Winter squash is so-named because unlike summer squash, which has a soft skin and should be enjoyed right away, the hard-skinned fruit of winter squash can be cured and then stored for several months. Butternut, spaghetti and acorn squash are classic examples, and pumpkins too are a cultivar of winter squash. If you want to grow winter squash in your garden, here’s everything you need to know.
You can also download my How Do I Grow Winter Squash one-sheet and keep the free resource handy for your reference.
There are so many options when cooking with winter squash, and nearly all of them fall into the category of comfort food. The fruit of winter squash can be roasted or stuffed, and some varieties make a great base for soup or pie. They can also be diced to serve as a side or mixed with pasta for an entree, and can even go in salad and casseroles. Well before the fruit are mature, winter squash flowers can be picked and served fried or baked.
Where, Where and How to Plant Winter Squash
Winter squash can be direct-sown, but if you live in a northern climate it’s a good idea to start seeds indoors three to four weeks before the last frost date for your area. Plant seeds 1 inch deep, with two seeds per pot, in sterile seed starting mix. The seeds will germinate 7–10 days later if planted in soil that’s kept between 70° and 95°. A seedling heat mat is a useful tool to reach the optimal temperature range.
Using a grow light will ensure seedlings get the light they require and will prevent the plants from stretching out in search of sunlight. Running a fan gently over seedlings will reduce damping off disease, which can be fatal. Also, be sure to harden off seedlings before they are planted out. Hardening off is the process of gradually introducing plants to the outdoor environment and the intensity of the sun for a week or so. Put seedlings out for just a half-hour on the first day and add more time outdoors each day until they are ready to handle a full day’s worth of sunlight.
Winter squash is a heat-loving plant, so wait until the risk of spring frost is long gone before planting seeds or seedlings outdoors. Winter squash have long, sprawling vines, so plan ahead by giving plants several feet of space to grow in all directions, or plant them near a trellis or arbor that the vines can grow up. Livestock panels are great for this purpose.
There are bush and semi-bush varieties to look for if you are limited on space.
When planting your own seedlings or seedlings from a nursery, be careful not to damage the sensitive roots. If direct sowing, sow into hills of soil. After the seeds have sprouted, thin to two or three plants per hill.
Winter squash will grow best in soil with a pH that’s in the range of 6.0-6.5. The planting location should receive full sun — that’s 6–8 hours of direct sunlight daily — and the soil should be very fertile and well draining.
To keep pests from laying their eggs on squash plants, you can cover the seedlings with floating row cover. This goes a long way toward reducing pest issues, but the row cover will need to be removed once the plants begin to flower so pollinators can reach the blossoms — or you can manually pollinate the plants yourself.
Hand-pollinating starts with identifying a female flower to pollinate. It will have a small embryonic fruit between the flower and the plant stem. This embryonic fruit needs to be pollinated before it will grow and mature. Next, pick a male flower — you can tell it is male because there will be nothing between the flower and the stem — and peel back the petals to reveal the pollen-covered anther. Brush the anther around the stigma of the female flower, and then close the flower with a clothespin to allow the pollination process to complete. Another method is to take a small painter’s brush and dab it onto the anther to collect some of the pollen then lightly “paint” the pollen onto the stigma of the female flower.
Types and Varieties of Winter Squash
The range of winter squash is quite wide. The many different varieties can be of the species Cucurbita moschata, Cucurbita pepo, Cucurbita maxima or Cucurbita argyrosperma. What varieties to pick out for your garden depends on your goals: Do you want ingredients for delicious recipes, or is your desire to grow giant ornamental pumpkins?
Acorn squash (Cucurbita pepo) are shaped like acorns with deep ridges and weigh up to 2 pounds. Most are green, orange or a combination of the two, though there are modern varieties in yellow and white. On the inside, the flesh is orange, sweet and nutty. Acorn squash are faster to grow than many other winter squash varieties. Days-to-harvest is generally 85 days. Bush Table Queen is a bush-type for small-space and container gardens. Autumn Delight is a dark green semi bush hybrid, and Mashed Potatoes has ivory white fruit on productive, compact vines.
Buttercup squash (Cucurbita maxima) is round and flat with dark green skin and orange, rich, sweet flesh. The fruit have a gray “button” at their base and weigh 3–5 pounds
Butternut squash (Cucurbita moschata) was created by breeding gooseneck squash and Hubbard squash, and is one of the most popular winter squash types there is. Its dense vines resist the dreaded squash vine borer, and the fruit have a sweet, nutty flavor. The 3-pound, light tan, bulb-shaped fruit is used in pumpkin pie filling and countless other recipes. Days to harvest is generally 110–120 days, but be on the lookout for newer varieties that are quicker to mature. Butterbush is an heirloom bush-type butternut squash. Puritan is a popular vining hybrid that does not set seed. Butterbaby is a hybrid with short vines that grows mini, approximately 5-inch fruit.
Delicata (Cucurbita pepo) has long, cream-colored fruit with green stripes, sweet flesh and a tender, edible rind. The fruit generally weigh up to 2 pounds and 9 inches long, but a variety like jester is shorter, rounder and only grows to 1.5 pounds.
Galeux d’Eysines squash (Cucurbita maxima) is a French variety with fruit that are round and flat, salmon-peach colored, and covered with “warts.” It’s a favorite both for decorating and eating. The fruit are 10–20 pounds each.
Hubbard squash (Cucurbita maxima) varieties come in many shapes and colors and have interesting, sometimes bumpy textures. Blue hubbard squash, for instance, has pale blue fruit that weigh between 25 and 40 pounds, while the warted green hubbard grows to be only 8–12 pounds. Red Kuri has red teardrop-shaped fruit that are no larger than 5 pounds. North Georgia Candy Roaster has long, bent, bright orange 8–15-pound fruit with a green tip. Hubbard squash is very attractive to squash vine borers to it is sometimes planted as a trap crop.
Kabocha squash (Cucurbita maxima) originates from Japan and tastes like a mix of sweet potato and pumpkin. The fruit come in many colors — dark green, light green, pale blue, deep red, etc. — and can be striped. Winter Sweet is renowned for dark gray, mottled fruit that stores for an extra long time. The fruits weigh 4–5 pounds. Cha Cha is green with pale stripes on the ribbing and flaky, sweet orange flesh. The fruit are 4–5 pounds. Sunshine has smaller fruit, from 3–5 pounds, that are deep scarlet.
Pumpkin is a term that applies to all different species of winter squash with fruit that are round, smooth or slightly ribbed, usually orange, and often grown for decoration rather than culinary uses. What one seed company calls a pumpkin the next might call a squash, and vice-versa. For ornamentals and Jack-o’-lanterns, you can pick out pumpkin varieties that are bred to grow as immense as possible, or something a much better size for a porch. For pumpkin pie, in general, look for a variety that’s of the Cucurbita moschata species.
Spaghetti squash (Cucurbita pepo) is named for its unique flesh. It’s yellow and, when scooped out, resembles spaghetti. It can actually be served with tomato sauce just like pasta. Traditional spaghetti squash weigh about 3–5 pounds, but the lighter Angel Hair is no more than 2 pounds, and Pinnacle is a semi-bush with fruit weighing in at 3 pounds.
Sweet Meat (Cucurbita maxima) is a Northwest favorite that originated in Oregon. The heirloom fruit are 10–20 pounds with gray skin and orange flesh that is sweet and flavorful.
Watering Winter Squash
Squash plants require an inch of water a week, or up to two inches during the hottest stretch of summer. If it is rained any less than an inch in a week, make up the difference with supplemental watering.
Avoid watering from overhead. Apply water at the base of plants, under the foliage, so the leaves remain dry. A layer of organic mulch over the soil and around the vines will retain moisture in the soil and has the added benefits of suppressing weeds and reducing the occurrence of plant diseases.
Fertilizing Winter Squash
Squash is a heavy feeder. Get plants off to a good start by generously amending the soil with manure prior to planting. Side dressing established plants with compost will give them an extra boost.
For an additional boost to squash plants, use a fertilizer with an NPK that has a lower first number than second number. The “N” stands for nitrogen, and that helps with vine growth, while the “P” stands for phosphorus, which helps with fruit productions. Fertilizer containing less nitrogen than phosphates is best because an abundance of nitrogen will result in vigorous vines with less fruit set.
Always follow the manufacturer’s instructions when applying fertilizer. More does not equal better and can actually be detrimental. Organic fertilizers are slow-release, while synthetic fertilizers give a quick jolt of nutrients and pose the risk of nutrient burn.
Winter Squash Pests & Diseases
Squash vine borer is a squash pest that destroys squash plants from the inside. The life cycle starts when an adult squash vine borer, a moth, lays eggs at the base of a plant on the stem or under the lower leaves. When larvae hatch from the eggs, they bore their way into the plant and eat the tissue inside stems and vines. The best way to control this pest is to prevent egg-laying. A physical barrier of floating row cover will keep the adult off the plants. Just be sure to remove the cover when the plant blooms so pollinators can reach the flowers. Aluminum foil wrapped around the first few inches of the stems is another effective barrier. If your plants already have vine borers inside, you can inject liquid Bt, a biological control, into the vines. For more information on managing this pest, read Squash Vine Borer Prevention & Control, my comprehensive guide.
Squash bugs are cucurbit pests that damage plant foliage as they feed and cause even more problems by transmitting cucurbit yellow vine disease. They use their mouthparts to suck sap right out of leaves, causing the leaves to wilt, dry up and die. The adults usually lay their bronze-brown and oval-shaped eggs on the underside of leaves between the veins. The nymphs hatch 10 days later and the bugs mature after another month or so. The adults are five-eighths of an inch long with flat, dark gray, almost black bodies, and six legs. Row cover, hand-picking and insecticidal soap are a few control methods. For more information on managing this pest, read Squash Bug Prevention & Control, my comprehensive guide.
Squash beetles are a pest found in the Eastern United States. They are orange-red with black dots and often confused for beneficial lady beetles. In fact, they are sometimes called squash lady beetles. Both the larvae and adults feed on squash leaves, and the adults will also feed on fruit. Floating row cover can stop the adults from landing on leaves to lay their yellow eggs. Hand-picking of eggs and adults will effectively control this pest.
Cucumber beetles, which have both spotted and striped species, are common cucurbit pests that sometimes target squash. They chew holes in leaves and pass a pathogen that causes bacterial wilt that can kill your plant in a matter of days. Hand-pick beetles as you find them. If a cucumber beetle problem arose one year, chances are it will happen again the following year. Practice crop rotation so the cucumber beetle population does not build up in your garden.
Powdery mildew and downy mildew are fungal diseases that affect squash leaves and vines. Plants severely affected by powdery mildew appear coated in white powder, and downy mildew causes yellow spots. To prevent mildew, plant seeds or seedlings in full sun with adequate space so air can circulate between the vines of mature plants. Avoid overhead watering because humidity around leaves creates a very welcoming environment for fungal spores. Water underneath leaves and vines, possibly with a drip irrigation system or soaker hoses. Read my comprehensive guide Powdery Mildew Prevention & Control for more information.
Harvesting Winter Squash
You can tell when winter squash is ready by trying to pierce the rind with your fingernail. If you can’t, it’s ready.
Another sign of readiness is when the stems begin to crack and dry. Cut the fruit from the vine with pruners, making sure to leave an inch of stem attached to the squash. That will help with storage, or you can enjoy it right away.
Winter squash should be left on the vine for as long as you can get away with — until just before the first frost of fall. It’s important that winter squash are fully mature when picked because immature squash will not store well.
When bringing harvested squash indoors, don’t wash them. Just wipe them off with a slightly damp cloth to get the dirt off, and then pat dry. Allow squash to cure for two weeks in a warm space to toughen up the skin, then store in a cool space below 60° and out of direct sunlight. Enjoy your harvest all winter long!
What are your secrets to grow winter squash successfully? Let us know in the comments below.
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Links & Resources
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joegardener Online Gardening Academy™: Three popular courses on gardening fundamentals; managing pests, diseases & weeds; and seed starting!
joegardener Online Gardening Academy Beginning Gardener Fundamentals: Essential principles to know to create a thriving garden.
joegardener Online Gardening Academy Growing Epic Tomatoes: Tomato expert Craig LeHoullier joins me in leading this course on how to grow healthier, productive tomato plants and how to overcome tomato-growing challenges.
joegardener Online Gardening Academy Perfect Soil Recipe Master Class: Learn how to create the perfect soil environment for thriving plants.
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