Growing Butternut Squash Guide | Everything You Need to Know

Growing Butternut Squash Guide

What is Butternut Squash?

This variety of winter squash, Cucurbita moschata, has dense, sweet orange flesh and a thin skin that makes preparing this squash simple and easy.

Originally from central and South America, this squash can now be found all over the world. The flesh can be roasted, added to soups and casseroles, used in salads and risottos, and even turned into a dessert!

It’s healthy too, as it’s low in calories, high in vitamin A, E and C, rich in magnesium and potassium, and is a good source of dietary fiber, trace elements, folate and manganese.

As a result, it’s a great addition to a healthy, balanced diet, helping to reduce heart disease, cancer, and even mental decline.

How to Grow Butternut Squash

• Climate – These vegetables will grow in almost any climate, but grow especially well in Zones 2-11. Planting butternut squash should take place when temperatures are between 60—65 degrees F when no further freezing is expected.
• Sunshine – They need plenty of exposure to full sun and can tolerate the heat well.
• Soil type – The preferred soil type is a rich, well-draining soil that has plenty of compost and nutrients and a pH of 5.5 to 7 (acidic to neutral).
• Water – Water regularly but do not let the plants get waterlogged. It’s best to water the ground directly and avoid getting the leaves wet, as this can encourage fungus and disease. Drip irrigation works very well for butternut squash.
• Fertilizer – These are very hungry plants, and they need consistent feeding through the season. Start with a very rich soil base that has a lot of compost and organic matter.
  
  Add more compost in mid-summer. Use a liquid or granular fertilizer every 2-3 weeks. The best fertilizer for butternut squash is one high in potassium and phosphorus, like a 5-10-10.
• Season – Plant in early spring to allow the vines to reach full maturity and develop plenty of yellow flowers in the summer. Harvest in the fall or early winter.
• Size – Butternut squash vines have a height of 9-18 inches and a spread of up to 15 feet, so you need plenty of space for the plant to grow. As a result, it’s not a good option for small gardens or container planting.

How to Plant Butternut Squash?

How to Plant Butternut Squash Seeds

Planting Butternut Squash Indoors 

(Best for colder zones with a high risk of late frosts)

Here are the steps for planting butternut squash seeds indoors.

• Fill a 3-inch pot with prepared soil (this should be rich in compost and well-draining) in April.
• Place 2 seeds in each pot about a 1/2 inch deep and lightly cover with the soil. You can use seeds from your garden center or simply keep some raw seeds aside from a fresh butternut.
• Keep the pots moist and place them on a sunny windowsill. If two seedlings start sprouting at the same time, select the healthiest seedling and pinch out the other.
• Start the hardening off process (essentially acclimating the seedlings to the outdoor environment) by placing them outdoors in the sun during the day on warmer days and bringing them indoors at night.
  
  Keep the soil moist. Gradually increase the hours the plants are outside each day, remembering to bring them inside if any frost is predicted.
• Plant in prepared beds with seedlings spaces about 6 inches apart once the temperature reaches 65 degrees F in May. You can thin out your seedlings when they reach about 6 inches tall, giving the strongest plants more space to grow.

Growing Butternut Squash Outdoors

(Best for areas with mild spring temperatures)

Here’s how to plant butternut seeds outdoors.

• Start by preparing the beds, adding plenty of compost and organic matter so that the soil is rich in nutrients. You can create hills about 18 inches high if you prefer this method, but it is not necessary.
• Make small holes about 6 inches apart and plant two seeds in each hole, about a ½ inch deep. Cover lightly with soil and water regularly to keep the soil moist.
• You can thin out your seedlings when they reach about 6 inches tall, giving the strongest plants more space to grow.

Always Water Butternut Squash

Butternut squash thrives in hot summer weather, but it needs plenty of water to do so. Too little water can lead to low flower production and a stunted harvest.

Water regularly, especially if you are expecting a heat wave or the plants are very young. They have a shallow root system, so aim to soak the first 4 inches of soil once or twice a week.

If you see the leaves drooping, more water is needed.

Is Butternut Squash Frost Hardy?

No. The squash can handle cold weather, but will be damaged or destroyed by freezing temperatures. If you are worried about frost damage or want to make sure your seedlings get a strong head start on the growing season.

Start them off inside and slowly start acclimating them to the outdoor environment for a few hours each day, bringing them indoors at night or during cold snaps. 

Does Butternut Squash Need to Climb?

No, this type of squash happily grows along the ground, and the fruits are simply too heavy for most vertical growing systems. You will need around 10-15 feet of ground space for mature vines.

Harvesting Butternut Squash

The plants will take 110-120 days to mature, so harvest season for spring plantings will be in early to late fall.

The squash will last well on the vine, but should be harvested before the first frost of the season.

When is Butternut Squash Ready to Harvest?

They are ready for harvesting when:

• The stem where it meets the fruit starts drying out and looking brown.
• The skin is no longer shiny, turns a deep tan color and becomes a bit tougher.
• The fruit sounds hollow when you knock on it with your knuckle.

Here’s a useful guide on how to know when to pick butternut squash.

How to Harvest Butternut Squash

• Using a clean, sharp knife, cut through the stem about 2 inches away from the fruit. This avoids harming the fruit and creating an entryway for bacteria that will cause it to rot.
• Any fruits that have been damaged, cut or bruised should be eaten first as they will not store well. Very damaged fruits can be added to your compost heap. Just remember that any seeds will likely sprout!

Will Butternut Squash Ripen After Picking?

The best results come from allowing the fruit to ripen on the vine. However, if you had a very late harvest and are worried about frost, rather harvest your butternuts and try curing them indoors.

The best way to do this is to store them in a space that is 80-85 degrees F with 80% humidity for 10 days. Very unripe squash is not as tasty or sweet as vine-ripened squash, and the ones you ripen off the vine will not last as long either, so be sure to eat them first.

How to Store Butternut Squash

• Standard – The best method is to take your freshly harvested squash (no damage to the skin or stem) and store them in a dark, cool place. It will last 2-3 months.
• Refrigerator – You can store cut up or peeled butternut squash in a closed container in the refrigerator for about 4 days.
• Freezing – You can freeze cubes or slices of fresh uncooked or cooked butternut in a closed container in the freezer for as long as you like.

Pests and Diseases that Affect Butternut Squash

Butternut squash can become targets for pests and diseases, especially if they are not getting the nutrients, water and sunshine that they need.

Regularly examine your squash for aphids, armyworms, cabbage loopers, cucumber beetles and squash bugs, all of which can be treated with an insecticidal spray or soap.

Try to avoid applying any insect control during the flowering season, as this will kill bees and other beneficial insects that are fertilizing your crop.

Use organic solutions first, as these are the least damaging to the environment. One good option is companion planting with beans, corn, peas, marigolds, sunflowers, mint or nasturtium.

These squash can also become infected with fungal diseases like squash mosaic, blossom end-rot, powdery mildew, bacterial wilt and leaf spot.

To help prevent these issues, make sure your squash plants are getting enough sun and are not sitting in waterlogged soil. Treat any signs of fungus or disease with an organic or chemical treatment from your garden center.

It’s also a good idea to look for varieties of squash that are best suited to your climate, and ones that have been bred to be more disease and pest resistant.

Another good tip is to put plenty of mulch under your squash plants. This keeps the fruit off the soil, minimizing contact with fungus and bacteria. It also helps keep the soil moist.

How to Use Butternut Squash at Home

There are thousands of great recipes that use this vegetable, but here are some of our favorites to get you started!

• Roasted – This fantastic roasted butternut recipe is the perfect aide dish to any meal.
• Mashed – Mashed butternut squash is a rich, creamy and tasty alternative to potatoes.
• Stuffed – Stuffed butternut squash makes a great main or side dish.
• Salad – It’s great in lighter dishes too, and this butternut salad works well at any BBQ.
• Pasta – Butternut squash adds sweetness and nuttiness to pasta dishes, and goes well with sage and cheese, as you can see in this ravioli recipe.
• Soup – One of the easiest, most fool-proof recipes that are perfect for fall or winter is this classic, creamy butternut soup.