How to Grow Winter Squash Plants: The Complete Guide

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DLeonis/Getty Images
Botanical Name
Cucurbita maxima, C. pepo, C. moschata, C. argyrosperma
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Sun Exposure
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Planting, Growing, and Harvesting Winter Squash

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Growing winter squash requires some patience, but this garden vegetable is well worth the wait—and most varieties have a long shelf life after harvest. From butternut squash to acorn squash, learn how to plant, grow, harvest, and cure winter squash in your home garden!

About Winter Squash

Because winter squash requires a long growing season (generally from 75 to 100 frost-free days), the seeds are generally planted by late May in northern locations to early July in extremely southern states. See your local frost dates and length of growing season.

Winter squash are harvested in late summer or autumn, just before or after their fruits reach full maturity. Squash has a relatively long shelf life. Some varieties will keep through winter, hence the name winter squash. Varieties include acorn, butternut, delicata, Hubbard, pumpkin, and spaghetti.

Squashes and pumpkins are among the most thrilling vegetables you can grow. One minute, the seedlings are tentatively pushing through, and then, just a few weeks later, they’re great sprawling monsters with masses of leafy growth and plenty of fruits. I love the fact they’re so easy to grow, too—as long as you can keep up with their insatiable appetite, that is!

Despite the great diversity of squash, most commonly grown, cultivated varieties belong to one of three species:

  1. Cucurbita pepo
  2. C. moschata
  3. C. maxima

Over several generations, these plants have been cultivated to produce fruit in all kinds of shapes, colors, and flavors.

The Three Sisters

Squash is one of the three plants grown in the traditional Native American style called the Three Sisters, along with beans and corn. When grown together, the squash serves as a ground cover to prevent weeds from growing, beans provide natural fertilizer for all three plants, and corn provides a support system for the beans. Learn more about the Three Sisters.

Planting

Squash love a warm, sunny, and sheltered spot—ideal conditions for good pollination and proper fruit development. The plants are hungry feeders and need rich, fertile soil.

Plant squash in a location with full sun and lots of space for sprawling vines. Most full-size winter squash varieties need 50 to 100 square feet to spread. Soil must be well-fed and moist (not soggy), and well-draining. Mix aged manure and/or compost (about 50% native soil to organic matter) deep into the soil a couple of weeks before planting. 

Methods of Planting Squash

  • Direct-sow (i.e., plant seeds directly in the ground) when all danger of frost has passed and the soil is at least 60°F, preferably 70°F.  Squash is very sensitive to the cold.
  • If you have a short growing season, start seeds in peat pots 2 to 4 weeks before your last spring frost date. Squash seedlings do not always transplant well, so handle the roots gently.

Most garden stores and nurseries also sell ready-to-plant seedlings—handy if you only want to grow a few plants.

Set your plants out after all danger of frost has passed. Start to acclimatize them to outside conditions two weeks beforehand. Leave them out during the day for increasingly longer periods and then, from the second week, overnight in a sheltered position. Plant trailing varieties up to five feet (1.5m) apart and bush types about three feet (90cm) apart. Thoroughly water plants into position to settle the soil around the rootball.

How to Plant Squash

  • If you plan to grow only a few plants, use 2 to 3 tablespoons of a balanced (10-10-10) fertilizer for each hill. Scatter the fertilizer evenly over a 2-foot by 2-foot area. Work it into the top 3 to 4 inches of soil. Or, for a larger garden area, add 2 to 3 pounds of balanced fertilizer for each 100 square feet.
  • Sow seeds in level ground 1 inch deep with seeds 2 to 3 feet apart. Or, sow 3 to 4 seeds close together in small mounds (or hills; the soil is warmer off the ground) in rows 3 to 6 feet apart.
  • Consider planting a few squash seeds in midsummer to avoid problems from squash vine borers and other early-season pests and diseases.
  • The seeds should germinate in about a week with the right soil temperature (70ºF / 21°C or more). 
  • If necessary, use row covers or frame protection in cold climates for the first few weeks of spring. 
  • Use row covers to prevent insect problems early in the season. Remember to remove covers before flowering to allow pollination by insects.

See this helpful video on how to sow seeds.

Growing

  • Mulch to discourage weeds, retain moisture, and protect shallow roots. Mulch around plants with organic matter to help lock in valuable soil moisture and contribute additional nutrients.
  • Water thoroughly, frequently, and consistently, with at least 1 inch per week. Water at soil level and try to keep leaves and fruit dry. Dampness will make root rot and other diseases more likely. 
  • Keep plants well watered to encourage rapid growth. You can make watering easier by sinking six-inch (15cm) pots alongside plants. The pots will hold onto the water and deliver it through the drainage holes directly where it’s needed, at the roots.
  • When weeding around squash plants, do not over-cultivate, or the squash’s shallow roots may be damaged.

Thinning Seedlings

  • When seedlings in rows are 2 to 3 inches tall, thin to one plant every 18 to 36 inches by snipping off unwanted plants without disturbing the roots of the remaining ones.
  • When seedlings in hills are 2 to 3 inches tall, thin to 2 to 3 plants per hill by snipping off unwanted plants without disturbing the roots of the remaining ones

Fertilizing

  • When the first blooms appear, scratch about 2 tablespoons of all-purpose fertilizer around each hill. Or, if growing squash in rows, side-dress. This give plants a boost as they try to produce fruit or blooms. Do not let the fertilizer touch the plants. Water the plants after fertilizing.
  • Once vegetables or flowers start growing and producing buds, you can scratch a small amount of all-purpose organic fertilizer into the soil around the base of the plant and water in.

Flowering and Fruiting

  • Poor pollination can result in squash flowers that do not bear fruit, or that bear small fruit. Pollinator activity is reduced by any chemicals, poor weather at bloom time, and lack of habitat. To attract more bees, try placing a bee house in your garden or plant pollinator flowers nearby.
  • If your first flowers aren’t forming fruits, that’s normal! Squash plants have separate male and female flowers. Males appear first on long thin stalks. Female flowers follow with an immature fruit at the bottom. To fruit, pollen from male flowers must be transferred to the female flower by bees. Or, the gardener can help manually with a cotton swab or paintbrush. See our article on how to hand pollinate your squash blossoms for better yields.

Pruning

Although in many cases winter squash vines do not need pruning, there are instances where it might be necessary or desired. Pruning can reduce the number of squashes that grow, but helps the vine to put its energy into healthy growth and larger fruit.

  1. At any time, prune out dead, damaged, or diseased leaves or shoots. This applies to bush types, too.
  2. Whether your squash has a bush or vining habit, check for overcrowding and thin out a few lateral (non-main) stems or some lower (especially those touching the ground) or overlapping leaves to allow for better air circulation, which can help to prevent disease such as powdery mildew, reduce hiding areas for insect pests, and help pollinators to find the flowers. (A baby squash that has not been successfully pollinated will grow just a few inches and then rot.) Overcrowding can also cause weakened growth. Be sure, though, to leave enough leaves for the plant to make food for itself; do not prune more than 1/3 of the plant.
  3. Some vining varieties may take over the garden, growing as long as 10 to 20 feet. If you are short on space, a little pruning can help keep these vines under control. Or, you might consider growing them vertically or selecting a bush type, which does not have a sprawling habit.

Various gardeners have favorite methods for pruning their plants, while others prefer to essentially leave things alone, but here are some general guidelines: 

  • A vining winter squash plant has one or more main stems, each with secondary vines growing off it; in addition, tertiary vines may grow off the secondary vines. 
  • For vining squash types, many gardeners remove several nonfruiting secondary and all tertiary vines during the growing season. If you use this method, cut them back to their base, where they are attached to the main stem (leave about ½ to 1 inch of lateral stem, being careful not to injure the main stem). Again, do not remove more than 1/3 of the growth of the plant at any one time.
  • For fruiting secondary vines, wait until they are at least 10 or so feet long (depending on variety) and have about 3 to 5 fruit developing on them, then you can cut them back to 1 to 3 leaf nodes beyond the last fruit (toward the tip end). This will help the plant to focus on developing the remaining fruit on that vine rather than on growing the vine longer. 
  • Do not prune the main vines until toward the end of the season, at which point you might clip the growing tips off (as you did earlier to the secondary vines) to promote the ripening of existing fruit instead of more flowering. (Any flowers that form late in the season would produce fruit that might not mature in time before the end of the growing season.)

In general, the best time to prune is in the morning, when it is cooler, which allows the plant to recover before the end of the day. Alternatively, prune in the cool of early evening. 

When pruning, be sure to disinfect your pruning tools before each cut, to help prevent spreading disease. It helps to make sure that they are sharp, too. Learn how to sharpen your gardening tools.

Discard the pruned plant debris away from the plants. If diseased stems or leaves are removed, do not compost them, as some diseases may survive in the finished compost.

Harvesting

Winter squash and pumpkins are generally ready to be harvested in early- to mid-autumn, usually late September through October.

  • Unlike summer squash, which is harvested when tender and a bit immature, harvest winter squash when it is fully mature. The vine leaves die back and turn brown, the stems dry out and get tough, and the rind is deep in color and hard. If you can pierce the skin with your fingernail, it is not mature. 
  • Harvest on a dry day after the vines have died back.
  • Leave an inch or two of stem on winter squashes when harvesting them.
  • Cut the squash off the vine carefully with a sharp knife or pruners; do not tear, as you could break the fruit stem or the vines. 
  • Never carry the squash by their stem; if the stem breaks off, this exposes the skin to infection. 

Once you harvest, don’t forget to clean up the old squash vines to avoid disease! Add vines to the compost pile if you have one. They’ll break down, and you can work the compost into the soil before the next planting season.

How to Cure Winter Squash

Winter squash must be cured before storage. This process helps to dry off excess moisture and to harden the skin, sealing out fungi and bacteria, which allows the squash to be kept longer. 

Cut either side of the stem to leave a T-shaped stub. Avoid the temptation to use the stem as a handle, as it could detach from the fruit and serve as an entry point to rot. Move fruits to a warm, dry, and sunny spot to cure. 

If the weather is dry, just leave your squash on the vine and let them cure outside in the sunshine. If it’s wet or turning colder, bring the squash inside and put them somewhere warm and dry, such as a slatted greenhouse bench or a sunny window. 

Curing hardens the skin and is ready for storage. If it’s already turned cold and damp outside, cure fruits in a greenhouse or on a sunny windowsill. Winter squash and pumpkins will be stored for up to six months at room temperature.

How to Store Winter Squash

Before storing winter squash, dip it into or wash with a low-concentration bleach rinse (1/2 cup bleach to 5 cups water) to sanitize the skin and eliminate bacteria. Air-dry the fruit.

Store in a cool (40° to 50°F), dry, dark place with good circulation. Many varieties of squash will last most of the winter. Note: Acorn will not keep for more than a few weeks. Occasionally rotate and look for signs of rot. Remove any squash that shows signs of decay.

Try to save some seeds if you grow heirloom varieties (not hybrids) to plant next year. Wash and dry the seeds. Store in an airtight jar in a cool, dark place.

Gardening Products

Wit and Wisdom

  • The word “squash” derives from askutasquash, the Narragansett Native American word meaning “eaten raw or uncooked.”
  • Winter squash have been grown in North America for more than 5,000 years.
  • Presidents Washington and Jefferson grew squash in their gardens. Give it a try!
  • So-called squash bees—Peponapis and Xenoglassa—are excellent Cucurbita pollinators and especially so for butternut squash (and summer squash). Look for them among the flowers in the first few hours after sunrise.

Pests/Diseases

Squash bugs are generally considered the most troublesome pest. They need to be managed early. There are several organic approaches to control:

  • Handpick and scrape off those egg clusters early and as best you can
  • Spray neem on egg clusters and juvenile squash bugs
  • Grow young plants under row covers (uncover when flowering begins)
  • Delay squash planting until early summer as the natural predators of squash bugs become more numerous and active as summer progresses.

→ See our Squash Bug pest page for more information.

Squash Pests and Diseases
Pest/DiseaseTypeSymptomsControl/Prevention
AphidsInsectMisshapen/yellow leaves; distorted flowers/fruit; sticky “honeydew” (excrement); sooty, black moldGrow companion plants; knock off with water spray; apply insecticidal soap; put banana or orange peels around plants; wipe leaves with a 1 to 2 percent solution of dish soap (no additives) and water every 2 to 3 days for 2 weeks; add native plants to invite beneficial insects
Blossom-end rotDisorderDark, water-soaked spots on blossom end of fruit (opposite stem) may enlarge and become sunken and leatheryRemove affected fruit; plant at proper soil temperature; water deeply and evenly; use mulch; maintain proper soil pH (around 6.5) and nutrient levels; avoid excessive nitrogen; provide good drainage; prevent root damage
Cucumber beetlesInsectHoles in leaves/flowers; rasped fruit; plants stunted/die; can spread bacterial wilt (Bacterial wilt signs: wilting; plants die; ends of cut stems, when pressed together for 10 seconds and pulled apart, release stringy, white sap)Handpick; mulch heavily; use row covers; destroy plants infected with bacterial wilt
Cucumber mosaic virusVirusVaries with plant, but may include stunting, mottled green/yellow/white pattern or ringed spots on leaves/fruit; distorted leaf growth; warts on fruitDestroy infected plants; choose resistant varieties and certified virus-free seed; use row covers; disinfect tools; weed; control aphids; use mulch
Downy mildewFungusYellow, angular spots on upper leaf surfaces that turn brown; white/purple/gray cottony growth on leaf undersides only; distorted leaves; defoliationRemove plant debris; choose resistant varieties; ensure good air circulation; avoid overhead watering
Powdery mildewFungusTypically, white spots on upper leaf surfaces expand to flour-like coating over entire leaves; foliage may yellow/die; distortion/stunting of leaves/flowersDestroy infected leaves or plants; choose resistant varieties; plant in full sun, if possible; ensure good air circulation; spray plants with 1 teaspoon baking soda dissolved in 1 quart water; destroy crop residue
Squash bugsInsectMany small, yellow/brown/black spots on leaves; wilt; scarred fruitHandpick; crush yellow/bronze egg clusters on leaf undersides; lay boards on soil and check for pests underneath each morning; remove plant debris; use row covers; rotate crops
Squash vine borersInsectVines wilt suddenly; plants die; mushy area and/or green to orange-yellow, sawdust-like excrement on/near base of plant stemIf detected early, slit infested stem lengthwise halfway to remove borer(s), then bury the cut in moist soil to encourage rooting; wrap seedling stems in aluminum foil collar; catch moths with yellow sticky traps; use row covers if no pests previously, but uncover before flowering; destroy crop residue; rotate crops
StinkbugsInsectYellow/white blotches on leaves; scarred, dimpled, or distorted fruit; shriveled seeds; eggs, often keg-shape, in clusters on leaf undersidesDestroy crop residue; handpick (bugs emit odor, wear gloves); destroy eggs; spray nymphs with insecticidal soap; use row covers; weed; till soil in fall

Cooking Notes

  • Winter squash is often baked in casseroles or on its own. Cook all types of squash only until tender to keep the nutritional content.
  • Mmmm, Pumpkin Pie! See our collection of Best Pumpkin Recipes!
  • Winter squash is a good source of vitamin A and has fair amounts of vitamin C. The darker the flesh, the more beta-carotene the squash has to offer. Learn more about winter squash’s health benefits
  • One cup of cubed winter squash contains about 80 calories, virtually no fat, and very little sodium.
About The Author

Catherine Boeckmann

Catherine Boeckmann loves nature, stargazing, and gardening so it’s not surprising that she and The Old Farmer’s Almanac found each other. She leads digital content for the Almanac website, and is also a certified master gardener in the state of Indiana. Read More from Catherine Boeckmann