Heirloom Expert: Avoid Cross-Pollination

These tricks and resources can help you keep your heirloom crops from cross-pollinating.

| Winter 2012/2013

  • Heirlooms can be planted right next to each other without worry of this season’s fruit being affected.
    Photo by Fotolia/asferico

Is there a list anywhere that has the spacing requirements between plants so they will not cross breed? I know tomatoes need 15 to 20 feet from each other, but what about squash, beans, melons and other garden plants? I have started an heirloom garden club and we would like to know how to keep our garden an heirloom garden.

I assume you're saving seeds, since that’s the only reason to worry about cross-pollination. Heirlooms can be planted right next to each other without worry of this season’s fruit being affected; it’s the harvested seeds which might not grow true.

Susan Ashworth’s Seed to Seed is a good primer as is our own Jere and Emilee Gettle’s The Heirloom Life Gardener.

There are lots of resources online which will give you the distances between similar species including the USDA. In fact, everyone who grows seeds for a living has a different distance for isolation and different ways to keep their seed pure.

With the distance between corn cultivars being 2 miles, and 5 miles for spinach, it’s impractical for a gardener or small farm to use distance as the only way to isolate crops. But there are other ways to isolate crops so they don’t cross-pollinate. Growing one variety of each type of plant is one way, but that’s not very exciting. Grow varieties in their own separate screened-in cages, cover individual flowers with bags or time planting so that different cultivars don’t flower at the same time.

I can only speak for myself when discussing tomatoes. Since they are self-pollinating, I don’t worry about crossing. It happens sometimes as an insect forces its way up into the flower, but most of the tomato seed I save looks just like their parents.



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