Will watermelon and cantaloupe cross-pollinate and produce bad-tasting melons? Is it possible for a vine that had cucumbers growing on it earlier in the season to produce a cantaloupe? I could swear that we now have what looks like a melon on a vine that had cukes before…
The short answer is, no. It’s fine to grow watermelons and cantaloupe side by side. Cross-pollination between melon varieties may occur, but not between watermelons (Citrullus lanatus v. lanatus) and cantaloupes (Cucumis melo ssp. melo v. cantalupo), as they are two different species. In addition, cross-pollination affects not the melon produced that year, but the melons one might grow from any seeds produced inside that melon. According to Sue Stickland’s Back Garden Seed Saving (Chelsea Green, 2001), “commercial seed growers are recommended to isolate melon varieties by 500-1000 meters” or “bag and hand-pollinate the flowers” to keep unwanted hybridization from happening.
The same principle holds true for cantaloupe (Cucumis melo and cucumber (Cucumis sativus): they are indeed in the same plant family (Cucurbitaceae), but they are different species. If your vines were planted close together, you might not have realized there was a melon developing in among the cucumbers–and if you planted the vines from seed, it’s very possible the seed packet contained a surprise cantaloupe!
You may find this information from Iowa State University Extension about cross-pollination among vine crops interesting:
“Since they have a similar flowering habit, bloom about the same time, and are members of the same plant family, it is logical that gardeners might assume that squash, melons, and cucumbers will cross-pollinate. Fortunately, however, this is not true. The female flowers of each crop can be fertilized only by pollen from male flowers of the same species. Cross pollination, however, can occur between varieties within a species.”
An article on fruit set in the
Cucurbit family from University of California, Davis (which also has information on how to hand-pollinate plants when necessary) says much the same thing:
“A common misconception is that squash, melons, and cucumbers will cross-pollinate. This is not true; the female flowers of each can be fertilized only by pollen from that same species. Varieties within each species, however, will cross-pollinate.”