Melon Seed Saving
If you want to maintain a particular variety that you love and save pure harvested seed for replanting, you’ll need to prevent bees from transferring pollen from other varieties of the same species. If heirlooms are not allowed to cross, they produce plants with fruits that look and taste like their parents. Known as open-pollinated or standard varieties, heirlooms differ from modern F1 hybrids, whose offspring don’t breed true.
There are two basic ways for the home gardener to control pollen flow between varieties of the same species: isolation by distance, and hand pollination. Since melons and watermelons belong to different species and don’t cross with each other, I recommend that you begin with isolation. Limit yourself to one variety of melon and one variety of watermelon that you value and know to be heirlooms rather than F1 hybrids. Plant them in the same garden but make sure that they are at least eight hundred feet to a half mile from other varieties with which they could cross-pollinate. Check with your neighbors to see if they’re planning to grow these species. If not, you can let nature take its course.
If you can grow melon and watermelon for the fruit, you can grow it for seed, too. In most cases, when your fruit is ready, so are the seeds. It’s easy to scoop them from the cavity of a muskmelon or honeydew. But because watermelon seeds are scattered and embedded in the flesh, they present a bit of a challenge. Either collect the seeds after the fruits have been eaten and seeds set aside or pick them out in advance and put them in a colander, reserving the flesh for fresh eating or juicing. Rinse seeds under running water, gently rubbing to remove stickiness and tissue; then shake off the water, blot extra moisture from the bottom of the colander with a paper towel, and turn the seeds out onto sturdy, absorbent paper plates (or coffee filters) that are labeled with the variety name. If your main concern is to maximize mature seed production, allow the intact harvested fruit to ripen past “market maturity” before processing seeds. (Don’t wait too long though: watermelon seeds can begin sprouting in vivo.) Some growers prefer to soak seeds for a few hours—or even ferment them in water for a day or two—in order to remove attached pulp before rinsing. Dry the seeds at room temperature, occasionally turning them over, until they can be cracked or snapped rather than bent.