How to Grow: Winter Squash

It’s tough to pigeon-hole winter squash (Cucurbita maxima, C. pepo, and C. moschata). There are so many shapes, colors, and sizes, they can turn your garden into a cornucopia of fruits. They take all season to produce and most take up lots of space. But if you have the room,

Butternut winter squash fruit

they’re worth growing. I love going into my basement in December and pulling out a buttercup squash from storage to eat for dinner. The flesh is sweet and flavor satisfying on a cold winter day.

Pumpkins are a type of winter squash, but they’re so special I talk about them in their own section. This is where I’ll talk about buttercup, butternut, acorn, delicata, and spaghetti winter squashes. If it’s hard to know which to grow, buy a few from the local farmer’s market to decide which you like best.

When to Plant

Winter squash seeds or transplants should be planted after all danger of frost has passed in your area. That’s usually sometime in May or June. Start seedlings indoors 4 weeks before transplanting into the garden.

Where to Plant

Most winter squash varieties need room to vine or “run”. I like planting on the edge of the garden and letting plants run into the lawn area. It saves space in the garden and reduces the amount of mowing I do. Winter squash need full sun, so don’t plant where they’ll get shaded from taller crops. Like pumpkins, summer and winter squash plants have separate male and female flowers, so plant flowers nearby to attract pollinating insects or do a little hand pollinating yourself (see cucumbers).

How to Plant

Amend the soil with compost before planting. To get a jump on the season, lay down black plastic over the bed 2 weeks prior to planting to preheat the soil. The plastic also acts as a weed barrier and conserves soil moisture. Poke holes in the plastic every 3 feet and plant three seeds or one seedling per hole. Space rows 5 feet apart. After germinating, thin the seedlings to the strongest plant per hole.

Care and Maintenance

Winter squash need a consistent supply of water and fertility to vine and set fruits. Add 1- to 2-inches of water per week during the growing season. Add a small handful of an organic fertilizer, such as 5-5-5, per plant at transplanting or seeding and again when the vines begin to run. Keep beds well weeded until the vines fill the area and can shade out any young weeds.

To encourage fruits to mature before frost, snip off the vines, flowers, and any young fruits in fall. The flowers and young fruits are great tasting sauteed. These won’t have enough time to mature before frost kills the vine, but the plant will redirect energy to mature the other fruits.

Acorn Winter Squash fruits

Winter squash are infected with the same pests and diseases as pumpkins. Check out the pumpkin section for details on these problems.

Harvest

Let winter squash mature in the garden until they develop the mature skin color for that variety. The skin should be so thick that it feels hard when you press your thumbnail into it. Cut fruits so a 2-inch long stem remains. Harvest before a killing frost to protect the fruits from rotting in storage. The cold will weaken the skin. Wipe the skins clean with a 10% chlorox solution to kill disease spores, cure in a warm 80F room for 2 weeks, and then store for up 3 to 4 months in a 50F dark airy location.

Additional Information

‘Waltham Butternut’ has a moist, sweet orange flesh. ‘Table Queen’ acorn has a sweet, nutty flesh flesh. My favorite kaboucha or buttercup squash variety is ‘Sunshine Hybrid’ with its bright orange skin and dry, sweet flesh. It’s great for baking or making pies. Spaghetti’ squash is unique because the moist, yellow flesh is stringy when cooked, and makes a fun pasta substitute.

While most varieties of winter squash can vine for 10 to 20 feet, ‘Cornell Bush Delicata’ produces 2 pound, sweet yellow fleshed fruits on a zucchini-sized plant.

Excepted from the Northeast Vegetable and Fruit Gardening book.

Growing Vines

Learn about a wide variety of annual and perennial vines to grow including mandevilla, passion flower, trumpet vine, honeysuckle and morning glory. Includes varieties, how to grow, prune and fertilize the vines and fall and winter care.