Your summer watermelon crop should be growing strong, and now is the time to devote a little attention to your patch of fruits. Watermelons need extra care once they germinate and start vining. The heat of summer spurs growth seemingly overnight. Once they fill in your garden area with vines, they will be better able to withstand pest attacks and drought. In warm parts of the country with two growing seasons (spring and fall), you can even try to replant a failed watermelon patch now and get a harvest before frost.
Here are some summer chores to do in your watermelon patch.
For gardeners in southern climes, such as Texas and the deep south, you can seed a crop of watermelons as late as early July and get mature fruits before the cold weather hits. The key is to select fast-maturing, disease-resistant, hybrid varieties and keep them well watered, fertilized, and bug-free.
Here are some varieties to try. They all mature in about 80 days from seeding and produce 20- to 25-ound fruits unless otherwise noted.
'Gold Strike' is a quick-growing hybrid with orange flesh.
'Jube-ette' is a 'Jubilee' type that's smaller and produces sweet, dark red, firm flesh.
'Redlicious' is a new diploid variety with deep-red flesh and high sugar content.
'Yellow Doll' is a ice-box type with crisp, extra-sweet, yellow flesh. The 10-pound fruits mature in only 70 days.
'Gem-Dandy' is a seedless variety with bright red flesh and high sugar content that lasts for weeks in the field.
Hills of watermelon plants need to be spaced about 4 to 5 feet apart. The space between hills is prime real estate for weeds to move in before the watermelons have a chance to take over. Eventually watermelon vines can grow 20 feet, but you may need to clear the way for them.
Cultivate the open space between hills with a hand weeder, such as a scuffle hoe. For large patches, consider running a tiller or high wheel cultivator between rows or hills to kill weeds. Once the weeds are gone, mulch between hills with pine straw, old newspaper, or hay mulch. Lay down a 3- to 4-inch-thick layer of straw or a layer of newspapers five sheets thick. Northern gardeners might consider using black plastic mulch around plants to speed their growth while blocking weeds.
Mulching not only controls weeds, but it helps retain soil moisture. Watermelons love water. Established plants have moderately deep roots so watering may not be necessary unless the weather turns dry for a prolonged period. That being said, if you have drought conditions or a newly planted crop, water a few times a week. Apply water so it sinks at least 6 inches deep into the soil. You can tell if your plants need watering if in the morning the leaves look wilted. Wilting leaves in the afternoon are natural and caused by the heat of the day, but morning wilting is a sign of water stress.
Since watermelons grow so fast, they need extra fertilizer to keep them going. Incorporate compost into the soil when planting. Then side-dress the plants twice during the summer with additional fertilizer to keep them producing. Sprinkle 1/2 cup of balanced fertilizer around each plant when the vines begin to run, and again when the watermelons begin to set fruit. This will help them produce the largest and tastiest fruits possible.
While some watermelon varieties are resistant to many plant diseases, it's still a good idea to stay out of the watermelon patch when the leaves are wet. Simply rubbing against the leaves spreads disease spores between plants.
Insects are another problem. Two of the most troublesome insects are cucumber beetles and squash vine borers. Cucumber beetles feed on young leaves and flowers. While their feeding is detrimental to your plants' health, it also spreads diseases, such as bacterial wilt. Control cucumber beetles with sprays of pyrethrum botanical insecticide.
Squash vine borer damage isn't usually noticed until the vines begin to wilt and die. At this point the young larvae have bored into the vines. Look for the sawdust-like frass or droppings along the vine where the larvae have entered.
If you see signs of borer activity, inject Bacillus thuringiensis (Bt) into the stem. Bt will kill the larvae but not harm the plant or other insects or humans. You can also physically remove the larvae by slitting the stem with a sharp razor and picking out the borer. Cover the stem with soil afterwards so the vine can heal.
Q. My watermelons are not very sweet. Is that because they crossed with other vine crops in my garden?
A. Watermelon varieties can cross with one another but not with other related plants, such as muskmelons, squash, pumpkins, or cucumbers. However, cross-pollination doesn't affect the quality of the fruits unless seeds are saved and planted the next year.
The lack of sweetness in your fruits is more a result of water stress due to low or high rainfall, poor soil fertility, cool weather, or too short a growing season. Next year beef up the fertility of your soil by adding compost, and try some different varieties more adapted to your region.