Now that it feels like summer, you may be starting to crave watermelons. Although there may be some shipped from afar on the grocery store shelf, there's no better tasting watermelon than ripe-picked home-grown garden-to-plate (or more likely hand-to-mouth) pink wedges. Maybe you've tried to grow watermelons before- ordering seeds from a catalog based on salivary gland geared descriptions but then never had the pleasure of a single ripe fruit? That's because watermelons are warm climate plants that need a long season to mature. Here's some more info about their background followed by tips for how to successfully grow watermelons in the northeast this summer.
Watermelons (actually in the gourd family) are characterized by a shiny, thick rind—usually green in color—and a juicy, fleshy center. Watermelon originated in southern Africa, growing wild in the Kalahari Desert. They have been cultivated since the second millennium B.C.; there were even watermelon seeds found in King Tut’s tomb. Watermelons are about 92% water, thus earning their soggy moniker. China currently holds the title of biggest producer in the world, and Japan the title of “weirdest producer”—some Japanese growers outfit young fruit in a glass box, forcing mature watermelon into a square shape that fits perfectly in the refrigerator.
The Seed Library carries one variety (soon to be more!) of watermelon—Sugar Baby—which comes as an Art or Library pack. Like Japanese square watermelon, they won’t crowd your ice box (they’re 12 inches across and round), and they pack a wallop of flavor. Sweet and small, these bowling-ball-like fruits are perfect for the fridge or the picnic blanket.
Growing watermelon is not too difficult. Sow seeds indoors about two weeks before your last frost, then transplant two weeks after last frost. Be sure to use a fairly large 4- or 6-pack (or other container) for watermelons, as they grow quickly and use up potting soil nutrients speedily. Alternately, direct sow watermelons 1-5 weeks after last frost date; any later than this and your fruits may run out of time to mature fully before cooler weather sets in. (Here in the Hudson Valley, this window is approximately May 21-June 15.) Provide plenty of compost and water early in the season; as fruits begin maturing, withhold water to increase sweetness. Space 24" apart in rows 60"-80" apart. If planting in an area that has grown cucurbits in the past, consider covering the young plants with row cover to keep off cucumber beetles, which can cause plants infect young plants with bacterial wilt.
The hardest part of growing watermelons is determining when they are ripe. Unlike muskmelons, which slip easily from the vine when ripe, watermelons require some sleuthing. Here are the clues to look for: 1.) A bright yellow patch upon the part of the watermelon that's resting on the soil; 2.) the drying out and browning of the vine tendril closest to the fruit; 3.) a reverberating, drum-like sound (not a thud!) when you tap on the watermelon; and 4.) discernible but subtle ribs that can be felt when you handle the fruit. You'll get the hang of it, though even experienced watermelon growers occasionally pluck a fruit that turns out to be underripe; sadly, the fruit does not ripen at all after being harvested.