I have often had questions about plants that appear to have cross-pollinated, and the gardener was disappointed in the fruit and was looking for ways to keep this from happening again.
All of us want what we plant to yield the fruit or vegetable we expect, and along with that we want to use seed that has not been altered in some way and is true to the claim that it is heirloom or organic. As a result of this trend we want to save seed for a future season (even future years) but we want seed that is “true” to begin this important project.
Here is an instance when good intentions at the production level can be compromised — and the plants without malice did it all by themselves. This season a friend bought what promised on the package to be stringless pole beans. What the friend got was very healthy prolific plants loaded with beans, but they had strings — lots of strings. The friend was disappointed, of course, and wondered what happened — and so did I. I finally discovered what probably happened — and it was not the fault of the seed manufacturer.
Here is the link to a very informative website: “Seed Savers Exchange”: http://tinyurl.com/o6r8pm8. On this page you will find good information concerning this very thing, examples of how this can happen and how to avoid having unpleasant results should you decide to save seed for your future gardens, or to produce seed you will pass on to your children and grandchildren:
Regarding the bean situation I mentioned above, it is interesting that bean flowers are self-pollinating and almost never cross-pollinate. Problems come when two white bean varieties are planted side by side. Then you will probably get something such as what may have happened to the stringless vs. the stringed pole bean and actually, one white bean looks like another unless you are a bean expert.
Here are a few examples of how this can happen to other vegetables:
•Beets make seed every other year and will cross-pollinate. To harvest true seeds, varieties must be separated by 1/2 mile from other beets the second year when they make seed.
•Broccoli is a biennial, and also will cross-pollinate with other members of the Brassica oleracea family, which consists of many members: cabbage, cauliflower, kale, Brussels sprouts, Savoy, and Chinese kale, for example. So to get true seed, these plants need to be grown at least 1 mile apart
•If saving seed from carrots you need to know they are biennial and cross-pollinate and should be isolated the second year from other carrots and Queen Anne's lace. If you see carrot seed heads, you will note the resemblance.
•I thought corn was very interesting — “All corn varieties are wind-pollinated and will cross with each other. Varieties should be hand pollinated or isolated by 1 mile to ensure purity.”
•Cucumbers will cross-pollinate with squash and gourds, so if raising them for seed purposes, isolate 1/4 mile from these other family members.
•In order to raise vegetables for seed, many of which make seed every other year, you will need to treat them, whether bulbs or roots, as you would a flowering plant or bulb. They should be dug by or before the first frost, soil removed, given time to dry and saved in a cool dry place to be planted the following year. This is when these plants will flower and make seed.