Green beans are a satisfying vegetable to grow yourself. Not only do they produce prolifically once established, but green beans are also a largely self-sufficient plant when it comes to pollination and fertilization.
Understanding how bean flowers pollinate and set fruit can help you troubleshoot any issues with low yields. Read on to learn all about green bean flower anatomy, pollination and how to support successful fruit set.
Parts of a Green Bean Flower
Green bean plants produce flowers that contain both male and female reproductive parts within each blossom. This makes green beans self-fertile.
The anatomy of a typical green bean flower includes:
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Petals – Usually white in color, the petals attract pollinators to the flower.
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Stamens – These thin stalks inside the flower contain the male pollen sacs or anthers.
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Pistil – Consisting of the stigma, style, and ovary, this female part of the flower contains ovules that, once fertilized, become seeds.
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Keel – Two fused petals form a keel that encloses and protects the reproductive parts.
How Green Bean Flowers Pollinate
With both male and female parts within each flower, green beans mostly self-pollinate. This means pollen from the stamens can directly fertilize the same flower’s ovules without any outside help.
Here is the basic sequence of green bean flower pollination:
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Pollen sacs on the stamen dehisce (rupture) and release pollen grains into the flower. This often happens before the flower has fully opened.
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The pollen grains land on the flower’s stigma.
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The pollen then travels down the style to the ovary.
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Once inside the ovary, the pollen fertilizes the ovules.
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After fertilization, the ovary starts to develop into a green bean pod containing the seeds.
This entire fertilization process takes place autonomously in most green bean varieties without any insect pollinators. Though bees and other pollinators do visit the flowers, they are not necessary for fruit production.
Occasional Cross-Pollination
While green beans mostly self-pollinate, cross-pollination between different flowers on the same plant or neighboring plants can occasionally occur.
This cross-pollination happens when:
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Pollen gets moved between flowers by wind or insects.
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The keel petals fail to enclose the reproductive parts, allowing pollen to escape.
If you are saving green bean seeds, cross-pollination could affect the traits of the next generation. But for eating beans each season, some natural cross-pollination is not an issue.
Troubleshooting Poor Pollination
Though green beans are well-equipped to self-pollinate, you may encounter issues like:
- Flowers dropping off without forming pods
- Low yields
- Lack of seed formation inside pods
Before blaming pollination, rule out other potential causes like:
- Extreme temperatures
- Dry soil
- Insufficient sunlight
- Poor nutrition
- Pest damage
Assuming none of these are factors, here are some ways to improve green bean pollination and fruit set:
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Plant closely together – Having plants clustered together helps move pollen between blossoms.
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Attract pollinators – While not essential, visits from bees and other insects can facilitate pollen transfer. Have pollinator-friendly flowers nearby.
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Adjust watering – Too much or too little moisture when flowers are forming can impact pollination.
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Try shaking plants – Gently shaking plants on a dry day can promote pollen shed and increase pod set.
Ideal Conditions for Pollination
You can support successful green bean fertilization by providing ideal growing conditions:
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Full sun – Beans thrive in at least 6 hours of direct sunlight per day. Insufficient light discourages flowering.
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Consistent moisture – Water beans regularly so soil stays evenly moist but not waterlogged. Drought stress during flowering inhibits pollination.
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Moderate temperatures – Daytime temps of 70-85°F and nights above 50°F are best during flowering and fruiting.
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Good air circulation – Avoid dense plantings and promote air movement to prevent fungus issues on flowers.
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Low humidity – Excessively damp conditions can make it harder for pollen to shed and move between flowers.
Common Bean Flower Types
While most green beans contain perfect flowers capable of self-pollination, some other bean types have different bloom structures:
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Runner beans – These have perfect flowers that also self-pollinate well.
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Fava beans – Flowers contain only female parts, so rely fully on insect pollination.
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Lima beans – Varieties have either perfect flowers that self-pollinate or male and female flowers requiring cross-pollination by bees.
Squashes, melons and monoecious cucumbers
can easily be hand pollinated. Cukes are notorious for needing help being fertilized! Cucurbits have male and female blooms on the same plant. If there are not enough pollinators about, we need to help. Also, multiple visits from the bees are required for good fruit set and properly shaped cucumbers. Male flowers open in the morning and pollen is only viable during that day. Hand pollinate during the morning hours, using only freshly opened flowers. You can move pollen from the male stamen to the center of the female flower with your finger, a small paint brush with a point, or a cotton swab. Take the male flower off the plant, pull off the petals, and carefully roll the male flower anther around and over the female stigma in the middle of the female flower. This is the best and most complete way to do it. The pollen is sticky, so it may take some time. One male anther can pollinate several females. Repeat. Female blooms will simply drop off the plant if they are not pollinated. So when your cukes are in production, you need to do this daily.
Don’t be confused by the little fruit forming under the female flowers and think pollination has already happened. The flower needs to be fertilized, and adequately, or the flower and fruit just fall off. Flowers not pollinated enough, that don’t abort, make misshapen fruits. That goes for corn having irregular to lacking kernels. Misshapen Strawberries are called cat-faced. Squash and cucumbers can be deformed. If it’s not windy, tilt the stalk so the corn tassels are over the silks and tap it. You will see a shower of pollen fall on the silks. You might have to move from one plant to another to avoid breaking the stalk while trying to get the pollen to land on silks on the same plant.
Planting a lot of plants close together stresses plants. Plants compete for water, food, and sunlight when they are crowded together. This stress can cause more male flowers and fewer female flowers, which are the ones that make fruit. If you really want more fruit, give them room to be fruitful. The same is true for other stresses, like damage from bugs or wind-blown soil, low light levels, or not having enough water. Less female flowers are made when these things happen.
Weather affects pollination. Sometimes cool overcast days or rain, when bees don’t fly, there is no pollination. Rain washes pollen away. High humidity makes pollen sticky and it won’t fall. Drought is a problem for corn pollination. Your tomatoes, cucumbers, and other vegetables won’t be able to make pollen or set fruit if the temperatures are too high at night (86°F or higher) or during the day. Too windy and the pollen is blown away.
If it is your cucumbers that are not pollinating well each year, try parthenocarpic varieties. Parthenocarpic varieties produce only female flowers and do not need pollination to produce fruit. This type of cucumber is also seedless. Try a few varieties and see if you like them.
The most important thing you can do is plant flowers for every season in your area. Make sure the flowers are close to or right next to your plants so that wild bees can live there. According to Cornell, native bees are two to three times more effective than honeybees! If the weather is bad or something else stressful happens, you can hand-pollinate the flowers.
May your Veggie Basket be overflowing!
The Green Bean Connection newsletter started as correspondence for the Santa Barbara CA USA, Pilgrim Terrace Community Garden. All three of Santa Barbara city community gardens are very coastal. Most years, we live in an area with a marine layer or fog belt in late spring and summer. This area is known locally as the May grays, June glooms, and August fogusts. Keep that in mind compared to the microclimate niche where your veggie garden is.
Love your mom! Plant a bird.
Urban Farmer Newsletter for Coastal Southern California, Santa Barbara CA Community Gardens
June 7, 2019 by Cerena Childress
In optimal conditions insects, mainly bees, pollinate our veggies. Wind works for some plants. Other times due to weather or stresses, humans help!.
The beating of bumblebees’ and other insects’ wings at just the right frequency fertilizes plants like tomatoes, peppers, and eggplant. This is because more pollen is released, and pollination works better. There’s a way to make your tomato, eggplant, and pepper plants grow better: give the cages they’re in or the main stems of your plants a few sharp taps or gentle shakes around 11 a.m., that’s when the male flower anthers (which hold the pollen) are most open. This will help the flowers self-pollinate. Or hand pollinate using a small paintbrush or cotton swab. In the greenhouse you can help these veggies simply by adding a fan to move the pollen.
To attract native bees, build condos for them to live in alone. Honey bees don’t pollinate tomatoes, peppers, potatoes, eggplant, blueberries, or other Solanaceae. Bryan Danforth, an entomology professor at Cornell, says that native bees are two to three times better at pollination than honeybees. They are also more common than was thought before and not as likely to suffer from colony collapse disorder, which has wiped out honeybee populations. A study from January 2019 in the UK found that strawberries are bigger when pollinated by wild bees than when pollinated by honey bees. This is why they say it’s worth it to make space for them!
The very best Solanaceae pollinator is a Bumblebee!!! See more! Bumblebees fly earlier in spring and bring in our first spring crops! And they don’t sting!
Video Produced by Joshua Cassidy
Please click on the or here to see the video!
And, did you know Flowers can hear buzzing bees—and it makes their nectar sweeter!
If your tomatoes are grown in cages, very gently help them up through the cages while you help them pollinate. Remove any bottom leaves that might touch the ground when weighted with water. Remove any diseased leaves ASAP!.
Pollination of Cucurbits by hand. In left , male flower on left, female right.
Do I need to pollinate Bush Beans?| Self pollinating | Fertilizer for Bush Beans
FAQ
Are green beans self-pollinating?
Why are my green beans flowering but no beans?
What vegetables are self-pollinating?
Can I plant different types of beans together?
Are green beans self pollinating?
Green beans are self-pollinating, meaning they do not rely on insects or wind to transfer pollen from the stamen to the stigma. However, sometimes self-pollination can be inefficient, resulting in poor yields. Hand pollination can help increase the success rate of pollination and thereby increase your yield.
Can one survive on beans alone?
It is not possible to live eating only one food. The human body needs nutrients that are not present in beans, therefore, if someone consumes only beans to survive, they will suffer consequences such as nutritional deficiency that will trigger problems and diseases that can and will certainly lead to death over time.
Should you hand pollinate green beans?
However, sometimes self-pollination can be inefficient, resulting in poor yields. Hand pollination can help increase the success rate of pollination and thereby increase your yield. Hand pollinating green beans is a simple process that can be done in just a few minutes.
Do green beans need pollinators?
If you don’t, go ahead and water. Green beans have complete flowers (with both male and female parts) and are considered self-pollinators. This means they don’t require pollinators, like insects, to produce pods. If you’re growing a balcony garden, this is definitely a bonus!