Genetic Integrity in the Garden

An article from our friends at Sow Organic.

For those of you who wish to save your own seeds, here are some tips to help arrange a garden that does not interbreed.

Plants can only cross-breed when they are in flower. If you grow more than one member of the same species, you can prevent crossing by culling any flower spikes of the undesired variety. This requires daily personal attention and adds new personal participation in the gardening process.

Most garden plants do cross with other varieties of the same group (species). Example: carrots, corn, cabbage, peppers, squash.

Some do not cross. Tomato & lettuce are both self-fertilizing and only need to be separated for visual distinction and harvesting ease.

There are four groups in the squash family. One of each may be grown in close proximity to the others and crossing will not occur. In one corner of a garden you can grow Delicata (pepo), Butternut (moschata), Green & White, Cushaw (mixta) and Green Hubbard (maxima). If the garden areas are large enough to separate squash patches by up to 200 feet, with garden, trees, or scrub growing in between, you may grow another set of the four kinds of squash. Basically these groups are as follows:

• PEPO: summer squash; (scallops, zukes, crooknecks), pumpkins, acorns, delicatas, spaghettis, sweet dumplings
• MAXIMA: buttercup, marrow, banana, kuri
• MIXTA: cushaws
• MOSCHATA: butternuts, tahitian

Watermelons only cross with other watermelons, and melons cross only with other melons. Cucumbers cross only with other cukes. (Watch out, Armenian cukes are really a melon and not a true cucumber.) Decorative small gourds (yellow flowers) are pepo squash and will cross with other pepos. Large gourds (white flowers) are in the laginaria family and will not cross with squash.

Beets and chard are in the same family and will cross. They are wind-pollinated, so any time these flower at the same time they will be in jeopardy. Red Chard will cross to Green Swiss Chard, and either will cross to beets, corrupting the integrity of root types.

Carrots will cross with other carrot cultivars and also the wild weed, Queen Anne's Lace.

The mustard, cabbage, and radish family, known as Brassicas, can also cross within their family. Most of these pollinations are done by bees, although in close proximity the wind will also affect them. Bees tend to harvest from one variety at a time. They will find the line of broccoli in flower and work it in a straight line and then head back to the hive. Mustards cross with mustard and also the chinese green mizuna. The Oleracea group (sub-part of Brassicas) includes broccoli, cabbage, kale, and kohlrabi. Any of this group will cross with each other if they flower at the same time.

Radishes will cross with each other. You can grow 3 radish varieties in your garden, then only allow one of them to spike to seed. Pull to harvest the others and your seed will stay pure. Keep an eye out for wild varieties. Many weeds are in the Brassica family and will cross with the selected cultivars.

Back to Index