How to Grow Watermelon

Nothing tops a fresh, homegrown watermelon. Commercially grown watermelons are picked early so that they keep well during shipment. However, much of the sweetness that gives watermelon its delicious flavor isn’t produced until right before the fruit reaches peak ripeness. This is just one of the many reasons to grow your own watermelons. Here are some instructions on how to grow watermelon.

Watermelons come in a variety of shapes and sizes, each of which may have their own unique set of requirements to help them flourish. All varieties of watermelon need ample heat over the course of an entire summer. Check maturity dates on the variety you choose to grow to be sure you have sufficient warmth and length of growing season for your melons to be successful.

If you live in a cooler region, you can choose shorter season variety such as “Sugar Baby” and/or start your seeds indoors to get a head start. Watermelons also vary in size, which will require more or less space for their long vines to stretch out and sometimes behemoth fruit to thrive. Dwarf melons and any variety weighing less than 8 pounds, such as “Snack Pack” are great for vertical gardening.

Speak with local growers to find out if there are specific varieties of watermelon that thrive in your area.

Watermelons should be grown over the course of long, hot summers. They need soil temperatures of at least 70° F for good seed germination and air temperatures up to and exceeding 80° F during the day. Plan for at least 3-4 months for most varieties, though shorter season varieties are available.

Sow watermelon seeds or transplant seedlings at least 2 weeks after the last average frost date for your area. Start seedlings indoors several weeks early to get a head start. Be sure not to plant watermelons too early. If the seeds or seedlings get shocked by the cold the plants may still grow but not bear fruit. It’s best not to transplant seedlings outdoors until they are 4 weeks old and temperatures reach 75° F during the day.

Watermelons can be grown in any region with enough warm days for them to mature. This is usually zones 3-11.

Depending on the variety of watermelon, you will need a space of 2-12 feet per plant in order for your melons to succeed. Choose an area of the garden where the melon vines have plenty of room to stretch out and won’t be trampled or otherwise disturbed. Be sure they receive full exposure to the sun (the more sun the better) and have really good air circulation. Don’t group them too close together.

Watermelons should be grown in sandy soil. They’ll do well in any soil that is loose and drains really, really well but a fertile, sandy loam is the best. Add lots of mature compost or aged manure before planting. Be sure your soil is deeply tilled so the roots have plenty of space to grow. Test the soil to be sure you have a neutral pH of 6.0 – 7.0.

Watermelons like to grow on hills. This allows the roots to grow deep and the water to drain really well. Sow about 6 seeds ½ inch deep in each hill and keep the hills spaced 2-12 feet apart depending on the variety. Do not plants seeds until the danger of frost is long gone and soil temperatures have reached at least 70° F. Thin to the strongest 2 or 3 plants per hill. Leave only one plant per hill in shorter growing regions to expedite the fruiting process.

You can also start your seedlings indoors about 4 weeks before you plan to transplant them outside. Sow them ½ inch deep in 4-inch pots. Set them in a sunny window and apply bottom heat if necessary to be sure the soil is at least 70° F. Once they are 4 weeks old and about 4 inches high, you can transplant them outdoors if daytime temperatures have reached 75° F. Harden them off before transplanting. Set them outside during the day only and bring them inside at night. Increase the amount of time they spend outside each day for about a week. On the last day, leave them outside in their pots overnight and transplant into the ground the next morning before it gets too hot.

Watermelons need lots of water as you might have guessed, usually about 2 inches per week. They should be watered generously, especially as they begin to bear fruit. Make sure the soil never dries out completely though it should not be left soggy at any point. Overhead watering can foster disease, so try to water at the base of the plant and in the morning when possible.

Watermelons need several feedings throughout their long growing season in order to really be successful. Try a good organic, liquid fertilizer or compost tea. Feed once when they are transplanted, or about 4 weeks after sowing seeds, again as soon as they bear fruit and once more about 2 weeks later. Some gardeners prefer to start with a fertilizer rich in nitrogen and switch to one that is rich with phosphorus and potassium as the fruit begins to appear.

In general, watermelons should not need much, if any, pruning. In colder regions, you can remove any small fruits and all flowers. This will encourage the plant to focus its energy into the larger fruit and expedite the maturity process before the cool weather sets in.

Allow for 100 days to maturity for most varieties of watermelon. Watermelons will tell you they are ripe or near ripe by producing a strong, vibrant small. The limb where they are attached to the vine will also turn brown. The bottom of the melon will turn from a light straw color to a rich gold, orange or yellow color. You can also try the “thump” test. Thump the melon and listen closely. Ringing melons are not yet ripe. A dull sound, however, indicates that they are ready for harvest. Be careful though, they will remain dull as they become over ripe.

Harvest your watermelons as soon as they ripen on the vine for the sweetest flavor. They should pick off easily with not need to cut or clip the vine.

As the watermelons begin to grow, try to keep them off of the ground. Carefully slide a board or piece of cardboard beneath them. This will help prevent rot, disease and keep away pests.

Watermelons taste better when picked in dry weather.

Hand weed carefully and early on. Use mulch to keep down weeds. It will also warm the soil and maintain moisture, particularly in cooler climates. Lay the mulch before the vines begin to grow, otherwise they will be more difficult to navigate later on.

Male plants blossom first. Females blossom a week or so later. Only female plants will bear fruit.

Despite some reports to the contrary, you don’t want to pinch off growing shoots as the fruit begin to ripen. Watermelons need all of their leaves to produce the sugar that makes them so delicious.

Try using plastic mulch in the spring to help warm the soil in order to get your melons planted early.

Watermelon is a great source of vitamin C and antioxidants.

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