good idea of what is causing your tomato flowers to break off the plant. Hopefully, you also have an idea of how to treat the problem this year, and how to prevent it in future years.

I hope that this article was helpful. If you have any questions, or any tips that worked well for you, please leave them in the comments below.

Steps To Pollinate Tomatoes By Hand

Tomatoes, pollination, honeybees, and the like may not always go hand in hand. While tomato flowers are typically wind pollinated, and occasionally by bees, the lack of air movement or low insect numbers can inhibit the natural pollination process. In these situations, you may need to hand pollinate tomatoes to ensure pollination takes place so your tomato plants bear fruit. Let’s look at how to pollinate tomato plants.

Can a Tomato Plant Pollinate By Itself?

Many plants are self-fertilizing, or self-pollinating. Edible plants like fruit and vegetables with self-pollinating flowers are also referred to as self-fruitful. In other words, you can plant just one variety of the plant and still get a crop from it.

Tomatoes are self-pollinating, as flowers are equipped with both male and female parts. One tomato plant is capable of producing a crop of fruit on its own, without the need of planting another one.

Nonetheless, nature doesn’t always cooperate. While wind normally moves the pollen

around for these plants, when there is none or when other factors, such as high temperatures and excessive moisture or humidity occur, poor pollination may result.

Tomatoes, Pollination, Honeybees

Honeybees and bumble bees can be sufficient substitutes for moving pollen on tomato plants. While planting a myriad of bright-colored plants in and around the garden can entice these helpful pollinators, some people prefer to maintain nearby hives. This practice is dependent on your personal needs and preferences.

How to Pollinate Tomato Plants by Hand

Another option is to pollinate tomatoes by hand. Not only is this easy but it can be quite effective. Pollen is normally shed from morning to afternoon, with midday the most optimal time to pollinate. Warm, sunny days with low humidity are ideal conditions for hand pollinating.

However, even if conditions are less than ideal, it never hurts to try anyway. Oftentimes, you can simply shake the plant(s) gently to distribute the pollen.

However, you may achieve better results by giving the vine a little vibrating instead. While you can purchase commercial pollinators or electric vibrator devices to hand pollinate tomatoes, a simple battery-operated toothbrush is really all you need. The vibrations cause the flowers to release pollen.

Techniques for hand pollinating vary, so use whatever method works best for you. Some people simply place the vibrating device (toothbrush) just behind the open flowers and gently blow on or shake the plant to distribute the pollen. Others prefer to collect the pollen in a small container and use a cotton swab to carefully rub the pollen directly onto the end of the flower stigma. Hand pollination is usually practiced every two to three days to ensure pollination occurs. Upon successful pollination, the flowers will wilt and begin fruiting.

By Tina Jepson

Since tomatoes are a fairly fickle plant, about halfway through the summer you may be wondering how to maximize your tomato yield.

But first, let’s consider why your tomato plants aren’t producing the way you want them to. All garden plants can easily be negatively impacted by too much or too little water, inadequate sunlight, pests, unbalanced soil levels, and so on. However, you could provide your tomatoes everything they need and more and still notice a lack of growth.

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What gives? It’s completely possible two things are going wrong:

1. Bees and other pollen-loving insects aren’t coming to your garden, or there hasn’t been enough wind lately, both of which greatly aid the pollination process.

2. You aren’t pruning your plant enough to redistribute its energy

By focusing on these two things, you’ll all but guarantee a thriving garden. Are you ready to maximize your tomato yield this summer? Here’s how!

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Hand Pollination for Beginners

Choosing to hand-pollinate tomatoes is never a hard decision for me. In fact, I always pollinate the first flowers from my tomato plants every year.

Yes, it’s completely true that tomatoes are equipped with both male and female parts within each flower. But if the elements aren’t cooperating and there isn’t ample wind and/or insects, pollination is never a given. Therefore, if you want to guarantee early tomatoes, or if it’s too hot, cold, humid, or rainy, then hand-pollination is the way to go.

To hand-pollinate your tomatoes, you need just three tools:

1. An electric toothbrush

2. Cotton swabs

3. Stellar eyesight

Start by shaking your tomato plant, particularly the small branches with flowers attached. This movement helps to loosen the pollen from the flowers. Then, take your electric toothbrush (I use a battery-powered children’s toothbrush that cost $6) and gently place the vibrating brush directly behind each flower, allowing the flower to move. This will help distribute the pollen within each flower.

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Then, about two or three days later, use a cotton swab or fine-tipped paintbrush and gingerly swirl it inside each flower. This is another great way to move the pollen from the male to female flower parts.

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Alternate these two methods every two or three days for as long as you want, and you’ll help your tomatoes produce quickly and effectively.

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Pruning 101

How can trimming your plant promote growth? Just think about it in terms of energy usage. When an indeterminate tomato plant uses its energy on 15 branches as opposed to 30, that means that more energy, and thus nutrients, are expended on a smaller number of fruits. So, in a way, controlled growth=healthier (possibly larger) fruit. Jackpot!

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Keep in mind that determinate tomato plants grow to a particular height (3-5 feet), produce fruit within a short time period, and then ultimately die off. Because they don’t grow unchecked like indeterminates, you don’t need to prune them.

However, pruning indeterminate tomatoes is highly recommended, and is actually quite simple.

To prune your tomato plants, you only need a pair of pruning shears or utility scissors. Next, find the second-lowest cluster of flowers. Working downwards from this point, use your fingers or the pruning shears/scissors and carefully remove the plant’s suckers.

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What are suckers? Tomato suckers are the growth found between the main stem and a branch. Suckers start out small and leafy but grow into thick branches over time. By taking them off the bottom of your plant, you concentrate the growth toward the top of the plant.

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Once you remove these suckers, give your tomatoes time to grow and thrive. If you notice dead leaves or broken branches, remove them promptly. In a matter of weeks, you’ll begin to notice a stronger main stem and concentrated fruits.

Is there anything better than a warm, red, juicy Brandywine fresh from the vine? I honestly can’t think of anything off the top of my head.

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But it’s up to you to ensure your tomatoes grow to their maximum potential in terms of both size and overall yield, and you can do this through hand-pollination and pruning.

Images used with permission, courtesy of Tina Jepson, www.dreamstime.com, and www..com

Pollination Myths

Gardening myths abound, and we’ve probably all been guilty of perpetuating some of them until we learned better. Although much of garden mythology is benign, misconceptions about pollination can be downright serious, affecting the types of plants we choose to grow or the quality of seeds that we save. With that in mind, it’s prudent to dispel some popular myths about pollination in home gardens once and for all.

Myth 1: Sweet peppers and hot peppers need to be separated in the garden, or you’ll be surprised with hot sweet peppers.

It is true that most varieties of hot and sweet peppers grown in home gardens are the same species, Capsicum annum, and capable of cross-pollinating, but that is the only grain of truth to this common pollination myth. Cross-pollination of almost any fruit or vegetable variety will only affect the NEXT generation of plants grown from the seeds. That means that you won’t know that cross-pollination has occurred until you save seeds from those peppers and grow them out the following year. Why does it only affect the next generation? The flesh of a pepper, like other fruits, doesn’t develop from the fertilized ovules — it develops from the ovary wall that surrounds them. This means that the genetics of the mother plant determine the characteristics of the fruit that is produced, not the genetics of the seed.

Basic flower anatomy (adapted from Wikimedia Commons).

What about the pepper seeds, you ask… shouldn’t they be hot? Capsaicin, the substance which gives peppers their heat, is not produced in the seeds at all, but is abundant in the inner membrane and fleshy interior ribs that support them.

So, basic botany explains how this myth is biologically implausible, but how much should you trust theory? Three summers ago, a friend asked me to start 6 seeds for him of Bhut Jolokia, or “Ghost Pepper” — the hottest pepper in the world at the time. Chris let me keep one of the plants, which I planted in the garden right alongside my other sweet and hot peppers. The Bhut Jolokia was one of the most prolific peppers we grew that year, spreading taller and wider than any of the other plants (over 5 ft high) and producing loads of scary-red peppers. I harvested the Ghost Peppers with gloves and a doubled ziplock bag, but we never tasted any additional heat in any of the other 18 varieties of peppers that I grew that year, including the sweet peppers grown immediately nearby.

Myth 2: Cucumbers and squash should never be planted next to cantaloupes or honeydews, or they will cross-pollinate and you’ll end up with bland-tasting melons.

Although cucumbers, squash, muskmelons, and watermelons are all cucurbits, they are all different species, making it genetically improbable for them to cross-pollinate, with some rare exceptions (primarily among winter squash species). Varieties within the same species can cross-pollinate (e.g., cucumbers with cucumbers), but even then, like peppers, you won’t know it until you grow out the seed the next year. When a melon doesn’t match your expectations for taste, environmental factors are most likely to blame (melons are very sensitive to water and soil fertility), not the 20 zucchini plants in your neighbor’s backyard.

Is there ever a time that cross-pollination matters to the harvest? It does if you are growing corn. Sweet corn grown next to field corn will be starchy and tough, as the genetics of the pollen contribute to the character of the developing kernels (~30%). Why is corn an exception? Basic botany comes to the rescue again. The proper development of corn kernels, like the seeds of other flowering plants including pepper and melons, requires double fertilization — that is, two sperm (carried in the pollen) are required to fertilize an ovule. One of the sperm fertilizes the egg within the ovule, which becomes the plant embryo. The other sperm fuses with other nuclei in the ovule to become the endosperm of the seed, which will develop into a food source for the developing plant. The endosperm makes up the majority of a corn kernel, which is why the genetics of the pollen source matter so much. In contrast, there is very little endosperm in the seeds of other garden plants, which instead put all of their resources into developing the cotyledons (seed leaves).

Myth 3: Tomatoes are self-pollinating, so no special isolation steps are necessary for saving seeds for replanting next year.

There are some elements of truth in this myth. Tomatoes are self-fertile, but they aren’t self-pollinating in the truest sense of the word. If this doesn’t make sense to you, take a closer look at a tomato flower. You won’t find pollen on exterior anthers; instead, the pollen is produced internally and must travel down a hollow stamen and drop onto the stigma. Left on their own, tomatoes don’t set fruit well — motion is required to shake the pollen out. Wind can do it, but bees do it most effectively, which is why greenhouse-grown tomatoes will fail to set fruit unless bees are introduced (or humans agitate the plants). Hurray for pollinators!

Although most of the pollen that reaches the stigma of tomato flowers is from the same plant (similar to peppers), there is still the opportunity for cross-pollination. If you grow several varieties of tomatoes in your garden each year and you want to make sure that your seed is pure for saving, simply exclude the pollinators using caging around the plants, or bags around the flowers. Most seed-savers don’t take such steps, however, as the frequency of cross-pollination is pretty low (1-5%). And if the number of tomato offerings in the Seed Saver’s Exchange Yearbook is any indication, most folks prefer variation in tomatoes anyway.

Myth 4: Since bean flowers self-pollinate before they open, the seeds will always breed true for seed-saving.

Most beans do in fact self-pollinate before they open, and for many varieties of beans cross-pollination is indeed a rare occurrence. Hungry bumblebees can facilitate crossing when they chew through unopened bean flowers to gain access to the nectar, as heirloom bean expert Bill Best explains in his book, “Saving Seeds, Preserving Taste.”

Many varieties of beans, although self-pollinating to a large degree, still require visits from pollinators to set the maximum number of seeds. Lima beans in particular perform better with the services of pollinators, as unlike most bean species, the anther and stigma do not contact one another during flower development. Instead, most of the pollen falls onto the style (which supports the stigma); when a bee pushes it’s head into the flower, the style and stigma are forced out, the style’s pollen is dusted on the petals, and the stigma picks some of it up when it retracts. Although wind may also help lima bean pollen find the stigma, bees more effectively “trip” the flowers and get the pollen where it belongs (or deliver pollen from other bean plants in the process). From my own experience in the garden, I can attest that we saw a major difference in fullness of our lima bean pods after we began beekeeping and attracting native pollinators.

Myth 5: Honeybees are the most important pollinators to the home gardener.

Honeybees are invaluable workers in the home garden, but as much as we love our hives, I would argue that we exalt them at the expense of our native pollinators. If you love to grow squash, bumblebees are far more important. Cowpeas? Invite wasps, a misunderstood garden ally (as explained here). And don’t forget about the thousands of species of native pollinators, such as mason bees, sweat bees, leafcutter bees, and carpenter bees (I see more of these native bees working in my garden than my honeybees, who live in hives placed right at the garden’s edge). Many folks wouldn’t dream of swatting and killing a honeybee, but yet consider these other important pollinators a nuisance. Let’s look out for all of our pollinators, o’kay?

Bumblebees doing all the work pollinating squash blossoms.

I’m currently writing up an article about making your own tomato hybrids, and I’m just going off on a related detour for a moment.
There’s a lot of conflicting information about how readily tomatoes naturally cross-pollinate. Some gardeners swear they never do, while others report getting weird hybrids showing up when they least expect it. I’ve even bought a packet of baby cherry tomatoes from a major seed catalogue and had them grow into beefsteak-style monsters. Tomatoes are essentially inbreeders and have no biological imperative to cross-pollinate, but clearly they sometimes do.
Well, in the last few weeks I’ve spent a lot of time on my hands and knees staring into tomato flowers, and I think I can see how a lot of the confusion arises. Tomato flowers may appear pretty similar … those little yellow cones and star-like petals are much of a muchness. But once you start peering at them closely, and more importantly, taking them apart … you find there’s a heck of a lot of diversity between varieties which potentially affects their pollination habits. And not only does it vary between varieties, it may affect them differently from garden to garden and with the weather and a whole lot of other factors. Which would explain the reams of conflicting information about whether/how tomatoes cross.
Big elongated green sepals are a quirky feature of Tangella flowers, whose buds look like tiny curled stars
Tomato flowers all have the same basic structure. The yellow cone in the centre is made up of anthers which are fused together. In most cases the cone is sealed all round so that insects can’t get in, and the pollen is shed on the inside. Under normal circumstances the pollen falls straight onto the stigma (which is enclosed inside the cone) without ever coming into contact with the outside world. And that’s why tomatoes rarely cross-pollinate.
But … sometimes they can. These are the observations I’ve made on my own plants … pollinator activity varies hugely from garden to garden.
Tangella, as I’ve mentioned before, has oddly structured flowers. The sepals are curled over backwards even in the earliest bud stage, and as the flowers develop the sepals remain hugely longer than the petals. On the inside though, the reproductive bits of the flower are pretty normal and average. It’s a nice easy one to hand-pollinate because the pistil is large and the stigma very obvious when it’s receptive. But the curliness isn’t just in the sepals; the anther cone also curls outwards at the very tip, and that creates a small hole, big enough for a small insect to get inside. So although the pistil is short enough that it remains just inside the cone and may not be reachable by bees, it could theoretically be pollinated by something else.
Clementine has smaller paler flowers than average which grow in unbelievably massive trusses. The anther cones are compact and stay tightly closed, so self-pollination is assured. But … unlike all the other tomatoes I’m growing, Clementine attracts bees. Particularly bumble bees. They don’t get a lot of joy out of it because the flowers are tight shut and I’ve had a few amused moments watching them desperately paddling their legs on the petals trying to get in. But they keep coming back, and if they really want to get at the pollen they may bite their way through the anther cone, which would be the first step towards cross-pollinated tomatoes.
Black Plum produces quite generous amounts of pollen, even in cool weather. It has an anther cone which is fairly open at the end, and a pistil which is long enough that the stigma is flush with the tip of the cone and therefore accessible to pollinating insects. But in my garden the insects don’t go near it. So I would say Black Plum is biologically more geared up for cross-pollinating than most tomatoes, but what with throwing so much of its own pollen around and lacking insect allure I think it’s still most likely to self-pollinate. But in certain circumstances I could see it hybridising like mad.

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