How to Grow Winter Squash

Squash Spaghetti

Spaghetti Squash

Winter squash is a frost-tender, warm-season annual. Winter squash is grown to maturity on the vine, until the skin is very hard (unlike summer squash which is harvested while the skin is still tender). Popular winter squashes include hubbard, butternut, acorn, delicious, banana, Turk’s turban, cushaw, and spaghetti squash.

Sow winter squash seeds in the garden–or set out seedlings started indoors–only after the soil has warmed to at least 60°F, usually no sooner than 3 weeks after the last frost in spring. Winter squashes grow best in air temperatures ranging from 50° to 90°F; established fruit will ripen in temperatures as high as 100°F but flowers will drop in high temperatures. Winter squash require 60 to 110 days to reach  harvest.

Description. Squashes are a large group within the cucumber family, Cucurbita, and include winter squashes, summer squashes and pumpkins. Winter squashes are eaten after they have matured and their skins have thickened and hardened. Some winter squashes grow fruit as long as 30 inches. Squashes have large, broad leaves; 4 to 6 stems or vines grow from a central root. Some winter squashes are sprawling; others are bush like. Fruits vary in shape from round, to oblong, to cylindrical to turban shaped. Separate male and female flowers appear on the same plant. Winter squashes have a distinct seed cavity unlike summer squashes.

Yield. Grow 1 or 2 summer squash plants per household member.

Site. Plant squash in full sun. Grow squash in loose, well-drained soil rich in organic matter. Prepare planting beds in advance working in plenty of aged compost. Add aged manure to planting beds the autumn before growing squash. Squash prefers a soil pH of 5.5 to 6.8. Winter squashes will sprawl and require ample space; if space is tight train them over small A-frame or up a trellis as tall as 5 to 8 feet.

Planting time. Winter squashes are frost-tender, warm-season annuals. Sow squash seeds in the garden–or set out seedlings started indoors–only after the soil has warmed to at least 60°F, usually no sooner than 3 weeks after the last frost in spring. Start squashes indoors as early as 4 weeks before the last average frost date in spring. Sow seed indoors in biodegradable peat or paper pots that can be set directly in the garden so as not to disturb or shock plant roots. Winter squashes grow best in air temperatures ranging from 50° to 90°F; established fruit will ripen in temperatures as high as 100°F but flowers will drop in high temperatures. Winter squashes require 60 to 110 days to reach harvest.

Planting and spacing. Sow squash seeds 2 to 3 inches deep. Sow squash in hills or inverted hills, 4 to 5 seeds set 3 to 4 inches apart; thin to the two strongest seedlings. Space hills 6 to 8 feet apart. In rows, plant 2 squash seed 10 inches apart in rows 3 to 5 feet apart; thin successful seedlings in rows to 3 feet apart. Thin seedlings by cutting off weak seedlings at soil level with scissors so as not to disturb fragile roots. Hills or mounds should be 6 to 12 inches tall and 20 inches across. This will allow plants to run down the hill and away from the main stem. Inverted hills–which are used to retain moisture in dry regions–can be made by removing an inch of soil from an area about 20 inches across, using the soil to form a ring or circle. Plant 4 or 5 seeds in each inverted hill. Winter squash can be caged or trained up a fence or trellis. Set supports in place at the time of planting.

Water and feeding. Squash grow best in soil that is kept evenly moist. Squashes require a lot of water in hot weather. Plants may wilt on hot days as they use water faster than the roots can supply. As long as water is regular and deeply applied, wilted plants will liven up as the day gets cooler. Squash that is wilted in the morning needs immediate water. Add aged compost to planting beds before planting and side dress squash with aged compost at midseason. Side dress squash with compost tea every 2 to 3 weeks during the growing season. Avoid feeding squash with a high nitrogen fertilizer, 5-10-10 is best.

Companion plants. Nasturtiums, bush peas, beans. Avoid planting summer squashes in the shadows of taller plants.

Care. Squash have separate male and female flowers. The first flowers to appear are male flowers which will not produce fruit. Female flowers appear slightly later and are pollinated by the male flowers commonly with the help of insects. If pollination is slow or does not occur, use a soft-bristled brush to dust inside a male flower then carefully dust the inside of a female flower (a female flower will have an immature fruit on its stem, a male won’t).

Once fruits form set each one on a wooden plank so that it does not have direct contact with the soil; this will allow squashes to mature with less exposure to insects.

Container growing. Bush-type winter squash can be grown in containers but the season is long. Sow 2 or 3 seeds in the center of a 10-inch container; thin to the strongest seedlings once plants are 3 to 4 inches tall. Extend the growing season by planting early and moving pots indoors when frost threatens. Set a cage or trellis in place to save space.

Pests. Squash can be attacked by squash bugs, squash borers, and cucumber beetles. Hand pick or hose away beetles. A small hole in the stem or unexplained wilting may indicate the presence of borers. Slit the stem, remove the borers, and dispose of them. Cover the slit stem with soil to encourage root development from that point.

Squash borers or bacterial wilt can cause squash plants to suddenly wilt and die just as they begin to produce. Bacterial wilt can be spread to squash by cucumber beetles; handpick and destroy cucumber beetles.

Complete run down on squash pests and diseases: click here.

Diseases. Squashes are susceptible to bacterial wilt, mosaic virus, and mildew. Plant disease-resistant varieties. Keep the garden clean and free of debris where diseases and pests may harbor. Water at the base of plants to keep water off the foliage, and do not handle plants when they are wet to avoid the spread of fungal spores. Remove and destroy infected plants before they spread disease to healthy plants.

Powdery mildew, a fungus disease, will cause leaves to turn a gray-white color late in the season. Proper spacing and increased air circulation will help reduce this problem.

Mosaic virus can cause squash plants to become mottled yellow and stunted. Mosaic virus is spread by aphids. Control aphids and remove affected plants.

Blossom end rot will cause squash fruit to rot from the blossom end. Blossom end rot is caused by fluctuations in soil moisture. Water evenly and regularly and mulch around plants to conserve soil moisture.

Harvest. Winter squashes are ready for harvest 60 to 110 days from sowing when rinds are full color and firm (some acorn squash may be green and have semi-hard rinds). Winter squashes should be allowed to mature fully on the vine. If the rind cannot be dented with your thumbnail, it is ready for harvest. Complete the harvest before the first hard frost. Stems and vines will be hard and dry at harvest time. Cut squash from the vine leaving 2 to 3 inches of stem above the fruit; this will allow the squash to store longer. Use knife, pruning shears, or lopper to cut thick stems. Keep pruners clean so as not to spread disease to other plants.

Turban squash

Turban squash

Winter SquashVarieties.

Acorn: Autumn Queen (71 day); Bush Table Queen (82 days); Carnival; Cream of the Crop; Ebony Acorn (85 days); Gill’s Golden Pippin (85 days); Heat of Gold; Jade; Table Ace (78 days); Table Gold (90 days); Table King (80 days); Table Queen (85 days); Tay Belle (70 days); Tubby Acorn.

Banana: Pink Banana Jumbo (105 days); Blue Banana (105-120 days).

Buttercup: Bush Buttercup (88-100 days); Emerald (90 days)

Butternut: Early Butternut (75 days); Harris Butternut; Hercules (95 days); Nicklow’s Delight; Ultra Neck Pumpkin; Waltham Butternut (85-110 days); Zenith Butternut (85-120 days).

Delicious: Golden Delicious (100 days).

Hubbard: Baby Blue Hubbard (90 days); Blue Hubbard (100-120 days); Kindred (100 days); Little Gem (80 days); New England Blue Hubbard (120 days); Sweet Meat; Warted Chicago Hubbard (110 days).

Spaghetti: Pasta (90 days); Pasta Spaghetti; Stripetti (95 days); Tivoli Spaghetti (100 days); Vegetable Spaghetti (90-110 days).

Sweet potato squash: Delicata (92 days); Sugar Loaf (105 days); Sweet Dumpling (100 days); Thelma Sander’ Sweet Potato.

Turban: Ambercup; Autumn Cup; Bitterroot; Burgess Buttercup; Buttercup; Churimen Abobora; Emerald Bush (90 days); Honey Delight (95-110 days); Sweet Mama (85 days); Turk’s Turban (110 days).

Others: Doe; Flat White Boer; Futtsu Early Black; Gold Cushaw (115 days); Gold Nugget (95 days); Hopi Pale Grey; Lower Salmon River; Mayo Blusher; Red Kuri (95 days); Silver Bell; Sweet Meat; Tahitian (85-220 days).

Storing and preserving. Winter squashes require curing before storing. Cure squashes in the sun for a week or more or place them in a dark, humid place for 10 days at 80° to 85°F. After curing store winter squash at 50° to 60°F in a dry, dark place. Winter squash will keep for 5 to 6 months. Winter squash with a soft skin will likely rot in storage; these squash should be cooked right away. Do not wash squashes until you are ready to use them. Cooked squash can be frozen, canned, pickled or dried.

Common name. Acorn, banana, buttercup, butternut, cushaw, delicious, hubbard, spaghetti, Turk’s turban

Botanical name. Cucurbita maxima and Cucurbita moschata

Origin. American tropics