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How To Pollinate Plants in a Greenhouse

Bumblebee on a pink flower and the text: Greenhouse Pollination - A How-To Guide

Table of Contents

You love the fact that you outsmart the seasons and grow your beautiful plants any time of the year in a controlled environment. With a greenhouse, you don’t have to worry about pests and diseases, your plants would turn out perfect in your greenhouse.

Your greenhouse is a really great idea, but you’ll need to put up with low yields since you’ve shut the door on nature and the insects can’t help you with pollination any more.

Will you quit your beautiful greenhouse dream, or simply read this and start getting those plants pollinated for maximum yield? Are you a passionate greenhouse gardener hoping to get the best off your plants but your plants don’t just bear fruits? We’ve got you covered.

Here you’ll find something that’ll be beneficial to your greenhouse plants. Guess what? You can perfectly overcome the challenges of planting indoors and get amazing plant yields. I know you really want this, keep reading!

First, what’s pollination?

Pollination is a vital process that plants use to make babies! So, it’s quite literally the reproduction of plants. How, you ask? Birds, insects, bats, and the wind help to exchange pollen grains between flowers.

Pollination is essential for flowering plants to produce any type of seeds and fruits. The exchange of pollen between flowers has the objective of reproduction, which is a fundamental process for the maintenance of life on earth.

People grow some plants for the seeds, e.g. oilseeds, nuts, legumes (such as beans and peas), and basic grains, such as rice and wheat. Other crops produce fruits that develop with the seed, for example, citrus, mango, and tomato.

Seeds are needed for the production of new crops and to improve their quality from plant selection programs.

However, there are some plants that don’t need to undergo these processes.

Bees on blossoms and the text: Pollination Tips - How to pollinate your plants in a greenhouse

What plants do NOT need pollination?

Some plants aren’t just concerned with producing seeds, so they don’t need the process of pollination. Green leaves and roots do not need the process of pollination.

Plants like root vegetables, growing greens, and decorative plants do not need pollination. No need for concerns here!

  • Lettuce, kale, and other leafy greens
  • Cabbage
  • Broccoli
  • Cauliflower
  • Brussel sprouts
  • Onion
  • Garlic
  • Potato & sweet potato
  • Beet
  • Turnip
  • Yam
  • Parsnips
  • Raddish
  • Kohlrabi
  • Celery root
  • Ginger and turmeric
  • Some herbs like rosemary and basil

So, what plants need pollination?

Plants that produce fruits and seeds badly need pollination, they need a process to exchange pollen grains. Now, pollination ensures that flowering plants yield fruits. This in return means, you can produce seeds for growing more plants.

We’ll give you some plant names later.

Bee pollinating a flower in nature

How does pollination occur in nature?

Nature is beautiful, flowers get to have male and female parts. The stamen is the male part of a flower, then the stigma is the female part. While we get to see the long slender stamen with pollen at the end, the stigma lies at the end of the tube, you’ll have to look hard to see it.

Parts of a flower with their scientific names

Did I tell you that the stigma has an ovule too! Yes, it does, the ovule contains eggs too. Never mind, they actually grow into seeds once they are fertilized by the pollen on the stamen. Amazing right?

Pollination is what gets the pollen from the stamen to the stigma. Flowering plants need a procedure to make fruits for you! Luckily, mother nature offers different means for pollination to occur.

What is self-pollination?

Self-pollination is a form of reproduction that can occur in some plant species, the flowers of which often have stamens. This means that self-pollinating plants contain both male and female reproductive parts and can pollinate themselves.

These plants get pollinated when their pollen grains find their way into the ovule. Did I hear you say they are the perfect flowers?  Truly, they are perfect but these plants need just a little help from nature to get pollinated.

The pollen grains on the anther of the flower need to fall into the stigma of the same flower in order to get pollinated. You can easily help the self-pollinating blossoms by tapping or vibrating them. A healthy airflow in the greenhouse may already provide enough movement.

Which plants self-pollinate?

A lot of the common garden plants are actually self-fruitful. This makes it easy for greenhouse gardening.

These plants could use a gentle tap to get the pollination going:

  • Tomatoes
  • Peppers
  • Eggplants
  • Peaches
  • Apricot
  • Sour cherries
  • Currants
  • Grape
  • Citrus trees (but cross-pollination will result in larger yield)
  • Barley
  • Peas
  • Okra
  • Sunflowers
  • Orchids

These plants need a little more – wind or pollinators:

White Strawberry blossom on a plant
Strawberry blossom

Some other self-pollinating plants do not require any help pollinating inside a greenhouse.

Now, how does cross-pollination work?

We get to see cross-pollinating plants more, these plants need pollen grains from another similar plant to get pollinated.

You know the pollens have got to move to the ovule of the stigma if we really wanted to see fruits. How does nature make them move?

We’ve got the bees that love flowers so much. Those tiny flying bees don’t just stay off of beautiful flowers. They collect nectar and pollen from the stamen and move on to make honey.

Guess what happens to the pollen that the flying bee collected? It rubs off on the stigma when the bee visits another flower to get more nectar. Interesting, right?!

This is how the adventurous bees get plants pollinated. Bees aren’t the only ones who help with this, though. Other insects, bats, rabbits, monkeys, and birds that stick around your flowers are really beneficial too. These animals transfer pollen grains using their fur or hairy body parts.

Bee pollinating the flower of a blueberry plant
Blueberry blossoms & developing fruits

Which cross-pollinating plants need pollinators?

  • Blueberries
  • Blackberries
  • Watermelon
  • Squash
  • Pumpkins
  • Cucumbers
  • Apples
  • Pears
  • Plums
  • Sweet cherries
  • Grapes
  • Mulberry

But this is not always the case in a greenhouse?

I know you love your greenhouse plants. The controlled environment and protection from pests give you peace of mind. You want to make the best fruits but your flowers just fall off and nothing happens. This is a sign of missing pollination in your greenhouse.

Inside a greenhouse, we will obtain artificial conditions (microclimate) that ensures higher productivity for the plants at a minimum cost and in less time.

It protects the plants or crops inside it from environmental damage such as frost, strong winds, hail, insect pests …

Therefore we can grow in a greenhouse at any time of the year and they will be much more productive.

But it could get frustrating when you start having challenges with pollination and your plants just won’t bear fruits. Your greenhouse protects your plants from nature, so mother nature hasn’t got you covered on this one. You must do something to help them get pollinated.

Bee pollinating a flower on a tree
Pollination in nature

How can you help them? How do you pollinate in a greenhouse?

Knowing about pollination already helps with determining what plants need help. You can use manual pollination methods, bring in beneficial insects, or use a device.

Create a healthy airflow

The first thing you should ensure is airflow. It’s not only crucial for self-pollinating plants. Airflow also keeps your plants healthy. It prevents mold and other diseases from developing.

So, make sure you have vents and/or doors (preferably barn-style doors) that will create a good air circulation.

Manual pollination

Manual pollination can replace the natural method in a greenhouse. But it requires your time and effort. On a small scale (small greenhouse or few plants that need help), it shouldn’t be a big hassle though.

Alright, you could be a cool gardener that loves to be the hero of the green world. Are you wondering how you would get the task done? Not to worry, you’ll find that here.

To pollinate manually, you simply need to move pollen grains from the male part of the flower to the female part of the flower on a self-pollinating plant, such as tomatoes.

Of course, you’ll have to move pollen from the male part of the flower to the female part of a different flower in a cross-pollinating plant.

You can do this with a little soft brush and plate. Gently touch the blossom while holding the plate underneath in order to catch all the pollen. You could also use the back of an electric toothbrush to imitate the vibrations of an insect.

This method can take some time if you have plenty of plants that need to be pollinated. You are a true hero if you want to give it a try.

Nevertheless, manual pollination is very useful to speed up the fruiting process, especially on cucurbits (melon, watermelon, cucumber, squash …). It is necessary in the greenhouse, on the veranda or indoors, where pollinating insects are rarer, so it replaces natural pollination. 

Give bumblebees a try

If you really don’t want to spend time doing pollinating manually, give bumblebees a try. I tell you, they are reliable and you get to save time with them. They can get your plants pollinated just as you like it. Still, wondering how these diligent creatures can save your greenhouse plants? Let me tell you a quick story.

Amazing bumblebee gets to your greenhouse and grasps a flower. Immediately, your flower vibrates in response, bumblebee quickly collects the pollen…And then, it transfers into the pistil and your plant gets pollinated.

Bumblebee is really generous, it helps a lot of plants get pollinated. It especially pollinates small fruits like black and red currant, blueberry, raspberry, etc.

If you’ve got plants like tomato, kiwi, and eggplant, bumblebees could be your best bet. Bumblebees have large sizes that make them adapted for the pollination of the flowers of some plants, such as strawberries and blueberries. What happens with the tiny flowers?

Bumblebee pollinating a pink flower
Bumblebee at work

Alfalfa Leafcutter bee comes to the rescue

You can call them “the Garden Bee.” The alfalfa leafcutter bee is a very efficient pollinator. They are small and can come in handy with tiny blossoms. They can visit tiny flowers that bumblebees can’t pollinate. The bumblebees are quite large in size.

Leafcutter bees don’t pose any trouble around your greenhouse. They are mild and non-aggressive. They can be a good partner in pollination.

However, you might have to say goodbye to your beautiful leaves. Like their name “leafcutter” signals, they actually cut leaves to fill their tube. Another downturn, they are almost only out in warm summer. But they effectively pollinate melons, cucumbers, and squash.

Alfalfa Leafcutter bee on a plant
Alfalfa Leafcutter Bee (Source: Flickr)

Let’s check out device pollination

You don’t have to put up with bees if you don’t like them! Cool devices can help you overcome low crop yields indoors, without having to deal with the effect of shrinking bees. It’s the easiest method of greenhouse pollination.

You’ve got to be careful when choosing devices for greenhouse pollination. There are a lot of devices out there. Some cause really bad damage to flowers.

The devices are designed to make pollination a really easy task for you. It works by spreading pollen to other areas of the flower to ensure pollination.

Before using these pollinating devices, it’s important that you find out if the plant is self-pollinating or cross-pollinating.

If you are considering device pollination as your ideal solution,  VegiBee Garden Pollinator is a great option.

Extracting Pollen using VegiBee Garden Rechargeable Pollinator
VegiBee at work

This device pollinator imitates the high-frequency vibration created by the bee’s wings during pollination. In fact, it creates 29,000 to 44,000 sonic vibrations just in a minute.

VegiBee Garden Pollinator is great for peppers, beans, peas, eggplants, strawberries, and tomatoes. Do you want a magic touch for your greenhouse plants?

You see, your greenhouse plants only need a little more of your time and effort to get you the best fruits. Greenhouse pollination can be a lot easier with these methods.

Have you tried any of these methods or can you add one? Tell us about your challenges or triumphs in the comments!
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