How to Pollinate Plants in a Greenhouse
Now that our tomatoes, melons, snow peas, and cucumbers are blossoming in our greenhouse, I have a burning question: How to pollinate plants in a greenhouse? Tomatoes need pollination, I know, but what other plants do? And in the absence of bees or insects which often do the job, how is it going to happen? We do have some wind, both from the fan we run when the greenhouse gets hot and from wind outside blowing through our window screens. But is it enough?
Clickable Article Contents
- Videos Show You How to Pollinate
- Greenhouse Pollination
- How Often?
- How Will You Know that It’s Working?
- Things to Help with Pollination in a Greenhouse
Videos Show You How to Pollinate
The two very short videos on hand pollinating tomato plants show you two different ways to do it, both easy. Today I used these methods in my greenhouse and I plan to continue, more or less daily.
The pollen from the male blossoms (or male parts of the blossoms) needs to get to the female blossoms (or parts). Some plants, like tomatoes, peppers, eggplants, and other nightshades have both male and female parts on each blossom. I imagine that’s why they are sometimes called self-pollinating.
Without insects, bees, or wind in your greenhouse, you will need to do something. If you tap or shake blossoms, that will do it. People even use an electric toothbrush to vibrate the blossoms. Whatever you do, you are mimicking the effect of the wind or insects.
For plants where the male and female blossoms are a little bit apart, a simple shake may not be enough. As the cucumber video above shows, you can use a paintbrush. Alternatively, you can snap off a male flower, break off the leaves, and rub what’s left on the female flower.
Plants that have separate male and female flowers
- Squash, both summer and winter types, including zuccini
Plants where each flower is both male and female
Veggies and Others that Do Not Need Your Help in Pollination
- Brassicas (broccoli and the like)
- Leafy greens
- Root veggies
- Legumes: peas, beans
You should pollinate tomatoes pretty much every day. It’s best to pollinate any plants in the middle of the day, say experts, but any time the blossoms are open will do.
How Will You Know that It’s Working?
Once you see the fruit growing larger, it has worked
If you see blossoms dropping off the plant and no fruit comes along, it’s not working.
Things to Help with Pollination in a Greenhouse
There are spray bottles of something called Blossom Set, which is a natural hormone you spray on the blossoms. There is a lively discussion in the customer reviews of the first image on the left here, about the efficacy of it. It does not appear that you would want to save seeds from tomatoes or maybe other veggies grown this way, as the discussion mentions. People are happy with the increased yields they often get.
The last two images are of a mechanical pollinator; you could also try a battery-powered or electric toothbrush. The Blossom Set seems to far outsell these devices.
Bonide 543 Ready-to-Use Tom/Blossom Set, 8-OunceTomato & Blossom Set Spray Ready To UseVegiBee Battery Powered Plant PollinatorVegiBee Rechargeable Sonic Plant Pollinator
They might be but I have done pollinating without them, thereby getting around the question!
Wondering if these sprays to help pollinate are chemicals…
I am totally organic.
I wasn’t thinking much about bee die-off in doing this post since my main gardening emphasis right now is in our greenhouse, but your point is well taken, Kathryn. And these methods are quite simple!
My husband and I watch a documentary on television last week about the bee die-off and it showed people hand-pollinating some trees. My French is not very good, so I am not sure what kind of trees they were. They produced a fruit that looked like white cherries. Not sure what that might have been. Anyway, it made me realize that pollination is something we all need to add to our skill sets; because, if things keep going as they are, we may need it.