Posted on: Friday, July 1, 2005
HAWAI'I GARDENS
Nothing says summer like sweet watermelon
By Jari Sugano
Watermelons are the perfect crop for Hawai'i's long summer days. Watermelons grow best on well-drained, sandy soils with pH levels of 5.5-6.8 (slight acidity).
Gannett library photo Variety is perhaps the most important factor when planting watermelons in Hawai'i. Varieties suitable for Hawaii's gardens include Crimson Sweet, Glory, Wide Ranger and Sweet Carnival.
Apply 2 to 3 buckets of well-rotted manure or decomposed organic matter per planting hole. Apply 10-20-20 fertilizer at 1ý pounds per 100 square feet — half at planting time and other half a month later. Additional fertilizer applications should be based on crop monitoring. During fruit development, potassium and adequate moisture is needed to achieve good fruit set and top-quality watermelons.
Watermelons are highly dependent on honey bees for pollination. Avoid disrupting honey-bee activity during the morning hours with pest management sprays and overhead irrigation. Fusarium, pythium, powdery mildew, gummy-stem blight, anthracnose and damping off are serious diseases that affect watermelon production.
Avoid watering plants late in the evening to minimize foliar diseases. Thrips, aphids, whiteflies, melon flies and leaf miners are insect pest that also reduce yields. Consult the UH College of Tropical Agriculture and Human Resources' Master Gardener Program at 453-6055 for the latest pest-control techniques.
Melons should not be watered heavily when fruits are maturing. As harvest approaches, reduce irrigation slightly to increase sugar levels and minimize hollow centers.
Sugar levels do not increase after harvest. Therefore, it is important to harvest fruits at their peak. There are several ways to determine if a watermelon is ready.
Staking is one of the best ways to predict ripening. That involves placing a dated marker near each fruit when it is 2 to 3 inches in diameter. Depending on variety, watermelons are harvested about 28-30 days after staking. Experienced growers use the change in color of the rind, a dried tendril on the vine nearest the fruit, or the thumping technique. Thumping on a ripe melon will produce a dull, low-pitched "plunk" sound while an unripe fruit produces a metallic "plank" sound. (Obviously, this method requires practice.)
Fruits should be cut from the vines and handled with care.
Faced with choosing between Mainland and Hawai'i-grown watermelons this summer? Buy local. Buy supah-fresh!
Jari Sugano is an extension agent with the University of Hawai'i-Manoa College of Tropical Agriculture and Human Resources. Reach her at suganoj@ctahr.hawaii.edu.
Plants can be direct seeded or transplanted into mounds 3 to 8 feet apart, in rows 10 to 12 feet apart. For home gardens, sow 2 to 3 plants per mound. Raise planting beds to increase drainage, and mulch with plastic sheeting to retain soil moisture and control weeds.
Increasingly popular with Hawai'i growers and consumers are the miniature varieties that fit more conveniently into crowded fridges.
