The Facts of Life About Melons and Squash
Mixed breeding of melons or squash only matters if you want to save seed from one year for the next. Unlike corn, which can cross the first season, vine crops will never show the results of cross-pollination the first year. It's what the bees were up to the previous year that can cause strange-looking vegetables. Seed companies isolate vine crops for good reason: If two crops' blossoms mix this year, it will show up in the seed you buy for next year.
Sometimes, even with controls, commercial seed may have one or two weirdo seeds mixed in, and you may raise a strange-looking zucchini. But it isn't because of anything that happened in your own garden.
Each vine crop species keeps to its own kind. Summer squash will cross with each other, but not with cucumbers. Cucumbers will inter-breed, but won't cross with pumpkins. Muskmelons will cross with each other, but not with watermelons. Winter squash, summer squash and pumpkins are closely related, and may cross among themselves. Gourds are species unto themselves, but occasionally cross with summer squash.
If you want to grow two kinds of summer squash and you plan to save the seed, plant the squashes at least 100 feet apart to to reduce the possiblity of bees mixing pollens, and pollinate the flowers yourself. It's usually best to stick with commercially grown, disease-resistant seed for your main yield, and only plant home-grown seeds for fun.
A point on hybrids: Don't try to save the seed of hybrids. They don't reproduce themselves. Instead they revert back to the traits of their parent plants, usually of inferior quality.
Making Your Own Crosses
To hand pollinate, first identify male and female buds that will open the following day. They often have a yellowish color lacking in younger buds, and gap at the tip. Mark these buds with tape so you can find them the next morning. That morning, pick the marked male bud (which has a straight stem behind the flower) and carefully tear the petals off, exposing the pollen-bearning anther in the center. Gently open or tear off the end of the female bud (which has a small fruit behind the flower) to expose the stigma. Using the stripped male flower as a pollen-transfer stick, daub the pollen onto the stigma.
The tiny fruits behind any pollinated female blossoms will grow into full-sized vegetables, and the plant continues to produce blossoms. The plant's natural goal is to produce seeds that will produce more plants, thus perpetuating the species. Once the seeds within each fruit reach a certain size, the plant stops producing more female flowers for more fruit--it's job is done.
Photography by National Gardening Association