How to Space Tomatoes for Noncross-Pollination

Plant modern open-pollinated tomato varieties at least 10 feet apart to prevent cross-pollination. Modern open-pollinated tomato varieties are hybrids, which means they are cross-bred, but they have been stabilized to breed true to the parent. Ordinarily hybrid tomatoes produce seeds that can have a variety of characteristics from any of the parent tomatoes, and they don't breed true to the parent. Also, cross-pollination only affects succeeding generations. The tomatoes from the first year aren't affected by cross-pollination, so if you aren't saving seeds, this doesn't matter.

Plant heirloom tomato varieties farther apart, 20 to 25 feet between different varieties of tomato plants. Heirloom tomatoes are older varieties, not hybrids, with seeds that produce plants just like the parents, although there can be some variation within each variety. If you are saving seeds from your heirloom tomato plants, it is important to plant them far enough to reduce the risk of cross-pollination as much as possible. The closer the plants are spaced, the greater the possibility of cross-pollination.

Plant other pollen-producing plants between the different tomato plants. This draws the bees, so they aren't as likely to cross-pollinate the tomato plants. Flowers or flower-producing vegetables, such as squash, beans or peas, will attract bees.

Choose heirloom varieties that flower at different times so cross-pollination is less likely to happen.