Use Caging to Prevent Cross-Pollination Between Vegetables

Growing open-pollinated varieties in the home vegetable garden is becoming more popular every year. One of the reasons open-pollinated and heirloom vegetables are so desirable is that the seeds can be saved from year to year with the assurance that the plants will breed true to the original parent plant. This is possible only if the variety you’d like to keep seed from doesn’t cross-pollinate with another variety.

Of course, you’ll still get vegetables, but if the varieties cross-pollinate you can’t be sure what the new plants will produce. For gardeners interested in keeping seeds from their open-pollinated varieties, caging is one of the best ways to keep the seeds they produce pure. Other techniques include bagging and hand-pollinating.

Use Caging for Self-Pollinating Vegetable Plants

Caging is a technique widely practiced by seed-savers everywhere and is an effective physical barrier. For self-pollinating plants, it’s quite perfect as far as pure pollination goes. Although vegetables like tomatoes are referred to as “self-pollinating”, it’s quite possible for insects to interfere by spreading the pollen from other tomato varieties around.

The rectangular or square cage is made from a frame of wood or lightweight plastic. Then, window screen or cloth is stretched over the frame. The screen or cloth must be long enough so that about a foot of it can be buried into the ground. This is to prevent penetration by determined insects and ground-dwelling bees.

You can set the cage over veggies such as peppers or tomatoes when you see flowers. The plants have the opportunity to pollinate themselves without interference from insects that cross-pollinate the varieties.

Use Caging For Insect-Pollinated Vegetable Plants

The cage can be placed over insect-pollinating vegetables, as well. You can use the cages in a couple of ways when working with these types of vegetable plants. The first way is to alternate which plant is caged on which day.

Say you have kale and cauliflower from which you’d like to save seed. These vegetables readily cross-pollinate. So, when the blossoms are visible on the kale, cover it with the cage from morning until night.Remember that ideally, you’d like to cover several of these plants. The cauliflower can then have all the bees’ attention and become pollinated. The next day (early) remove the cage from the kale and place it over the cauliflower plants.

Now the kale has a chance to become pollinated, and the cauliflower remains isolated. This routine continues up to the point where the plants have stopped flowering. To ensure seed purity, it’s a good idea to now cage both types of plants until the seeds have begun to dry.

If a bare cage is used with netting or cloth over the top, be sure that the material is long enough to have rocks or boards hold the ends down. Once again, this will make it hard for insects to get inside. It’s important to note that caging may reduce the amount of fruit that’s produced. Yet, another method is to cage and introduce the necessary pollinators to live in the cage. This is done, quite often, to prevent carrots from crossing with Queen Anne’s Lace.

Caging is just one physical barrier to prevent cross pollination between vegetable plants. It may take a little planning, but it’s a simple process that will have you saving your own open-pollinated and heirloom vegetable varieties.

For more information on open-pollinated and heirloom vegetables, check out The Definition of Heirloom Vegetables, Hand-Pollinate Cucumbers, Pumpkins, and Squash, and Determinate Versus Indeterminate Tomato Plants.