How (and when) to Lend a Helping Hand

pollinating bee

Birds do it! Bees do it!
And yes, your hydroponic tomatoes do it too

We're talking about fertilization here... reproduction... the transfer of pollen from the male to female parts of the plant so flowering and fruiting can result.

Outdoors, crops are naturally and easily pollinated by bees and the wind. But indoor gardens (greenhouses and hydroponics) sometimes need a little help to complete the plant pollination process.

   No Problem!

The plant pollination process...

The good news is: there really are few vegetables that need to be pollinated by hand. Let's keep this simple!

You can break your veggies down into three different groups:

1. Leaf and root crops: Pollination is not important at all for these, so don't worry about it:
(leafy greens, spinach, cabbage, herbs) and roots (beets, carrots, radishes)

2. Self-pollinating: Each flower contains all the necessary parts to make a fruit; hand pollination is almost never necessary for this group:
(tomatoes, peppers, eggplants, all beans and peas, greenhouse variety cucumbers)

3. Cross pollinating: These plants sprout male and female flowers, which are different. The male flower will have pollen-laden stamens and the female flower will usually have what looks like the tiny bud of a vegetable at the base.

Cross pollinators usually need a hand or artificial pollination if they are not grown outdoors.
(melons, squash, most cucumbers)

 When To Pollinate

If you follow our advice to always keep an oscillating fan gently circulating air in your garden, chances are, pollination will take place without any help at all.

When your fruiting crops sprout flowers, and the petals curl back, it is time for you to lend a hand. You want to do the pollen transfer every other day for 4-6 days. Do this at midday, when the humidity is lowest.

This increases chances of success with a plant pollination process.

   How to hand pollinate

There are two ways you can artificially pollinate your crops:

1. For self-pollinators, you usually don't need to help, but if they just don't want to set fruit, you will need to do one of these to lend a hand:

  • Gently flick the stems near the flowers with your finger.
  • Hold an electric toothbrush on the stem near the flowers for a few seconds.
  • Brush inside each flower, making sure the pollen gets down into the pistil (middle part) of the flower.

2. For cross-pollinators, you will have to transfer pollen from the male flowers to the female, by hand.

  • Get a cheap, small watercolor brush, or use a q-tip. The male is just an ordinary flower. The female flower is on the end of a tiny squash or cuke, you have to look carefully. Brush up some of the pollen from the male flower and transfer it to the pistil on a female flower.
hand pollination

Amazing! You are now a practicing botanist. And what a great lesson in nature for the kids! (Hydroponics makes a super science fair project).

   Still no fruit?

If your plant still doesn't set fruit in a few days, (tiny fruits either do not appear or they shrivel and dry up) then something else might be wrong. Stress can cause your plants to conserve energy and forget about bearing fruit.

What kind of stress? Inadequate moisture, lack of light, and nutrient deficiencies can cause fruit-drop. Another common cause is a mid-summer heat wave. High day and night-time temperatures will stress the plant, and the fruit may abort as a result.

Don't panic! If you cool off the grow room, you will see new females appear and successful pollination should then occur.

tiny cucumbers on female flowers

See the tiny cukes under the flowers?


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