Planting Guide and Seed Saving Notes for Watermelons

Watermelons (Citrullus lanatus)

Oh the glory days of summer! Vine-ripened, homegrown watermelon is one of the greatest pleasures of earthly existence. While most are familiar with crimson red flesh and bright green rinds, watermelon actually come in a wide range of colors and sizes. A simple slice will suit most, but for those looking for new preparations, try it with salt and chili powder, a common street food in Latin America, preserved as jam for the winter, or a jar of pickled rinds to go with a bit of ham. And, while everyone has their own method to check for ripeness, an old method is to harvest when the tendril opposite the fruit stem had dried up.

Nutrients: vitamins A and C (very high) B6, thiamin, pantothenic acid, potassium, magnesium, copper, phosphorous.

How to Grow Watermelons from Seed

Bed Preparation

Watermelons are frost sensitive annuals that prefer full sun and fertile, evenly moist soil that is well drained. Choose a site with plenty of space. Fruits grow on vines that sprawl 8'-12' depending on the variety. Bush type varieties require less space

Planting

Direct seed a couple weeks after the last frost when soil temperatures have warmed. Optimal soil temperatures for germination are 70-95°F. Planting in hills allows soil to warm faster and provides better drainage. Space hills 3' apart in rows 3' apart for bush varieties and in rows 8' apart for vining types. Sow seeds ½ inch deep. Seeds will germinate in 3-10 days. Thin to 2 to 3 plants per hill. Ensure plants receive 1" water a week, through rain or irrigation, until fruits are softball size when plants require less water for successful fruit set. Mulch around seedlings to conserve moisture and suppress weeds.

In cooler regions, seeds should be started indoors 3 weeks before the last frost date. Sow ½" deep in 3-4" pots. Transplant outdoors as you would when direct seeding. Avoid disturbing the roots as much as possible when transplanting.

Harvest

Depending on the variety, watermelons take 80-100 days to ripen. Vine ripening will increase the sweetness of melons. If you pick them before they are ripe, the melons will soften but won't get any sweeter. To determine ripeness, look for tendrils near the fruit to dry and turn brown and the bottom of the watermelon to turn yellow. Twist melon to remove from vine.

How to Save Watermelon Seeds

An insect pollinated annual, watermelons will cross readily with each other and citron melons, but not with other types of melons. Fruits will usually have a mix of mature and immature seeds inside and you can separate these by hand, or we prefer to put them in water and the non-viable seeds will float. Skim these off and continue to stir and skim until no more seeds float to the top. Rinse the remaining seeds well and spread on a screen or many sheets of newspaper and allow to dry thoroughly before storing. This can take 2-4 weeks depending on the humidity in the air.