By May, all melons are growing quickly, spreading their long vines throughout the garden, flowering, and hopefully fruit set is well underway. The first flush of flowers in melons is dominated by female flowers, known by the tiny fruit at the base. Without pollination, the fruit may grow a bit then fall off. To increase fruit set, hand-pollinate daily, as early in the day as possible. Pick a male flower and rub the pollen on a female flower or two. Flowers only last a day, so don't worry about picking them.
May is also when the weather begins to heat up significantly. Provide shade to melon plants to ensure that they do not wilt dramatically, the leaves don't burn, and the fruit is protected. Well grown, shaded melons continue to produce for a long time through the summer months, but May is the time to get them prepared.
Melons of all types are heavy feeders. Grow in rich soil and mulch heavily through the warm months. You can amend your soil with organic material such as compost, well-seasoned manure, fish emulsion, or Miracle-Gro® Organic Choice® Garden Soil. Feed your melon plants with balanced fertilizer regularly through the growing season. Miracle-Gro® Shake 'n Feed Tomato, Fruits & Vegetables Continous Release Plant Food Plus Calcium feeds your plants for up to 3 months.
In the low desert, melons can be planted again in July or August for a fall crop. This traditional planting, to coordinate with the monsoon rains, is done just about the time the spring crop is spent.
Knowing when to harvest melons can be tricky and the various types have different tests. Muskmelons, which Americans call cantaloupe, are the netted melons. Test for ripeness by pressing gently on the blossom end, ripe melons have some give, unripe ones none at all. Fruit should smell like melon and slip from the stem with gentle pressure. True cantaloupe has smooth skin, deep or at least obvious furrows, and fruit does not release or slip from the vine when ripe. Pushing on the blossom end is the best test for ripeness in these.
Watermelon is generally ripe when the fruit has quit growing, the skin is dull not shiny, the small spot that touches the ground is yellow instead of white, and the tendrils on the stem are withered. If you strike the plant with the flat of your hand, it should give a deep thump.
Melons are native to northern Africa and western Asia but have been in cultivation and objects of trade for thousands of years. Therefore, the variety is enormous, and finding ones that do well in the desert Southwest is the result of experimentation and shrewd selection. Varieties from the Middle East, like Ogen, or those long grown in the Southwest like San Juan or O'odham yellow watermelon are sure winners. Also look for varieties from hot regions or those with 80 days or less to maturity.