How to grow Watermelon
in the US

Watermelon is a proper summer treat. Growing your own is a bit of a challenge, but so rewarding. Nothing beats a homegrown slice on a hot day, you know what I mean.

Sowing

Watermelon needs warm soil, around 70°F (21°C) or more, so wait until after your last frost date. For zones 3-5, sow seeds from May to July, depending on your specific zone. For zones 6-8, April to June works well, and for zones 9-10, you can start as early as January right through to July. Plant seeds about 1 inch (2.5 cm) deep, either directly where they're to grow or in small pots indoors a few weeks before transplanting. Give them plenty of space, maybe 3-4 feet (90-120 cm) apart, as they love to spread out.

Growing on

If you started seeds indoors, you'll need to harden them off properly before planting them out. Just a week or so, gradually getting them used to the outdoors. Once all danger of frost is gone and the soil is warm enough, plant your young plants into their final spot. They'll want good room, so give them at least 3 feet (90 cm) between plants, maybe more if you can. You can let them trail on the ground or, if you're short on space, try growing them up a sturdy trellis – just make sure to support the fruit as it gets heavy.

Looking after it

Water deeply and consistently, especially when the plants are flowering and the fruit is setting. They're thirsty things. A good mulch around the base will help keep that moisture in and suppress weeds. You can give them a balanced feed every few weeks too, especially if your soil isn't the richest. Keep an eye on the leaves; healthy leaves mean happy fruit.

What goes wrong

Slugs and snails can be a pain, especially when the fruits are small. I usually put down some crushed eggshells or try beer traps. Aphids can show up, but a strong jet of water often sorts them out. Cucumber beetles and squash vine borers are trickier, so keep an eye out and remove them by hand if you see them. Anthracnose can be an issue in humid conditions, good air circulation helps.

Harvest

Watermelon takes about 85 days from sowing to harvest, so you're looking at August or September for most. You'll know it's ready when the spot on the ground turns yellow, and the tendril nearest the fruit dries up. Give it a good thump; a dull, hollow sound is a good sign. Cut it with a sharp knife, leaving a bit of stem. Store them in a cool, dry place, or pop them in the fridge once cut.