Butternut Squash

Plant of the Week October 3, 2022

Butternut squash (Cucurbita moschata)
Written By: Lynne Forbragd, Anoka County Master Gardener

There is nothing better than the wonderful smell of butternut squash baking in the oven on a chilly night. Known as winter squash, it has a sweet and nutty flavor. Often it is used in soups or roasted for a variety of sweet and savory dishes. 

Butternut squash is easy to grow. Sow directly by seed in the spring after the danger of frost. Plant five or six seeds in a soil mound and thin to three per hill. Soil temperatures around 60-65 degrees Fahrenheit work best for germination. It can take up to 110 days before it reaches maturity. If the length of the growing season is a concern, start seeds indoors and transplant them into the garden. Butternut squash is a tender vine plant that can grow up to 15’ long and requires a lot of space. If space is limited, train it to grow on a sturdy trellis. Squash vines need six hours of direct sun and fertile, well-drained soil with a pH of 6.0-6.8.

There are different varieties of butternut that you can grow. Waltham is the most common variety and produces four to five-pound fruit. Butter baby and butterscotch have shorter vines and smaller, one or two-pound fruit.

Butternut squash is less susceptible to the squash vine borer than other squash varieties. Common pests are the cucumber beetle, which can cause bacterial wilt. Squash bugs can also attack young vines and cause them to wilt and die back early in summer. They are less likely to bother larger plants. The buildup of bacterial scab disease in the soil occurs when planting crops each year in the same location. Make sure to rotate all crops in your garden as best practice. Minimize powdery mildew by watering at the base of the plant and providing proper spacing for air circulation. Black rot can occur during storage if the fruit is not properly cleaned and stored. 

The success of a good squash harvest is knowing when to bring the squash indoors for curing. Butternut squash is ready to harvest when it has a uniform tan color, hard skin, and is no longer growing larger. The stem connected to the squash should be brown. This means that there are no more nutrients needed for the fruit. Cut the stem back three to four inches from the fruit and leave it on for curing. Clean squash by gently rubbing off dirt or debris and wiping dry with a soft towel. Keep the squash dry and store in a cool dark room 50-55 degrees Fahrenheit on a rack and well-spaced for air circulation. Squash will sweeten the longer it cures which can be around two months. Butternut squash will last up to six months and is great comfort food in the middle of winter.