Winter Squash

Winter squash isn’t something you grow in winter.

Instead, the terms winter squash and summer squash refer to when these crops are eaten, not when they are grown. Thin-skinned summer squashes, such as zucchini and yellow crookneck, are best eaten fresh, while immature. Sturdy, thick-skinned winter squashes can be stored for several months. Their hard, protective rinds are generally removed before eating and their seeds are delicious when roasted with a little oil and salt. Acorn, butternut, Hubbard, and turban squashes are all winter varieties. So are pumpkins.

Winter squash (Rudi Riet) CC BY-SA 2.0

Did you know that most canned pumpkin puree is actually squash? Pumpkins and other winter squash share enough characteristics as to be indistinguishable according to the FDA. Huh. How about that? No matter. Growing pumpkins and other winter squash can be very rewarding and easier than you may think.

How to grow winter squash

Winter squash grows best in full sun, but it seems to perform just as well in partial shade in areas with especially hot summers. (I have successfully grown butternuts under a nectarine tree and they both seemed happy about it.)

After temperatures have reached a steady 70°F, winter squash seeds are planted in hills. Each hill gets 4-5 seeds. If you have room for multiple hills, they should be spaced 4'-8' apart, depending on the type of squash being grown. After your seedlings are 2"-3" tall, select the best two or three for each hill and snip the rejects off at soil level. If you are growing winter squash in rows, seeds should be planted 6"-12" apart in rows that are 6'-10' apart, thinning seedlings to one plant every 18"-36". These plants can take up a lot of space, given the opportunity. You can also redirect them along walkways, lawns, or fences. Depending on the size of the fruit, you may need to provide hammocks as support.

Butternut squash trained up a trellis (Kate Russell)

It takes a lot of water to make a winter squash. During fruit set, each plant should receive approximately 1" of water per week. (One inch of water is equal to 0.623 gallons per square foot.) Since most winter squashes are shallow-rooted, it is not a good idea to disturb the soil. Butternut squashes are something of an exception, with deeper root systems that help them through scorching summers and drought. Keep your squash watered and mulched and you are sure to get an abundant crop.

Winter squash problems

Winter squashes are members of the melon family. Also known as cucurbits, all members of the melon family are susceptible to several diseases and disorders:

• angular leafspot
• bacterial leaf blotch
• bacterial wilt
• belly rot
• charcoal rot
• cucumber mosaic
• cucumber vein yellowing
• cucurbit aphid-borne yellows
• cucurbit yellow stunting disorder
• curly top

• Fusarium crown and root rot
• mosaic virus
• Phytophthora root and crown rot
• root rot
• powdery mildew
• potyviruses
• squash mosaic
• sudden wilt
• white mold
• zucchini yellow mosaic​

Many of these problems can be prevented by avoiding overhead watering and managing disease-carrying aphids.

Powdery mildew on butternut squash leaves (Kate Russell)

​Along with aphids, the following pests may appear in your winter squash patch:

• cucumber beetles ​
  
• darkling beetles
• dried fruit beetles
• false chinch bugs
• leaf-footed bugs
• melonworm moths
• mites
• pickleworms

• redhumped caterpillars
• seedcorn maggots
• squash bugs
• squash ladybugs
• squash vine borers
• stink bugs
• whiteflies
• wireworms

​Winter squash plants need to be watered regularly to prevent blossom end rot, bitter fruit, and blossom drop.

If all that weren’t enough, molybdenum deficiencies can cause a condition known as yellows. Yellows eliminates squash fruit set and generally kills the plant. Sporadic watering and insufficient calcium can also cause blossom end rot. Soil tests from a reputable lab are the best way to learn what’s in your soil.

You might think, with all these threats to your winter squash crop, you might not get anything for all of your efforts. The truth is, winter squash plants are very productive, much like their summery cousin the zucchini plant. Despite all those potential problems, you will probably end up with plenty of winter squashes to share with friends and neighbors.

Fortuna white pumpkin plants (Kate Russell)

Butternut squash harvest from two plants (Kate Russell)

Harvesting winter squash

Winter squash are ready to harvest when the rind is firm and the stem is shriveled. You can leave them to cure on the vine or cut them off and store them in a cool, dry location with good airflow. Garages work nicely. After your winter squash has cured, it will remain edible for several months.

Dry winter squash lasts a long time.

Wet winter squash does not.