Do you get flowers but no fruit on plants such as cucumber, squash or tomatoes? Do the flowers or fruit just fall off or rot away? Time to hand pollinate.
But the world is not perfect and sometimes nature needs a helping hand if we want to maximize food crop yields in our smaller urban outdoor spaces.
And who doesn’t want bumper crops of fresh tomatoes, cucumbers, squash and zucchini? Well, maybe not the last one as usually having enough zucchini is not the issue, it’s getting rid of the excess that is!
Natural pollination doesn’t occur perfectly when you grow vegetables in a greenhouse, when it is very hot and the air is still, and when you don’t have enough pollinators helping you out.
So you then have to help your plants out and hand pollinate. This is not difficult, nor time consuming, nor does it require specialized tools or equipment, so it is well within the capabilities of even beginner gardeners.
Why hand pollinate?
Usually we think of bees as being the main pollinators. When you see bees buzzing from flower to flower, they are collecting nectar to make honey. Bees’ bodies are fuzzy so pollen from the flower sticks to them easily. As they visit from flower to flower the pollen transfers from the male to female flowers and pollination happens from contact with the stamen (male) and stigma (female).
There are other pollinators such as butterflies and birds and pollination works similarly as these pollinators visit from flower to flower.
There are many ways to attract pollinators to your garden, but that is for a future article.
Even just the wind blowing through your garden will help to disperse pollen when the flowers are open.
But there are a lot of factors that can affect how well pollinators can do their job. Bees are in decline world-wide, our use of pesticides has affected butterfly populations and wind is not a very reliable pollinator as it leaves a lot of chance.
And if you grow fruiting vegetables in a greenhouse, there is no guarantee that pollinators will enter and buzz around. And there is no wind to disperse the pollen either, unless you have really strong ventilation fans.
If pollination doesn’t happen, then usually the fruit under the female flower will yellow and rot or wither away as you can see here on my kabocha squash vine. This could happen on just a few fruit or all of them if conditions are not right.
On certain plants the blossom will simply fall off taking with it the fruit or the fruit will simply not develop at all.
So you’ll have to help nature out a bit by acting like a bee (no, it doesn’t involve wearing a bee costume!) or the wind (blowing sounds optional).Help nature out a bit by acting like a bee (no, it doesn't involve wearing a bee costume!) or the wind (blowing sounds optional): hand pollinate your fruiting plants #handpollinate #betterharvest #fruitset
What to hand pollinate
The plants that usually need some help with pollination are the fruiting plants.
What are fruiting plants?
By fruiting, I mean plants that produce some kind of hanging “fruit”. Some examples are cucumbers, eggplants, melons, peppers, pumpkin, squash and tomatoes. These all rely on pollination to set fruit.
Some of these fruiting plants have both male and female flowers, which means pollen has to be able to travel from a male flower to a female flower for pollination to happen. Cucumbers, melons and squash (including pumpkin and zucchini) are called monoecious plants as they have both types of flowers on one plant.
A female flower is easy to spot, as usually it will have a small nodule or fruit just underneath the flower. [image here] The male flowers on the other hand are on plain stems. Usually a plant will produce adequate numbers of female and male flowers, sometimes heavier on the male side as this ensures more pollen to impregnate the female flowers.
Perfect flowers on the other hand are self-pollinating. So eggplants, tomatoes and peppers fall into this category. The male and female parts are all in the same flower so in theory these should not need hand pollinating. But even these flowers can use some help to increase yields.
The only tool you’ll need is a small paintbrush or cotton swabs. Make sure they are clean and dry.
A clean cloth to wipe the paintbrush is also a good idea if you are moving between two different plants. This is mainly to avoid spreading any diseases but could also prevent cross-pollination if you are planning on saving seeds for next year.
If using cotton swabs, simply use a new swab or switch ends on double-ended swabs when you move between plants.
For monoecious plants (with a male and female flower) you will have to wait until the plant has both. You can’t pollinate if there are no female flowers to pollinate or male flowers to get pollen from. Check your plants daily to catch this as it can happen fast.
Early morning is the best time to hand pollinate. Squash flowers usually only last one day so you’ll want to catch them early before the heat of the day hastens their demise. You can easily do this before going to work for instance, as it only takes a few minutes. Don’t worry if the flowers are not yet open, so long as they have formed.
For perfect flowers timing is more related to time of day as you don’t need both male and female flowers (all flowers have both stamen and stigma). You can hand pollinate from morning to early afternoon but before noon seems to be the best before it gets too hot. Humidity makes pollen very sticky so if your region’s early mornings are blessed as being fresh, again stick with mornings. In some regions in summer there never is a time during the day when it is not humid so pick when it is coolest (again probably early morning).
Experiment with different times to see if it makes a difference for your region or talk to someone else who hand pollinates to find out when they do it.
Let’s hand pollinate
I’ve split this up into the two different flower types as the technique for each is quite different.
Monoecious plants (male and female flowers)
There are two methods here. For the larger monoecious flowers such as squash you can use the actual male flower as the paintbrush.
Remove a male flower from the plant. Pick one that is relatively new and fresh. It doesn’t have to be open. Remove all of the petals so that you expose the stamen which should have a decent coating of pollen (a yellow dust).
Now find a female flower (again the newer or fresher the better) and open it up. It’s okay if you tear the petals as the petals are mainly there to attract pollinators with their bright colour.
Now jab the male flower into the female flower moving it around so that the pollen rubs off on the female flower’s stigma. That’s all there is to it.
You might be able to use the male flower again on another female if there still is enough pollen on it. Usually though you’ll have enough male flowers.
The second method is where the paint brush or cotton swabs come into play. And this works best on the smaller blossoms such as cucumbers and melons. The photos show melon blossoms.
Simple take your brush or swab and go to one of the male flowers. Again this is a flower that doesn’t have a swollen nodule just under the blossom. Stick the brush/swab in and rotate it a few times to get a good coating of pollen on it. You may have to open the flower slightly when removing the brush/swab to avoid scraping the pollen off again.
Now move to a female flower, one that has a nodule or baby fruit just underneath the flower. You can see the elongated melon baby just above the yellow blossom in the photo below. Stab the brush/swab into it and again move it around.
Repeat the gathering of pollen from a male flower and depositing it into a female flower as needed. When moving to another plant, remember to clean your paintbrush or use the other end or a new swab.
Perfect flowers (male/female in one flower)
These are much easier to pollinate and in most cases actually don’t need any help pollinating, especially outdoors. If you have tomatoes, peppers and eggplant in a greenhouse though, they don’t usually have a breeze that moves the flowers enough so that the pollen has a chance to move from stamen to stigma in the same flower.
Again there are two ways to help these flowers get pollinated.
First one is to use the paintbrush or swab as you did above on the smaller blossoms. However this time all you need to do is move the brush/swab around inside each flower, not bothering to move pollen from flower to flower (although that can’t hurt).
The other way is to shake the blossoms. Do this gently by shaking the fruit trusses enough to move pollen around inside the flowers. Or you can also try vibrating the blossoms with an electric toothbrush. There are even commercial pollen shakers (expensive) or try using something you find in the bedroom that vibrates 😁.
So in just a few minutes of your time every day or every few days, you can make a huge impact on how successful your fruiting plants will pollinate. Grab that paintbrush and hand pollinate your plants to give them a better chance!In just a few minutes of your time every day or every few days, you can make a huge impact on how successful your fruiting plants will pollinate. Grab that paintbrush and hand pollinate! #handpollinate #betterharvest #fruitset
Good luck with hand pollinating and hope you get a great harvest. Let me know in the comments if you see a big difference.
If you enjoyed this article, have something to add or have any questions, please leave a comment below.
Wishing you all the best!
Tranquil Urban Homestead, Victoria, BC