How to Grow Butternut Squash

For many gardeners, the end of the summer growing season is bittersweet. Even though warm-season crops like peppers, tomatoes, and zucchini are winding down for the year, it’s time to shine for winter squash. In this article, you’ll learn all about how to grow butternut squash, what its preferred growing conditions are, and how to harvest and store your crop of butternut squash at the end of the summer.

Growing butternut squash in your home veggie garden is as easy as it is rewarding. Squash plants have a rather long growing season, so it’s usually best to start seeds indoors in early spring or visit your local garden center to purchase nursery-grown seedlings after the last danger of frost has passed.

Butternut squash boasts a deliciously sweet, nutty flavor that many people enjoy in soups, roasted with sweet or savory spices, or incorporated in baked goods. Read on to discover the best tips and tricks for growing and harvesting the most delicious butternut squash you’ve ever tasted.

What to Know about Growing Butternut Squash

Butternut squash, or Cucurbita moschata by its botanical name, is a type of winter squash related to acorn squash and pumpkins. Other winter squash varieties include buttercup, delicata, Hubbard, kabocha, and spaghetti squash.

Butternut squash plants are warm-season annuals that grow well in most climates. Summer squash varieties like zucchini, crookneck, and yellow squash are harvested while still immature and have a soft rind. Winter squash remains on the vine until it reaches full maturity and has developed a tough rind.

Pollination is crucial for getting a good crop of butternut squash in the fall or when you grow spaghetti squash. Squash plants have separate male and female flowers.

The male flowers have a central stamen that produces pollen and female flowers have a pistil to receive the pollen and a small node at the base that eventually turns into fruit.

Consider companion planting with aromatic herbs and flowers to attract pollinators and other beneficial insects to your garden.

Depending on the variety, squash vines grow up to 10 or 15 feet long and may produce as many as 10 or 20 squashes per vine.

Some butternut squash varieties are bush-type plants that stay more compact, making them well-suited for smaller gardens and raised beds. Here are a few of the top butternut squash cultivars for home gardeners.

How to Grow Butternut Squash from Seed

Since most butternut squash varieties take three to four months to reach maturity, most growers plant seeds indoors in the late winter to early spring to get a head start on the growing season. When to best plant butternut squash inside is usually February or March. The same is true for when to plant pumpkin seeds.

It’s just as easy to grow pumpkins from seed, as well as other gourds and squashes.

Otherwise, when you plant spaghetti squash or butternut squash, purchase nursery-grown seedlings from your local garden center once the weather is warm enough for transplanting.

You might be wondering how to grow butternut squash from fresh seeds. If you’d like to collect seeds from squash purchased from the grocery store, it’s vital to select the healthiest squash possible. Make sure it’s organic and free from any deformities.

Scoop the seeds out of the center cavity, then place them in a colander. Rinse thoroughly, ensuring that they’re free from all of the fibrous matter. Spread them out on a dishcloth or paper towel to dry.

If you’re planting butternut squash seeds indoors, you’ll need a few supplies. If you don’t already have these items, they’re readily available online or at your local garden center.

Fill your seedling tray with a nutrient-rich potting soil blend designed for growing vegetables, and use peat pots or repurpose an old cardboard egg carton.

Sow the butternut squash seeds one inch deep, then lightly cover them with potting soil. Use a spray bottle to gently saturate the soil. Keep the soil moist while the seeds are germinating.

Germination typically takes seven to ten days. The optimal soil temperature for germinating butternut squash seeds is 70-95 degrees Fahrenheit.

Once your squash seedlings sprout, move them to a sunny windowsill that gets at least six hours of bright light each day. If you don’t have a south-facing window available, consider using a grow light to prevent your seedlings from becoming too long or “leggy.”

Transplanting Butternut Squash Outdoors

In most climates, the time for planting butternut squash seeds indoors is about six weeks before the standard last frost date for your area.

In warmer regions, it’s possible to sow butternut squash seeds directly in your garden beds anytime the soil is warmer than 60 degrees Fahrenheit.

Choose an area that gets full sun, meaning six or more hours of direct sunlight every day. Ensure that the plants get adequate airflow to prevent fungal diseases like leaf spot and powdery mildew.

Transplant indoor-grown squash seedlings after the last danger of frost passes. It’s helpful to apply a thick layer of dark-colored mulch, organic compost, or a sheet of black plastic to the planting area one week before transplanting your seedlings to warm the soil.

Give butternut squash plants plenty of room to spread out. Depending on which variety you’re growing, the vines sometimes reach up to 15 feet long.

Most gardeners opt for planting in hills or mounds of three squash plants to help provide better drainage away from the plant’s main stem and keep the soil warmer. Spacing between the hills should be about eight feet.

It’s also possible to train butternut squash vines to grow on a trellis. Varieties with smaller fruits don’t usually require additional support.

For larger cultivars, tie pieces of an old T-shirt or other flexible fabric to the trellis frame like a hammock to hold up the heavy fruits.

Best Soil for Growing Butternut Squash

Squash plants grow best in well-draining soil that’s rich in organic matter. Before planting, amend your soil with several inches of organic compost.

Other useful soil amendments include bone meal, used coffee grounds, composted manure, Epsom salts, and eggshells. The ideal soil pH for growing winter squash is neutral to slightly acidic, between 5.5-7.0.

Choosing the Right Fertilizer for Butternut Squash

In general, squash plants are heavy feeders and benefit from regular fertilizing throughout the growing season. Three predominant macronutrients are found in plant fertilizer: nitrogen (N), phosphorus (P), and potassium (K).

Nitrogen enhances green leaves, phosphorus promotes sturdy root systems, and potassium stimulates fruits and flowers.

When transplanting squash seedlings, add one tablespoon of organic, all-purpose fertilizer to the bottom of the hole. After that, apply a fertilizer that’s higher in phosphorus and potassium every three to four weeks according to the instructions listed on the product label.

If squash plants receive too much nitrogen, they experience an overgrowth of leaves followed by stunted fruit production.

How Long Do Butternut Squash Take to Grow?

Have you ever wondered, “How long do butternut squash take to grow?” The answer is, it depends on the variety, like when determining how long do pumpkins take to grow. Some kinds of butternut squash, like Burpee’s Butterbush, mature several weeks sooner than other cultivars. Usually, the varieties with larger fruit take the longest to grow.

In general, most types of butternut squash are ready to harvest between 75 and 120 days from planting seeds. Review the seed packet or plant label for specifications about the variety you’re growing.

If you transplanted nursery-grown seedlings, subtract three weeks from the days to harvest. Other factors that affect the harvest time for butternut squash are the climate, weather patterns, and other localized environmental variables.

If your area experiences an unseasonably cool or wet summer, the squash plants may take longer to reach full size. On the other hand, perfect conditions might produce a faster harvest.

Optimal Growing Conditions for Butternut Squash

Butternut squash plants are amazingly easy to grow when planted in a location with ideal growing conditions. They require full sun, meaning six or more hours of direct sunlight each day.

In especially hot climates or at high elevations, providing protection from the intense afternoon sun is helpful.

On average, butternut squash plants need approximately one inch of water per week. During periods of dry or hot weather, give them a little extra water. However, be careful not to overwater and make sure your soil has good drainage.

If the root system stays wet for too long, it cannot absorb nutrients and oxygen from the soil, and the risk of root rot and fungal disease increases.

Butternut squash plants have shallow roots and suffer when competing with weeds for water and nutrients. Take care not to disturb the squash roots or damage the delicate vines when weeding.

Use organic material like bark mulch, grass clippings, leaves, or pine needles around the base of your squash plants to insulate the soil, retain moisture, and minimize weed growth.

Harvesting and Storing Butternut Squash

Like most other types of winter squash, butternut squash is ready to harvest in early to mid-autumn, usually from late September into October. It’s important to be able to tell when butternut squash is ripe.

Immature butternut squash has a pale green rind that turns golden when ripe. The rind should begin to dry out and toughen. If you can pierce it with your fingernail, it’s not ripe yet.

Allow the stems and leaves to fully die back before harvesting your butternut squash. Be sure to gather your winter squash on a dry day before the first frost for the best storage results.

Use a sterile, sharp pair of pruners to cut the butternut squash stem a few inches above the fruit. Take care not to damage the squash rind or stem, as any exposed flesh is at risk for contamination and rot. Carry the squash by the bottom rather than the stem to avoid breakage.

Winter squash must be cured before storage, a process that hardens the rind and seals out bacteria and fungi. If weather conditions allow, leave your butternut squash on the vine to cure.

If your autumn weather is turning cold and rainy, cure them indoors in a warm, dry place for around two weeks.

Before storing them, dip each squash in a bleach solution of a half-cup of bleach to five cups of water to eliminate any remaining contaminants. Allow them to air-dry, then store your butternut squash in a dark, cool, dry place for up to three months.

When you preserve butternut squash, store peeled butternut squash tightly covered in your refrigerator for up to five days. Canning and freezing are excellent ways to extend the shelf life of your homegrown butternut squash, too.

Whether you freeze yellow squash or butternut squash, use frozen squash within one year for the best flavor.

Solutions for Common Pest and Disease Issues

Although butternut squash plants are generally simple to care for, it’s crucial to monitor your plants for any signs of pest and disease problems.

Healthy plants are much more resistant to attacks from insects and pathogens. Providing your plants with sufficient amounts of light, nutrients, and water is the best defense.

Aphids, cucumber beetles, and squash bugs are the most prevalent insects that damage squash plants. Prevent insects from laying eggs on tender seedlings by applying row covers in early spring.

Throughout the spring and early summer, check the undersides of the leaves for eggs and remove them with a damp cloth. When you catch the first signs of a pest infestation, spray all parts of the plants with an organic insecticide like neem oil or insecticidal soap.

Squash plants are often prone to fungal diseases like leaf spot and powdery mildew. These fungi persist in warm, damp conditions and often spread through water droplets.

Ensure proper air circulation and utilize a soaker hose or drip irrigation to keep the leaves dry when watering. It’s also helpful to water in the morning so the plants can dry during the day. Treat affected plants with an organic copper or sulfur fungicide.

Companion Plants for Butternut Squash

Companion planting is a time-honored garden design technique that pairs compatible plants to utilize their mutually beneficial qualities.

Certain plants attract pollinators and predatory insects, repel unwanted pests, and improve their neighbors’ flavor and overall growth. However, some other plants are not compatible and must grow separately.

To assist with pollination, plant flowers and herbs near your squash plants to attract bees, butterflies, and other beneficial insects. Ideal companion plants for zucchini and other squashes include borage, calendula, chamomile, cosmos, feverfew, and oregano. Use these flowering plants as a border around your squash bed.

Since the sprawling vines take up a lot of space, tall crops like amaranth, corn, and sunflowers are best for interplanting with winter squash.

The Three Sisters is a historic Native American plant pairing of beans, corn, and squash. The beans climb up the tall corn stalks, and the squash vines spread out to act as a living mulch over the soil and suppress weeds.

Repel cucumber beetles and squash bugs with bee balm, catnip, chives, garlic, marigolds, mint, nasturtiums, radishes, and tansy. Plants like alyssum, dill, parsley, and yarrow attract predatory insects like hoverflies, ladybugs, lacewings, and parasitic wasps (which don’t sting humans).

Growing butternut squash in your garden is astonishingly straightforward, and the rewards are well worth your efforts. All that’s required is a planting site with rich, well-draining soil, full sun, and consistent moisture.

If you’re wondering how long do butternut squash take to grow, the harvest time depends on which varieties you planted. In general, expect your crop of butternut squash to be ready in late September or early October.

We hope you enjoyed these gardening tips and would appreciate it if you share this article about how to grow butternut squash with your fellow green thumbs on Facebook and Pinterest.