Growing Pumpkins

Pumpkins are members of the cucurbit family, which also includes cucumbers, squash, gourds and melons. More than a billion pounds of pumpkins are produced annually in the United States, primarily for the fall season. Numerous varieties, shapes, colors and sizes of pumpkins exist for fall decorating and carving as well as pie types suitable for baking.

Production

Pumpkins are easy for home gardeners to grow and generally require minimal labor compared to many other garden crops. They are warm season crops and can easily be injured by frost. If seeding directly, the soil temperature should be at least 65 F for the seed to germinate. Since the timing of the fall market is important, the maturity date of the specific variety is the main consideration for when to plant. Most varieties mature in 90 to 110 days, so planting in June and early July is appropriate. Pumpkin plants generally produce extensive vines so ample space is needed.

Soil

Ideal pH for pumpkins is 6.0 to 6.8. Some West Virginia soils are acidic, so lime may be needed to increase soil pH. You must soil test to be certain. Fertile, loose, well-drained soil high in organic matter is best for direct seeding or transplanting. No-till production can be used to maintain soil health, control weed emergence and decrease soil erosion. It is important that the soil drains so that there is no standing water left after rain, as this might spread disease or rot pumpkins. Pumpkins contain a high percentage of water, however, so irrigation may be required to ensure an adequate water supply to the plant. Drought stress during flowering or at fruit set can decrease yield.

Fertilization

Soil also should be tested to determine nutrient levels. Nitrogen is important for green, leafy growth and vining; pumpkins will likely need 50 to 100 pounds of actual nitrogen (equivalent to 150 to 300 pounds of 34-0-0 fertilizer) over the season. Half can be applied at planting with phosphorus and potassium and the other half can be applied when the vines begin to run, about 30 days later. Phosphorus is needed for root development, and both phosphorus and potassium are needed for fruit production. If the soil test indicates both are needed, a complete fertilizer, such as 19-19-19, can be used to supply nitrogen, phosphorus and potassium.

Planting

Pumpkins can be seeded directly in the field when soil temperature exceeds 65 F consistently. Typically, a few seeds are planted in a hill and the hill is thinned to one or two plants after establishment. Two to 8 pounds of seed will be needed per acre depending upon the variety. Transplants can be used if preferred.

Spacing between plants and rows depends upon the mature size of the fruit and vine. Pumpkins that vine should be spaced in rows 10 feet apart with large pumpkins requiring 5 feet between plants and small pumpkins needing 4 to 5 feet between plants. There also are compact, bush-type (restricted vine) pumpkins; these varieties can tolerate 8 feet between rows and 2 feet between plants.

Weeds

Weeds decrease air circulation, increase disease risk and make harvest difficult. Weeds can be decreased before planting by killing the cover crop in a no-till system. If cultivating the field for traditional production, till the field several times to break the weed life cycle and again between the rows before pumpkins start vining. Avoiding broadcast fertilizer applications also can help prevent excessive weed growth. Proper fertilization and irrigation to establish a heathy pumpkin crop can increase the chance of pumpkins outcompeting weeds.

Problems

Adequate water is essential, especially during flowering and fruit set. Early signs of drought stress include wilting and dropping blossoms. Pumpkins have separate male and female flowers on each plant. Male flowers open first and are short-lived. Efficient and timely transfer of pollen from male flowers to female flowers by bees is essential for fruit production, thus the health of the flowers and bees is essential for pollination, fruit set and maximum production. Bees are often harmed by pesticides applied to pumpkins, weeds or blooming plants in the area. Few fruit, small fruit and misshapen fruit are signs of inadequate pollination.

Harvest

Pumpkins should be harvested before the first hard freeze in fall. Size, weight and physical characteristics of the mature (ripe) pumpkin depend upon the variety grown. In general, they can be harvested when the stem and rind begin to harden. Many types experience color changes at this point, and they may have a round spot color change as well. A few inches of the stem should be left on the pumpkin and stems should be handled carefully to prevent damage. Pumpkins can be cut from the vine with sharp pruners and left in the field to cure to allow the rind to harden. Pumpkins that are harvested a little early for the seasonal market or pie varieties can be stored in a dry and reasonably cool area (50 to 55 F) to extend their storage life by several weeks. High humidity and extreme temperatures will damage pumpkins quickly.

Insects and Diseases

Nutrition

While most pumpkins are grown for ornamental use, if consumed, pumpkins are an excellent source of the antioxidant beta-carotene, which is converted to vitamin A in the body. Beta-carotene is believed to provide protection against heart disease, some types of cancer and some effects of aging. Pumpkin also contains a moderate amount of fiber and potassium.

According to USDA nutritional facts, 1 cup of plain, cubed, raw pumpkin contains 30 calories and 1 cup of cooked, mashed pumpkin contains 115 calories. Roasted pumpkin seeds also can be a healthy snack with 1 ounce providing 8.5 grams of protein and 1.8 grams of fiber. However, oil and other additions increase calories depending upon the recipe used.

Authors: Lewis Jett, WVU Extension Specialist – Commercial Horticulture, & Jodi Richmond, WVU Extension Agent – Mercer County

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