Watermelons (Citrullus lanatus) are members of the cucurbitaceae family of plants. They are grown as annual fruit, although it also is regarded as a vegetable. There are 1,200 varieties of watermelons throughout the world. Watermelons have been grown for centuries and are indigenous to the Kalahari desert of Africa.They will thrive in zones 8 and 9, 12 through 14, and 18 through 21.
How to Plant a Watermelon Patch
Choose an area in your vegetable garden that has full sun and rich, fast-draining soil. If in doubt about the soil, amend it by turning it over with a shovel or garden fork to a depth of 4 to 5 inches. Work in 1 inch of organic matter, such as compost.
Level out and smooth the area. Water thoroughly and let it drain for a day.
Create hills of soil, approximately 2 feet in diameter and spaced 6 feet apart in rows that are 7 to 10 feet apart. Place a 2-inch high berm of dirt around each of the hills to help with irrigation. This helps to reduce the likelihood of the leaves and fruit from being inadvertently saturated during irrigation.
Poke five or six holes into each hill to a depth of 1 inch; spacing should be 4 to 6 inches apart. Drop a watermelon seed into each hole and cover each seed with 1 inch of dirt.
Place planting stakes at the beginning and end of each planted row. Water the hills just enough to moisten them.
Inspect your watermelon patch daily and thin out each hill to three plants per hill once the seeds have sprouted. Germination time for watermelons generally is 7 to 10 days.
Planting Watermelon Seeds Indoors
Start the watermelon seeds indoors approximately 3 weeks before planting them outside, according to the University of Illinois Extension.
Fill up cell packs or peat pots with a potting mix. Firm down the dirt in each planting cell or peat pot by hand until the dirt is well-packed.
Water each planting cell or peat pot and allow them to drain.
Poke 1-inch deep holes into each cell or peat pot and drop in 2 watermelon seeds. Cover the seeds with potting mix.
Place the watermelon seeds in a bright, warm area where they will receive 6 to 8 hours of light per day with a temperature of 80 to 85 F.
Inspect the seeds once or twice a day and spritz the surface of the soil with garden sprayer or plant mister when the soil appears dry.
Plant the seeds in your garden when they have grown to approximately 2 to 3 inches tall.
Create hills of soil, approximately 2 feet in diameter and spaced 6 feet apart in rows that are 7 to 10 feet apart. Place a 2-inch high berm of dirt around each of the hills to help with irrigation. Dig holes in the hills that are slightly deeper and wider than each of your planting cells or peat pots. Space the holes at 4 to 6 inches a part with three plants maximum per hill.
Remove watermelon seedlings from their cells by pushing them out from the bottom up, With peat pots, place the watermelon sprout in the hole and cover it with soil. Water each at the base of the hills.