Issue: August 2003

Beat August Heat with Watermelons

August is a time for fishing, picnics and freshly harvested watermelon. Knowing when to pick a melon is the key to optimum flavor and sweetness. Many use the "thump" test, but there are more reliable methods.

First, use a calendar to track the average days from emergence to maturity for the variety being grown. Next, look for the corkscrew-shaped tendril on the stem that's attached to the melon. If it's withered and brown, the melon is probably ripe. Foliar diseases, however, can occasionally cause tendrils to wither prematurely.

The most reliable sign is the "couche" or "ground spot" where the watermelon touches the ground. A cream or pale yellow couche usually means the melon is ripe. White indicates immaturity and bright yellow means over maturity. The rind should also be dull rather than shiny. Watermelons should be cut off the vine, not pulled.

Melon sweetness comes from sugars like glucose, fructose and sucrose. Total sugar content will not increase after a melon is picked. That's why it's important to pick the melon at the right stage of maturity. Sugar content should be 10 percent or higher.

Sugar content, however, is only one factor that determines flavor in a watermelon. Various volatile compounds give each type of melon its unique taste and texture. Fibers in the flesh should melt in your mouth. Tough fibers make the flesh stringy while the absence of fibers makes it mealy.

To improve shelf life, store the watermelon at about 60 degrees F. Most watermelons can be stored two to three weeks. Off flavors and surface decay can occur at lower temperatures.

Watermelon varieties come in all sizes and shapes. Ice box and other smaller-fruited varieties like 'Sugar Baby' and 'New Hampshire Midget' tend to be earlier than larger fruited varieties like 'Desert King'. "Black" melons like 'Klondike' have a dark green rind, while "gray" melons like 'Charleston Gray' have a gray-green or mottled rind. 'Crimson Sweet' is a striped watermelon. 'Moon and Stars' has a dark green rind with yellow spots that look like a constellation of stars and planets. 'Golden Midget' has a yellow rind with salmon-pink flesh. Watermelon flesh can vary from dark red to orange-yellow, with seeds that are cream to black in color, or no seeds at all.

back to top

For more gardening information, visit New Mexico State University's Cooperative Extension Service publications world wide web site at

George W. Dickerson, Ph.D., is is a horticulturist with New Mexico State University's Cooperative Extension Service. New Mexico State University is an equal opportunity/affirmative action employer and educator.

Also Please join us on Southwest Yard & Garden, a weekly garden program made for gardeners in the Southwest on:
KNME-TV Albuquerque at 9:30 p.m. Saturdays,
KENW-TV Portales at 10 a.m. Saturdays,
and KRWG-TV Las Cruces at 11:30 a.m. Saturdays (repeated at 1 p.m. Thursdays.)