How to Plant, Grow, and Care for Acorn Squash

Growing acorn squash is low maintenance and rewarding! Because of their large seed size, sowing acorn squash seeds is a great task for young children to get them involved in the garden. If you’d rather begin with pre-started seedlings, then fear not! Squash seedlings are likely available at your local garden center. The growing process is long, but you’ll enjoy watching the acorn squash grow throughout the summer and into the fall. 

This species originated in Central and North America and was introduced to early European settlers by Native Americans. It was a staple crop and often part of a three-sisters garden, which includes corn, pole beans, and squash, all of which are interplanted for their mutual benefits. 

Acorn squash is very easy to prepare and cook which makes it a great addition to every edible vegetable garden. The flavor has been described as mild and slightly nutty. It requires no peeling, just slice in half and roast cut side down in the oven until tender. Top it with some butter, and a sprinkle of salt, and eat the flesh right out of the rind. Acorn squash is also an excellent stuffable squash since they have a shape that is nearly perfect for stuffing. Half a squash makes for a perfect serving size. (Also, they taste incredible when stuffed with mushrooms and wild rice!)

What is Acorn Squash?

Cucurbita pepo var. turbinata is also known as Des Moines squash and pepper squash. They are a type of winter squash, but are more perishable and have a shorted shelf life than others of their kind. They can also be eaten somewhat immature, whereas other winter squash should fully mature before being harvested. C. pepo includes vegetables such as butternut, spaghetti squash, and pumpkins. Summer squash such as zucchini is a subspecies of Cucurbita pepo. It is said that the name Des Moines squash comes from a popular variety, ‘Table Queen’, that was first sold by an Iowa seed company and gained popularity in the 1800s. 

Native Area

There is some mystery around the Des Moines cultivars and there are claims of it being cultivated in Denmark, however, these claims have been unsubstantiated and it’s more likely that it was cultivated alongside other squashes in North America. The original Cucurbita pepo is native to Mexico.

Characteristics

These vegetables have large fan-like leaves and thin stems that will either lead to a central growing point (for bush types) or to a vine (for vine types). The flowers are large and yellow and resemble zucchini blossoms. They are also edible and taste amazing when battered and deep-fried. The shape of the squash resembles an acorn with ribs and a dark green rind sometimes with a tinge of orange. 

People grow acorn squash because they’re high in Vitamin C. 

Planting

The best time of year to sow acorn squash seeds is after all danger of frost for the season has passed. Pick a spot in your garden that gets plenty of sunlight and has plenty of space for the plants to bush out, sprawl, or grow up a raised bed trellis depending on the variety that you choose. Keep in mind that the decision to sow directly from seed or transplant out seedlings will depend on the length of your growing season.

If sowing acorn squash seeds directly, start planting after the soil temperature is consistently at least 60°F. When transplanting seedlings, wait until one to two weeks after the average last frost date when nighttime temperatures are in the 50s. Make sure to space accordingly. Place one transplant per two square feet. Thin direct-sown squash in the seedling stage to this same spacing.

How to Grow

Now we’ll discuss the care of the beloved winter squash. Hopefully, this encourages you to add it to your vegetable garden as soon as possible! Following these gardening tips will ensure a bountiful harvest. 

Light

Acorn squash love full sun! They will require at least six to eight hours of direct sunlight per day. They can tolerate partial shade when grown in a three-sisters situation, but it’s best to grow them around the perimeter so that they are still getting adequate sunlight. Although they love sunlight, they don’t do well in excessive heat. In extreme heat (temperatures above 90°F) when the sun is beating down on them with scorching intensity, the flowers may drop and fruit may fail to form.

Water

Since acorn squashes are particularly susceptible to powdery mildew and downy mildew, it is a best practice to water them early in the day and water at the base to prevent wetting the foliage. As a general rule squashes require moist, well-draining soil.

Water deeply once per week. It is easiest to place young seedlings along drip irrigation lines to ensure that they receive this deep watering without wetting their leaves. Acorn squash leaves may wilt slightly in the heat of the day, but fear not, this is not a sign of underwatering. They will perk back up once the sun begins to set and the heat of the day has passed.

If you witness wilted leaves early in the morning, before it is hot outside, you may consider increased watering. The general guidance when growing acorn squash is to keep the soil moist but not soggy. 

Soil

Acorn squash prefers well-drained soil that is rich in organic matter. A layer of compost at the beginning of the growing season will help accomplish this. They can create a complex root system that can inhabit the top eight to twelve inches of soil. Working compost into this top layer of soil will get them off to a great start.

You can grow acorn squash in a five-gallon bucket as long as the same soil requirements are met. However, their root systems generally spread wider rather than deep, so container growing is not the best option. Give squash about two square feet between it and other vegetables.

Temperature

Acorn squash can be grown in zones 3-10, but prefer warmer climates and do best in hardiness zones 5-9 where it isn’t too cold and also isn’t too hot. 

Like most in the Cucurbita family, they cannot handle even a light frost (which occurs at 32°F). Acorn squash seedlings will need to be transplanted out one to two weeks after the last frost when soil temperatures are consistently at least 60°F.

It’s very difficult to protect even with row covers during cold periods so your best bet is to wait until the last spring frost has passed. If you live in an area with a long enough growing season, sow your seeds directly. In areas with short growing seasons, start plants indoors to give them a head start and then transplant them out. To calculate the length of your growing season, determine the number of days between your last frost in spring and your first fall frost date. 

Fertilizing

When you grow acorn squash, its complex root system and large size make them natural heavy feeders. For this reason, they can benefit greatly from a good all-purpose fertilizer. Fertilize every three weeks during the growing season. Once it begins to set fruit, switch to a fertilizer low in nitrogen and high in potassium and phosphorus for good fruit development. Use a liquid fertilizer watered around the drip line. 

Maintenance

Pruning for acorn squash is unnecessary other than removing dead or yellowing leaves. Cut them back at the base of the stem. When pruning away damaged or diseased leaves, be mindful not to cut through the main stem. Otherwise, they can take pruning at many locations without inhibiting its growth. 

There are two main acorn squash varieties: bush and vining. The bush variety will remain stout and, well, bushy. The vining varieties resemble butternut and can be trained to climb a trellis. This may be useful if you’re limited on garden space. This will allow you to grow acorn squash vertically and make the most of all the square footage available in your vegetable garden. 

I’ve had the most success growing winter squash on a cattle panel trellis. Set your acorn squash seeds or starts at the base of the trellis and once it is tall enough to do so, weave it through the first few spaces on the cattle panel. Squash will take it from there.

If you’re growing vertically, support the weight of the fruit once it begins to mature to prevent it from bringing down the entire vine. Create a cradle out of old pantyhose or an old t-shirt. Although they can generally withstand the weight of the fruit without much support, it is better to be safe.

With the bush variety, you may consider adding a barrier between the squash and the soil as it matures. Without a barrier, like a piece of slate, the squash may rot on the side that rests on the ground. This is an issue in areas that are especially moist and wet while the fruit is maturing; otherwise, it shouldn’t be an issue. Follow these growing tips, and you’re sure to have a successful squash season.

Propagation

Acorn squash can only be grown from seeds and cannot be propagated from cuttings or other methods. To give your acorn squash seeds the best start, sow five or six seeds in a mound about an inch deep and loosely cover with soil. Once they emerge, thin weaker seedlings when they’re about three to four inches tall and have their first true leaves. You can save seeds from season to season, however, members of the Cucurbita family very easily cross-pollinate, so if you’ve planted other members of this family nearby, then any seeds that you save may turn out to be a franken-squash rather than true to type. 

Harvesting

As mentioned above, the blossoms can also be harvested and eaten. If you choose to do this, make sure to harvest only the male blossoms as you’ll want to leave as many female blossoms as possible to turn them into mature fruit. 

It’s important to harvest acorn squash before the first hard frost. Although they are referred to as winter squash, they do not do well in cold temperatures. They are called so because, unlike summer squash, they will form a thick skin that allows them to more easily be stored over winter rather than eaten fresh in the summer. Other squashes like this include spaghetti, butternut squash, and pumpkins. 

You’ll know that they’re ready to harvest when the ribs are dark green, the skin is firm to the touch and the stem begins to turn brown. They continue to ripen slightly after they are harvested and there is no danger in eating an immature fruit. The deep green color of the skin, the browning on the stem, and the dying back of the vine/bush are all great indicators. 

Once you’re ready to harvest, grab a pair of sturdy pruners. It is not recommended to try and pull this fruit from the vine with your hands as you may damage the vine and jeopardize the remaining fruits. Cut the stem about two to three inches above the fruit. Leaving some of the stem intact will help lengthen the time that you’re about to store it long term. After harvesting, if there is no acorn squash further down the vine, then you will be able to prune back this section so that it can focus on ripening any remaining fruit.  

Storage

To store acorn squash for the long term first you’ll need to sort through them. Any squash without their stem, with any soft spots or any type of damage to the outer rind, should be eaten immediately as they will not store well. Leaving the stem attached is an important step as the lack of an intact stem will allow moisture to get inside and rot your acorn squash. They can go through a process of curing outside, in a cool dry place, around 55°F such as a root cellar, garage, or basement. Leave them for a few days until the stem has hardened completely. 

Acorn squash is one of the most perishable winter squashes. To ensure a longer shelf life, wipe them down with a solution of one part household bleach to ten parts water, which will discourage rot and mold growth. Generally, they can keep for three to four weeks but can last longer in ideal conditions. 

Common Problems

Although this is a relatively low-maintenance and straightforward to grow, there are a few pest issues to address. Read on to find out how to stay ahead of them! 

Growing Problems

As mentioned above, acorn squash plants do not appreciate extreme heat. Prolonged temperatures above 90°can cause the flower to drop, and then the fruit fails to form. In times of intense heat, provide them with shade cloth to help ease the stress. Watering in the morning will also help keep them cool throughout the day.

Like most members of the squash family, acorn squash have both male and female flowers. The male flower has a long thin stem and the female flower has a tiny acorn squash shape at the bottom that will turn into a viable acorn squash once it is successfully pollinated. If you notice that the tiny acorn squash is shriveling up then you likely have a pollination issue. If the female flowers fail to get pollinated, then they will shrivel up and die rather than producing fruit.

Attracting pollinators to your garden with companion plants such as dill, chamomile, nasturtium, and other flowering herbs is beneficial. When all else fails you can easily hand pollinate to ensure fruit production by taking a Q-tip and brushing it on the inside of a male flower, and then moving it to the inside of a female. 

Pests

Unfortunately, like many members of the Cucurbita family, acorn squash also has many common pests that are specialized in destroying this vegetable. Among these insect pests, cucumber beetles, squash vine borers (SVB), and squash bugs are the most common. SVB, as their name suggests, bore into the vines where they lay their larvae. This prevents it from taking up water and it will eventually wilt and die.

These pests are found in the eastern United States. Once they have bored into the vine it’s possible to bury another section of the vine in the dirt to get it to root, but this has varying degrees of success depending on the damage that has already been done. Bt spray can be used to destroy vine borers and can even be injected into the stem to kill their larvae. 

Crop rotation can be a good preventative measure because it prevents overwintering pests from emerging alongside your newly planted seedlings. Clearing away vines at the end of the season. Cut at the base as close to the soil level as possible. The roots can be left in place to add organic matter to your soil while the rest should be discarded. It is not recommended to compost if you suspect a potential pest issue. 

With most of these pests, the best defense is a good offense. Be vigilant and inspect your often. Squash beetle eggs are particularly easy to spot. They lay their eggs on the undersides of the leaves, and they appear small, oblong, and bronze. It’s easy enough to squish them between your fingers. Adult bugs can be picked and dropped into a bucket of soapy water to kill them. They also make an excellent snack for your chickens. 

Diseases

Overwatering can cause the perfect conditions for fungus to take hold, especially in hot and humid climates. If too much moisture splashes onto the foliage during watering then this can contribute to issues with downy mildew. 

Downy mildew is often mistaken for powdery mildew but it appears as yellow leaf spots on the tops of the leaves with black spore masses on the underside of the leaves. In contrast, powdery mildew appears as more of a white flour-like powder on the leaves. 

To prevent these issues, always bottom water your plants, neem oil may also be sprayed as a preventative measure to reduce the colonization of spores on foliage. In advanced cases of this mildew, it may be best to remove and destroy infected plant material to prevent it from spreading to nearby healthy vegetables.

Frequently Asked Questions