Barb Henny has had success with ‘Crimson Sweet’ watermelon in her Lake Jem garden. ‘Moon and Stars’ was less productive. Contact her at

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Perfect Slices
by Barb Henny       #Fruit   #Plant Profile   #Vines

Delicious seeded and seedless varieties are available.

If you’ve ever grown cucumbers in your garden, you can grow watermelons. Cucumbers and watermelons are in the same plant family and have very similar growing requirements. To grow watermelons, all you need is a little more space for the crop’s vigorous vines to run.

Watermelons need a long, warm growing season. Frost will damage or kill seedlings. Florida’s warm conditions make our state first in the nation in watermelon production, especially in the winter months when Florida becomes the only domestic supplier from December through April.

All Florida zones can plant watermelons in March and all zones can plant a fall crop in August. If you have a luxuriously large garden, you can choose a seedless watermelon variety to grow. Seedless watermelons require two varieties be grown at the same time to ensure pollination. Seeded varieties do not need a pollinating companion and may be a better choice for most home gardens.

Many Florida gardeners still practice direct seeding and bare-ground culture. But starting seeds in small pots will give you a three to four week head start and increase chances for success. Fill a 4-inch plastic pot with potting soil and moisten the soil. Plant two seeds into each pot about 1½-2 inches deep. Seeds take about 10 days to germinate. Seed germination will be slow if soil temperatures are less than 70 F. Some growers allow both seedlings to grow in one pot/hill. Others pinch to one seedling per pot.

Watermelons need space. Allow 5 feet between plants and 10 feet between rows. Mulching is recommended to keep the soil moisture even and keep weeds in check. Black plastic mulch warms the soil, allowing earlier planting. It is true that watermelons can be trellised, but you must provide a sling to tie each fruit as it develops.

Watermelons come in three categories: mini (4-8 pounds); personal (8-12 pounds); and picnic (up to 30 pounds or more). If you’re growing on a trellis, make sure it can handle the weight.

Water the transplants when you set them out, and then water once or twice a week. This crop needs a steady water supply. Not too wet, not too dry.

Fertilize 10 days after transplanting, using your favorite product. Fertilize again – lightly – after the watermelon vines bloom. After this bloom stage it is very important to maintain even moisture in the soil. If your immature watermelons get dry and then a heavy rain event occurs, the sudden uptake of water may cause the rind to split and the crop will be lost.

Weeding can be done with a hoe until the vines fill in. After that, weed by hand to deprive insects and diseases a safe harbor from which to attack your crop. Be on the lookout for caterpillars including armyworm, budworm, earworm, pickleworm, and cabbage looper. Taking care not to twist the central vine, gently roll the developing melons over and look underneath. Caterpillars hide and eat the rind on the underside of the fruit. If needed, treat with Bacillus thuringiensis (Bt) according to package directions.

Transplant watermelons to ensure a good stand.

Foliage diseases on watermelons (and cucumbers) can get ahead of a gardener very quickly and can be very discouraging. At watermelon planting season, timing is everything for disease control. Plant before the rainy season starts in spring, or plant after the rains stop in the fall. Prevention is the most effective cultural control for leaf diseases.

Depending on the variety, your watermelon should be ready to harvest from seed in 80 to 100 days. It’s oh so easy to tell when cantaloupes (also in the same plant family with watermelons and cucumbers) are ripe … the fruit falls off the vine. With watermelons, the vine will turn brown but does not release the fruit.

Some harvesters are expert at “thumping” the watermelon and detecting a change in the sound. I look at the spot on the bottom of the watermelon where the fruit was laying in the field. An unripe watermelon has a white spot; a ripe and ready watermelon will have a creamy yellow spot.Take your warm, freshly harvested watermelon from the garden to the kitchen sink and wash it under running water. Use a vegetable brush to remove any soil or gritty sand clinging to the rind. Pat dry with a clean terry cloth towel.

Watermelons do not continue to sweeten or develop more color after harvest. If you must store your harvest, place your watermelon in a cool, shaded area between 50-60 F. Storage life is about 14 days for uncut watermelons. Extended time in a refrigerator at temperatures less than 45 F can cause a loss of flavor. Once cut into cubes or slices watermelon has a very short shelf life, so eat your sweet fresh harvest promptly.


A version of this article appeared in the print edition of Florida Gardening Volume 21 Number 3.
Photography courtesy of Barb Henny.


Posted: 05/11/18   RSS | Print


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