Growing Butternut Squash For Fall Flavor - Epic Gardening

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Nothing quite signals the arrival of autumn like a steaming bowl of butternut squash soup. A type of winter squash, it grows through spring and summer but stores well into winter on a pantry shelf. Butternut squash can be used in countless dishes, from roasting and adding to tacos to pureeing for soups and pies. For gardeners and home cooks growing butternut squash, patience is key.

Like all squashes, butternuts are native to the Americas and have a long history of cultivation there. Butternut squash is considered a modern variety of winter squash, as squashes have been cross-pollinating and producing new forms for thousands of years.

The butternut squash we know today was developed by Charles Leggett of Stow, Massachusetts, in 1944. Since then, additional variations have been bred from this original type, including smaller cultivars such as honeynut squash and butterbaby.

Squash plants produce highly nutritious fruits, and butternut squash is rich in vitamins A, B6, C, and E while remaining relatively low in calories. The seeds are also edible and are traditionally thought to help calm the nerves. With its versatility in the kitchen and long storage life, it is easy to see why many gardeners and homesteaders consider butternut squash a pantry staple.

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Waltham Butternut Winter Squash

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Quick Care Guide

Scientific Name Cucurbita moschata Days to Harvest 110-120 days plus curing time Light Full sun  Water 1 inch of water per week

Soil Rich, well-draining, with pH of 5.5-7.0 Fertilizer A balanced fertilizer (10-10-10) at planting, flowering, and setting Pests Vine borers, squash bugs, cucumber beetles Diseases Powdery mildew, downy mildew, anthracnose

All About Butternut Squash

Butternut squash plants, or Cucurbita moschata, are one of the most popular and recognizable winter squashes. Known in Australia as the butternut pumpkin, this vegetable originates from the Americas and has since been introduced worldwide, with each culture putting its own spin on how it is prepared and enjoyed.

Butternuts are a type of winter squash, along with acorn, kabocha, and spaghetti squash. They are close relatives of summer squash, such as zucchini and patty pan squash. While both are grown during the same growing season, the key difference lies in their skins.

Summer squash has thin skin and a short shelf life, while the thicker skin of winter squash allows it to be grown in summer, harvested in fall, and stored for winter use. Depending on the variety, winter squash can keep on a kitchen counter or cellar shelf for between two and six months.

Even within the butternut group, there is a wide range of varieties to choose from. The classic ‘Waltham’ butternut is likely the one most people picture when they think of butternut squash, but many subtypes exist. For smaller households, honeynut and butterbaby are compact, single-serving options. For those cooking for a crowd, the ‘Tahitian Melon’ squash can grow exceptionally large, sometimes weighing as much as a small child.

Characteristics

A garden full of butternut squash plants can look delightfully wild. The long vines weave their way through garden beds, over fences, and occasionally into small trees. Large, spade-shaped leaves shade the developing fruit and help keep the soil moist.

Bright yellow flowers appear along the vines to enable pollination. Baby butternuts with a flower attached are female, while flowers on long stems are male. Depending on the variety, you can expect between three and 15 squash per plant.

You do not need to be an expert gardener to grow squash. Squash seeds germinate easily when conditions are right. They are often grown as part of the traditional Native American planting method known as the Three Sisters, where squash, beans, and corn are sown together in mounds during spring. The raised soil warms more quickly, helping seeds germinate faster while the sprawling squash vines suppress weeds and conserve moisture.

Planting

Butternut squash plants are annuals grown through spring and summer. While they can take around 110 days to mature, they also need about two weeks of curing in the sun if you plan to store them. Count backward from your first frost date to be sure you allow enough time for both growth and curing.

When starting squash from seed, begin indoors in cooler climates and transplant outdoors once all danger of frost has passed. In warmer climates, you can direct sow seeds in an area of the garden where the soil has warmed to at least 70°F (21°C) for proper germination. Ideally, sow seeds in mounds spaced several feet apart, placing four to five seeds in each mound. Be sure the area is well mulched, preferably with well-rotted compost, as these plants are heavy feeders.

Squash are vigorous growers and can quickly take over large areas of the garden. Because of this, they require full sun and well-draining soil. When grown in containers, choose a pot that is large enough, at least 18 inches wide and 18 inches tall, to accommodate their sprawling habit.

Once the seeds sprout, thin seedlings to two to three plants per mound. Water at the base of the vines about once a week, taking care to keep the leaves dry to reduce pest and disease issues.

After a few weeks, small butternuts will form where the flowers once were and will grow rapidly. Place a barrier between the developing squash and the soil to prevent pests like pill bugs from feeding on the underside. Cardboard works well for this. Allow the squash to mature fully, turning tan in color, and wait until the stem has completely dried before harvesting.

How to Grow

Butternut squash plants will almost grow themselves under the right conditions. All the home gardener needs to do is find the right spot in their garden and watch these vines take off!

Light

When you set out to grow butternut squash, find the portion of your garden with the most sun and warmth. Butternuts require full sun, not just where the seeds are sown, but throughout the large area they will take up.

Water

Water butternut squash once a week throughout the growing season at the base of the vine, ideally using a drip line or soaker system. Each plant needs at least one inch of water per week during early growth, increasing to one to two inches once large fruit has set.

Avoid watering too frequently, as excess moisture can cause the squash to crack when the plant absorbs water faster than it can form new skin. Once the squash has fully tanned and the stems begin to dry, stop watering to further reduce the risk of cracking.

Soil

Squash needs well-draining, loamy soil, as it is a shallow-rooted plant. Keep the soil moist but not wet, especially while the plants are still young. Squash can survive in poor-quality soil, but this often results in fewer fruits. They are not especially picky about soil pH, tolerating a range of 5.5 to 7.0. Mulch generously to add nutrients and help retain soil moisture.

Temperature

These plants will only survive once the danger of frost has passed and daytime temperatures consistently reach 70°F (21°C).

A single frost can kill even a well-established plant. During peak summer heat, leaves may wilt during the day. Avoid overwatering, as plants usually perk up again in the evening. Butternut squash grows well in zones 3 through 10, with a longer growing season the farther south you garden.

Fertilizing

To grow butternut squash successfully, plan to fertilize three times during the growing season. These plants are heavy feeders and benefit from a balanced 10-10-10 fertilizer while they are young. Once fruiting begins, switch to a fertilizer that is lower in nitrogen.

Nitrogen promotes leafy growth, but too much can come at the expense of fruit production. Be careful not to overapply nitrogen, as this can result in vigorous vines with fewer squash.

Pruning & Training

If you plan on letting your squash roam freely in the garden, you likely will not need to train it much. Once a vine has three to four fruits, clip off the end of the vine to stop further production. The quality of butternut squash can decrease if too many fruits are allowed to develop on a single plant.

One way to save space in the garden is to train squash vines up a trellis or arch. This also helps keep vines off the ground, where they are more likely to encounter diseases and pests. While the plants are still young, gently train the vines onto the trellis, securing them with string or wire.

Be sure to do this early, as moving larger vines can cause breakage and stunt growth. Once the butternuts form and begin to hang, provide extra support so they do not snap off. You can do this by cradling the fruit with pantyhose, old t-shirts, or kitchen towels tied to the trellis.

Propagation

Most butternut squash plants are grown from seed. Unless you live in a warm climate or have access to a large greenhouse, starting from seed is the only practical way to grow butternut squash.

Rooting cuttings is rarely attempted and is usually done only to preserve an heirloom variety or rescue a damaged vine. To do this, use a rooting hormone and place the cut end of the vine into soil mixed with vermiculite, keeping it lightly moist until roots form.

Harvesting

Butternuts are prized in the garden in part because they store well over winter. They make it possible to enjoy a taste of summer even when there is snow on the ground outside.

Butternuts are ready to harvest when the stem attaching the fruit to the vine is completely dried out and the skin cannot be pierced with a fingernail. There are a few additional signs you can use to judge readiness, which are covered in more detail in our separate article on when to harvest winter squash.

Cut the stem about one inch away from the fruit and allow the squash to dry in the sun for about two weeks. This process is known as curing. If you plan on long-term storage, wipe down the cured squash with a mild bleach and water solution to kill mold spores and insect eggs that could damage the squash during storage.

Storing

Once butternut squash has been properly cured and cleaned, it can last two to five months when stored at 50 to 60°F (10 to 16°C) in a well-ventilated cellar or pantry. Do not stack squash on top of one another, as good air circulation is essential. Check stored squash regularly for signs of rot, since one spoiled squash can quickly affect the others.

Butternut squash can also be cubed and pressure canned using a tested, safe recipe. Freezing is another excellent option. Dice the squash and spread it out on a parchment-lined baking sheet until frozen, then transfer it to a freezer bag. Cooked squash can also be dehydrated, although the texture may change once rehydrated.

Troubleshooting

From fruit not setting to wilted leaves and a white substance covering the butternut’s leaves, several problems can plague these crops during the growing season. 

Growing Problems

One of the most common growing problems is the failure of female flowers to set fruit. Small butternuts may appear, then turn yellowish brown and fall off, which can be disappointing for gardeners.

This usually happens when pollen from the male flowers does not reach the female flowers in time. Pollinating insects normally handle this task, but when they are scarce, hand pollination may be needed to ensure your squash develops properly.

Splitting occurs when the plant receives too much water over a short period. The flesh inside the squash expands faster than the skin can keep up, causing cracks. If the squash is fairly mature, it can still be eaten within 48 hours.

Pests

One of the most annoying parts of growing vegetables is dealing with the pests that want to eat them, too. There are a few main insect predators to watch out for when growing butternut squash.

Squash vine borers attack squash plants by boring into the main stem, where they feed on plant juices and internal tissue. This causes small holes in the vines and leaves behind frass, a sawdust-like material around the entry point. You can discourage vine borers by spraying neem oil to kill their eggs. Wrapping the base of young vines in aluminum foil also prevents adults from accessing the stems, protecting seedlings from serious damage.

Squash bugs are small gray or brown insects that often appear in groups. They lay their eggs on the undersides of leaves, and once hatched, the nymphs suck sap from the plant. Insecticidal soap or neem oil can be used to smother eggs, while pyrethrin is effective at controlling adult bugs.

Cucumber beetles are small insects with yellow and black markings on their backs. They target young seedlings in particular and can transmit wilt diseases. Both pyrethrin and spinosad are effective treatments for managing cucumber beetle populations.

Diseases

Most butternut squash diseases can be avoided by choosing varieties with proven disease resistance. Keeping the garden well-weeded and encouraging good air circulation also goes a long way toward reducing disease pressure.

Anthracnose first appears on butternut squash leaves as small circular spots or shallow indents, but it can quickly spread to cover the entire plant. Treat early with a copper fungicide, as this disease can kill a plant rapidly. Be sure that infected plants are never added to a compost pile or worm bin.

Downy mildew, like most fungal diseases, thrives in moist conditions and can be fatal if left unchecked. It appears as pale gray or yellow spotting on the leaves. Prevention is key, and copper-based fungicides work well. Neem oil can also be used as a preventative measure.

Powdery mildew is easy to identify by the white, powdery coating that forms on the tops of leaves and stems. If not controlled, it can spread across the entire plant and significantly stunt growth. Remove affected leaves and treat with neem oil to keep the disease in check.

Frequently Asked Questions

How long does it take to grow butternut squash?

It takes between 100-120 days to grow but another 2 weeks to cure it if you intend to keep it in long-term storage.

How many squash do you get from one plant?

Depending on the variety and growing conditions, you can expect between 5 and 20 butternut squash per plant.

Do I need to dry butternut squash seeds before planting?

Yes. Butternut squash seeds need to be fully mature before they’re planted.

Can I plant seeds from store-bought squash?

You can. However, you may find that the seeds cross-pollinated while growing and will grow to create a different type of squash.