There's a winter squash for everyone and every garden, from huge plots to tiny backyard spaces. If you're looking to add tasty produce by the pound (or many pounds) from your garden, winter squashes are the ticket.

Although we call them winter squash, they're grown in the heat of summer. The name "winter squash" comes from the season in which we typically eat them, as they store well, and some actually develop a better flavor after a month or two of storage.

While we normally plant winter squash in early summer, it's not too late for many gardeners in the US. With first frost dates extending into October and November in many regions, planting winter squash in the summer can be a space-effective way to utilize beds that were recently full of potatoes, garlic, onions, or spring crops and get some high-quality squash to store away for delicious recipes on cold winter nights!

Choosing a variety of winter squash

I must confess, I'm a bit of a winter squash fanatic, and if I had space, I'd grow them all. However, when choosing varieties, it's important to consider four main factors: plant size and form, days to maturity, disease resistance, and fruit (squash) size. Of course, taste always matters, and if you already have a favorite, that's the one to prioritize.

Winter squash plants come in semi-bush and vining forms, and some can sprawl over a lot of real estate just like pumpkins. Semi-bush varieties have a more compact habit, although they are still relatively large plants. Vining varieties need a bit of tending and like to spread out, harvesting sunlight with huge leaves and sending vines everywhere. It’s possible to train the vines to grow where you want them, but be aware that these plants can become large and are difficult to manage in small spaces.

Like many other crops, winter squashes can be early or later maturing. The days to maturity listed on the package refer to the period from when the seeds were planted until, theoretically, the first harvest. Some varieties, such as early butternut hybrids, can be ready in as little as 80 days, while others, like Blue Hubbard, require over 100 days. If you're a short-season gardener or getting your plants in late, choose the quicker varieties.

For many gardeners, powdery mildew is a nuisance, and it loves the big green leaves of squash and pumpkins. However, it can be quite a problem, and choosing varieties that are resistant to powdery mildew can help. 

Lastly, a note about size. I once grew a thirty-pound Hubbard squash. It was gloriously pale blue, knobby, and beautiful–but what do you do with a thirty-pound squash? A bit big for the oven. Fortunately, many of the older varieties, which produced squash only one size — large — have been bred to produce smaller fruits, including single-serving-sized squash. Check the size of the fruit, especially if you don't wish to use an axe in the kitchen to break down a giant one. Squash sized to provide one meal for your household are much easier to prepare and cook. Unless you like big squash, and you cannot lie.

How and When to Plant Winter Squash

Winter squashes like to be planted directly in the ground. The traditional way is to make a small mound of soil, plant 4-5 seeds about an inch deep, and once they germinate, thin the plants, leaving the two strongest. However, they can also be started indoors if you have problems with birds and rodents stealing your seeds or a short growing season necessitates a head start. If starting them indoors, plant them in individual containers (three-inch pots work well). They'll need artificial light to avoid getting spindly.

Whether transplanting started squash or direct seeding, wait until all danger of frost has passed and the soil has warmed. They won't germinate well in cold conditions, and the seeds may just sit there and rot in cold, damp soil. About two weeks after your last frost is normally a good time. 

If starting squash indoors, be mindful that they germinate and grow quickly and can become too large in a hurry. Ideally, they'll just be putting out a true leaf when transplanted, so start them no sooner than about a week or two before your last frost.

Soil, Sun, and Water Needs

Winter squash, like pumpkins, as well as summer squash and cucumbers, prefer full sunshine. Six or more hours per day is ideal, although you may still get a few squash with less. They love good sandy loam soil, but the most important factor is that it drains well. Consistently damp, heavy soil can lead to root and crown rots. 

During the heat of summer, you may notice that squash leaves droop slightly, then perk up after the sun goes down and appear fine again by morning. If you're having a record heat wave, that's normal. Otherwise, it indicates it's time to water. 

Squash typically does well with the general veggie garden recommendation of one inch of water per week, but this will vary depending on your soil type and weather conditions. Water squash when the soil begins to feel dry to your finger. Watering deeply once or twice a week is more effective than daily shallow watering. While avoiding overhead watering is best for controlling powdery mildew, if you water from above, do so in the morning so the leaves are dry going into the cooler temps of evening.  

Growing Tips for Winter Squash

Winter squash, once established, will grow and vine and fruit, usually without help from us. They'll seem to be growing slowly and then take off overnight. 

• Mulch under and around the vines will help to keep weeds under control. They have shallow roots, so be careful hoeing or cultivating near the plants.

• Rearrange wayward vines when they’re young. They become harder to move when they’re older. 

• Larger squash varieties will benefit from having the fruit held off the soil by a scrap of board or brick.

• In fertile, loamy soil, they won't need any additional fertilizer. For more nutrient-poor sites, apply a balanced NPK ratio fertilizer, such as 10-10-10, once a few true leaves have appeared and again a month later. Avoid heavy nitrogen fertilizers as they will encourage prodigious vine growth but at the expense of a later fruit set.

Common Pest Issues

• Powdery Mildew: This fungal pathogen rarely kills squash but can stunt them if the fungus, which appears as white dust, becomes thick enough to inhibit photosynthesis by blocking sunlight from reaching the leaves. Water in the morning, water at the soil level if possible, and choose resistant varieties. 

• Squash vine borer: This insect pest is a real problem in some areas. The vines appear healthy but then suddenly begin to wilt and die within a few days. Northern gardeners have one generation of larvae to deal with, while those in the South may have two. Check out this pub from the University of Wisconsin Extension for methods to battle this pest.

When to Harvest Winter Squash

Like pumpkins, winter squash will turn to their mature color as they near being ready to harvest. Changing color is the first sign your squash are nearing maturity. Here are a few more signs your squash is ready for the kitchen or storage.

• The rind should be hard enough that your fingernail doesn't easily make a mark. If you can sink a fingernail into the skin of the squash with normal effort, it isn't ready yet.

• Unripe squash is sometimes shiny, but ripe squash is less so. Wait for the skin to become matte, not glossy. 

• Look at the stem; it should begin to harden, start to dry, and become a bit woody. The fingernail test works well here too.

When harvesting winter squash, use pruning shears to snip the squash off, leaving about an inch of stem intact. If you accidentally broke the stem off, use those squash first, as they likely won't store as well. 

For squash which you'll eat or process in a few weeks no curing is necessary. But, for longer storage, curing helps to harden the skin and improve the shelf life. After harvesting the squash, let it sit in the yard on a pallet or your picnic table for a few days. The curing process needs about a week of warm (room temperature) and dry weather. If needed, you can bring the squash into the garage or even the house. Space the squashes so air can flow between them while curing. 

Storing Winter Squash

Besides the fun of harvesting beautiful, colorful, heavy squash and the feeling of success and security a pile of squash brings, they are wonderful table fare. But, to properly appreciate them, you'll need to store them. 

Most winter squash will store for a month or longer without any special treatment, even when left on the counter. However, for long-term storage, you'll want to consider temperature and humidity. Most winter squash are easily stored for up to two months, and some varieties can last six months or longer.

Winter squash stores best at temperatures between 50 and 55°F. But while that exact range is ideal, what you really need is a cool, dry location. A corner of an unheated basement often works well. Store squash (and any produce) up off the ground, not directly on the cement floor. An old wood pallet or a shelf works well. Keep them away from apples and other fruits, which emit ethylene gas and shorten the lifespan of other produce, such as squash and pumpkins.