Growing Winter Squash

All winter squash varieties are easy to grow, and butternuts, buttercups and other types with dense flesh can stand in for carrots, pumpkins and sweet potatoes in any recipe.

Butternut squash combine rich flavor and smooth texture with natural resistance to squash vine borers. These bottle-shaped fruits have buff-brown rinds and will store for six months or longer.

In spring, sow seeds in prepared beds or hills after your last frost has passed, or sow them indoors under bright fluorescent lights. Set out seedlings when they are about three weeks old. In Zone 6 and warmer, you can plant more winter squash in early summer, using space vacated by fall-planted garlic or early spring lettuce. Stop planting winter squash 14 weeks before your expected first fall frost.

How to Plant Winter Squash

Winter squash grows best in warm conditions, in fertile, well-drained soil with a pH between 6.0 and 6.5. Choose a sunny site and prepare 3-foot-wide planting hills within wide rows, or position them along your garden’s edge. Leave 5 to 6 feet between hills. Loosen the soil in the planting sites to at least 12 inches deep. Thoroughly mix in a 2-inch layer of mature compost and a light application of balanced, organic fertilizer. Water well. Plant six seeds per hill, poking them into the soil 1 inch deep. After seeds germinate (about 10 days after sowing), thin seedlings to three per hill. Set up protective row covers as soon as you’re done planting.

Harvesting and Storage

Fruits are ripe if you cannot easily pierce the rind with your fingernail. Never rush to harvest winter squash, though, because immature fruits won’t store well. Unless pests or freezing weather threaten them, allow fruits to ripen until the vines begin to die back. Expect to harvest three to five squash per plant. Use pruning shears to cut fruits from the vine, leaving 1 inch of stem attached. Clean away dirt with a soft, damp cloth, and allow fruits to cure for two weeks in a spot that’s 70 to 80 degrees Fahrenheit. Store cured squash in a cool, dry place, such as your basement, a cool closet or even under your bed. Check every two weeks for signs of spoilage.

Winter squash face challenges from squash bugs, squash vine borers and cucumber beetles. To defend your plants from all three insects, shield them with row covers held aloft with stakes or hoops until the plants begin to bloom. Big, healthy plants will produce well despite pest pressure. Among diseases, powdery mildew is a common problem best prevented by growing resistant varieties, which often have “PMR” (for “powdery mildew resistance”) after their variety names. In addition, a spray made of 1 part milk and 6 parts water can suppress powdery mildew if applied every two weeks during the second half of summer.

Winter Squash Growing Tips and Ideas

Grow open-pollinated varieties so you can save your own seeds for eating and replanting. Only choose hybrids if you need a space-saving bush habit or a special form of disease resistance.

Try growing winter squash in an old compost pile located along the edge of your garden. Small-fruited varieties do well if allowed to scramble up a fence.