How To Grow Watermelon

watermelon Watermelon

Please see individual varieties for specific product information, but in general the growing information will be the same for all melons including watermelons and cantaloupes. The majority of the information on this page was provided by the University of Arkansas Cooperative Extension Service Watermelon Home Gardening Series; download the complete pdf file with FAQ’s for more information or click here to visit the website.

Average Days To Maturity: 85 days for the most popular varieties (ranges from 70 to 130 days among all)

Distance Between Rows: 8 feet

Spacing Between Plants: 48 inches

When To Plant: Watermelons should be planted after all danger of frost has passed when the weather is warm. Watermelons can be grown from seed or from young transplants. The earliest Charley recommends that you plant your watermelons is late April.

Planting Tip: Watermelons, like Cantaloupes, do well when mulched with black plastic. Lay out a layer of black plastic over your row then cut holes in the plastic and plant your transplants. The plastic will warm the ground quickly, help retain moisture and help control weeds.

Average Yield: 8-40 pounds per 10 foot row

Preparation and Care: Watermelons do best in fertile well drained soil. Add a basic starter application of 10-20-10 fertilizer to the soil during preparation prior to planting. Watermelons do not like it when they are too wet or too dry. The best quality of melons are produced when the vines are healthy, the temperatures are warm but not extremely hot and the weather is on the dry side at harvest.

Watermelon vines can be trained to grow in rows. Gently move the vines to grow in the desired direction.

Watering: Water your garden (cantaloupes and everything else) once a week with a 8-12 hour soaking. This will allow the soil to absorb an adequate amount of water and also limit the time you spend each week watering.  If you use a sprinkler to water, do this during the day so that the plants will have some time in the evening to dry out before dark. This will limit the chances of disease. If you use a soaker hose, you can water at night. Watering with a soaker hose at night is best as it limits the amount of water lost to evaporation and keeps the plants dry which limits the chances of disease. During dry periods you may need to water more often (every 4-5 days), and watering at night is important in water conservation during droughts.

Fertilize: Fertilize once when preparing the soil. You can also add a second optional side-dress fertilize application of 10-20-10 fertilizer when the plants begin to vine. Late varieties may need an additional side-dressing when the vines set fruit.

Harvesting: Depending on the variety of watermelon, it may take you a few tries to become familiar with the best stage for harvesting. One indicator is to look for yellowing on the underside of the watermelon where it sat on the ground.

Thumping the watermelon is a time honored tradition of testing for ripeness. Listen for duller sound of a ripe melon as opposed to a metallic sound. This technique will require some practice.

As watermelons age, they swell then split when over-ripe. You can look for the swelling as another indication of ripeness.

Pick watermelons early in the day on every other day early in the season and every day during peak season.  Be careful not to damage the vines when picking.

Culture Problems

  • Poor flavor and lack of sweetness is due to:
    • Poor fertility, low potassium, magnesium or boron (all of these are referred to as micro-nutrients due to the relatively low levels required by plants)
    • Cool temperatures
    • Loss of leaves from disease or picking
    • Picking unripe melons
  • Poor pollination (low yields)
    • Wet, cool weather
    • Lack of pollinators (bees, etc.)
    • Planting too close together which results in excessive vine growth
  • Split melons can be caused by heavy rain
  • Melons on the ground can develop rotten spots  or be damaged by bugs on the bottom. To prevent this you can place a layer of straw or sawdust under the melons.

Common Insect Problemsspotted_cucumber_beetle

Common Disease Problems