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How to Prevent Cross-Pollination (Complete Guide)

The easiest way to prevent cross-pollination is by growing only one variety of each kind of plant (such as one kind of squash or one kind of tomato). 

You can also keep your plants in a greenhouse to reduce the risk of pollinating insects carrying pollen to your plants from other flowers nearby.

Cross-pollination is usually only an issue for people who grow their own food and wish to save the seeds from their current plants to produce the next year’s crop. 

If you want to do this and your plant gets cross-pollinated, you may find that your vegetables lose some of their more desirable traits or even become inedible.

Thus, you want to avoid cross-pollination if possible. 

How Does Cross-Pollination Happen?

Most plants become pollinated by the wind or by insects that carry pollen from flower to flower as they drink the nectar the plants offer.

Or, sometimes, animals pollinate plants, specifically rodents.

But, plants always need pollen to arrive from another flower so they can become fertilized and grow fruits and produce seeds.

However, if the other flower is not quite the same variety, the pollen from the two plants will mix and form a hybrid plant in its seeds.

Therefore, your seeds won’t have the same genetic makeup as the two parent plants.

Plus, unwanted cross-pollination can result in vegetables that are inedible, or just weaker, less desirable plants than their parents. 

Cross-pollinated vegetables are often not as good because farmers have bred the parent plants to maximize their fruiting, resistance to diseases, and growth speed.

Thus, you don’t want your vegetables to get cross-pollinated unless you are going to buy new seeds commercially next year.

Overall, you should know that vegetables that can easily succumb to cross-pollination include:

  • Squashes
  • Broccoli
  • Cucumbers
  • Melons
  • Cabbages
  • Turnips
  • Spinach
  • Carrots
  • Onions

Read Also >> Hybrid vs. Heirloom Plants

How Can You Prevent Cross-Pollination?

You can usually prevent cross-pollination by keeping your plants away from others that could pollinate them.

And, for the most part, only other plants in a plant’s family can pollinate it. 

For example, squashes can only pollinate other squashes, and beans can only pollinate other beans.

So, if you grow just one kind of each plant, the chances of cross-pollination are low because there are unlikely to be other plants close enough to cause problems.

Even if insects are carrying pollen or if the wind is strong, it is unlikely to arrive from another garden unless your space is small and you are unlucky.

In general, growing just one kind of plant from each family will be enough to prevent cross-pollination.

Growing your plants in a greenhouse or a cold frame will also reduce the risks of cross-pollination, provided you only grow one kind from each family in the enclosed space.

The enclosure will make it less likely that wind and insects will access the plants. 

But you will need to hand-pollinate your flowers using a paintbrush because there will be no bees to pollinate them. 

And without fertile flowers, your plants will not produce fruits or seeds for you to harvest to grow next year. 

So make sure that pollination does occur, even if you have to pollinate the plants yourself.

Read Also >> Why Save Seeds?

What if I Want to Grow More Than One Plant Within a Family?

If you are going to grow multiple kinds of plants within one family, you can prevent cross-pollination by spacing them out. 

However, your plants will need to be over 100 yards apart, and most people don’t have enough space to accomplish this task.

You can prevent cross-pollination in small spaces by pollinating a flower yourself and then preventing further pollination.

To perform this technique, you should select a healthy flower from which you will later gather seeds.

Then, take a paintbrush and collect pollen from another plant of the same variety.

Next, use this paintbrush to pollinate the flower you will collect seeds from, and then tie a paper or cloth bag over the flower.

These steps will prevent other pollen from entering the flower and will allow it to develop as normal since it’s using pollen only from its own species.

When you then collect the seeds from that flower, they should be true to the plant because you have ensured they pollinate correctly.

You can perform this method with as many flowers as you want, but just make sure you use a breathable bag.

A plastic bag will make the flowers too hot and stop the seeds from developing properly. 

So, use a paper or cloth bag at all times.

Read Also >> How to Harvest and Store Seeds?


You can prevent cross-pollination by making it more difficult for pollen from compatible but different plants to reach the flowers of your plants. 

Consider using a paper bag and tying off certain flowers, so you know which ones you can harvest seeds from at the end of the season.

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