Butternut squash (Cucurbita moschata) is a plant species also known as Pennsylvania Dutch Crookneck Squash. This species is considered easy to grow in winter. Butternut squash is edible, sweet, flavorful and used for soups, stews, and pies. It will keep well if stored properly.
I. Appearance and Characteristics
Cucurbita moschata is a species originating in either Central America or northern South America. It includes cultivars known as squash or pumpkin. C. moschata cultivars are generally more tolerant of hot, humid weather than cultivars of C. maxima or C. pepo. They also generally display a greater resistance to disease and insects, especially to the squash vine borer. Commercially made pumpkin pie mix is most often made from varieties of C. moschata. The ancestral species of the genus Cucurbita were present in the Americas before the arrival of humans.
No species within the genus is fully genetically isolated from all the other species. C. moschata can be hybridized with all other species. It has been suggested that this shows that the species of Cucurbita have diversified more recently than those of related genera such as Cucumis and Citrullus.
All species of squashes and pumpkins are native to the Western Hemisphere. C. moschata, represented by such varieties as Cushaw and Winter Crookneck Squashes, and Japanese Pie and Large Cheese Pumpkins, is a long-vining plant native to Mexico and Central America. This species and C. pepo apparently originated in the same general area, Mexico and Central America. Both are important food plants of the original people of the region, ranking next to maize and beans. The flowers and the mature seeds, and the flesh of the fruit are eaten in some areas.
II. How to Grow and Care
Sun and Temperature
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. These plants will only stay alive once the danger of frost has passed and the days have reached 70 degrees Fahrenheit.
A single frost can kill even a well-established plant. During the heat of summer, excessive heat can cause the leaves to wilt during the day, be careful not to overwater as they will perk up later in the evening. They grow well in zones 3-10 but have a longer growing season the further south you get.
Water and Humidity
It’s best to water throughout the growing season once a week at the base of the vine, preferably on a drip line or soaker system. Each plant needs at least one inch of water per week during early growth and 1-2 inches once large fruit has set. Be careful not to water too often as this can lead to cracking as the plant absorbs water at a rate faster than it can create more skin. Once the squashes have tanned and are starting to dry, stop watering to further avoid cracking.
Soil
Squash needs well-draining, loamy soil as they are a shallow-rooted plant. Try to keep the soil moist but not wet, especially while the squash is still young. The plant can survive poor-quality soil but may produce fewer squashes as a result. They aren’t too picky about pH needing something in the range of 5.5-7.0. Mulch well to provide nutrients and help retain soil moisture.
Fertilizing
For the best fruits and vegetables, any type of balanced fruit and vegetable fertilizer will do the trick for butternut squash. Adding fertilizer with slightly higher levels of nitrogen will encourage peak leaf growth instead of flowers and fruits. Use fertilizer before planting your butternut squash and then every month after throughout the spring and summer.
Pruning and Training
If you plan on letting your squash roam freely in the garden, you probably will not need to train your squash much. Once a vine has 3-4 fruits, clip off the end of the vine to stop further production. The quality of the butternut squash produced can decrease if too many squash are growing on a single plant.
A way to save space in the garden is to train your squash up a trellis or arch. This is also a great way to keep the vines up off the ground, where they may come in contact with more diseases and pests. While young, train the vines up a trellis, anchoring them using string or wire. Be sure to do this while the plant is still small, as moving larger plants can result in them breaking and stunting growth. Once the butternuts form and begin to hang, give them extra support, so they don’t snap off. You can aid them by tying them up with pantyhose, old t-shirts, or kitchen towels.
How to Grow from Seed
Most gardeners purchase butternut squash seed packets (available at grocery stores, hardware stores, online, and from seed catalogs). Once you have the seeds, you can start them indoors to get a jump on the season, or you can wait until danger of frost has passed and direct-sow outdoors. Direct seeding in the garden is easier, but starting seeds indoors can be helpful to those in areas with short summers.
- To start seeds indoors, plant them about three weeks before the last frost in spring.
- Fill 3-inch biodegradable pots with potting soil, and plant two seeds in each pot. Water, and place the pots in a sunny window. Do not let the soil dry out completely.
- If both seeds in a pot germinate, select the healthiest seedling as the one to keep and pinch out the other.
- When the plant has two sets of true leaves, begin the hardening off process. On warm days, set the pots outdoors in partial sun for a few hours at a time. Bring them back indoors at night. Gradually increase the number of hours that they stay out, as well as the sun exposure. This process helps them adjust to the transition from an indoor environment to an outdoor environment.
- Plant the biodegradable pots in the ground once the soil temperature is at least 65 degrees Fahrenheit and all threat of frost has passed.
- If you choose to direct seed, simply skip to the step where you create hills and plant four or five seeds in each hill, thinning them out later.
Pests and Diseases
Common Pests & Plant Diseases
Butternut squash can be susceptible to squash bugs, which can cause leaves or whole vines to turn brown, wilt, and/or eventually die. These bugs are most active from late summer to winter. To combat this, you should remove any infected plants to prevent spread to the others. You can also spray with a mixture of warm soapy water (using dish soap). Note that there are varieties of butternut squash that are resistant to these bugs that you can choose to plant, such as ‘Royal Acorn’ and ‘Sweet Cheese’.
When the seedlings are young, they are susceptible to drought (so keep their soil moist) and to damage from slugs and snails. Be sure to take control measures against these pests. Later in the season, Japanese beetles can become a problem. Pick them off by hand and throw the beetles in a bucket of soapy water.
Butternut squash can fall victim to powdery mildew, a fungal disease that affects squash plants. Affected plants will see the mildew cover leaves, which will then turn yellow or brown, curl up, and die. To combat, plant disease-resistant varieties, plant in full sun, and adhere to proper spacing when planting.
Common Growing Issues
- Yellow, Drooping Leaves
Yellow and/or drooping leaves can be indicative of an overwatered butternut squash plant. Test the soil, and if it feels overly wet or soggy, pull back on watering until the plant recovers and a moisture-balance is restored.
- Fruit Falling Off
Butternut squash fruit can fall off the plant if the growing conditions are not met (perhaps not enough sun or too little or too much fertilizer) or if there is poor pollination. Make sure your squash is planted near a pollinator plant.
III. Types of Winter Squash
A “winter squash” is defined as a kind of squash that has a hard enough skin that it preserves well if stored in a cool place. Thus, if you were to harvest one in October, it would keep until at least December (winter) if stored in a suitable place, such as an unheated basement or root cellar.
Butternut squash is just one of several winter squashes that are commonly grown. Another popular winter squash is Hubbard squash (Cucurbita maxima), which has a gray, bumpy exterior.
In contrast to winter squashes, there are also summer squashes, such as zucchini squash (Cucurbita pepo var. cylindrica). Summer squashes have a soft skin that is edible and perish quickly.
IV. Harvesting and Storage
- Harvesting
Butternuts are ready to harvest when the stem connecting the fruit to the vine is completely dried out, and the skin of the butternut cannot be pierced with your fingernail. There are a few other hints that you can use to gauge their readiness – read about them in our separate article on when to harvest butternut squash!
Cut the stem about an inch away from the fruit and allow it to dry in the sun for about two weeks. This is a process called curing. If you plan on long-term storage, after curing, wipe down the skin with a solution of water and bleach to kill mold spores and insect eggs that can destroy your squash when stored for a long time.
- Storing
Once the butternut squash has been properly cured and cleaned, the squash can last 2-5 months at 50-60 degrees or in a well-ventilated cellar or pantry. Do not stack squash on top of one another; they need air circulation. Check regularly for rot, as one rotten squash can cause others to rot.
You can also cube the butternut squash and pressure can it using a tested and safe recipe. Freezing is also a great option; dice up your butternut and lay it on a parchment-lined baking sheet until frozen, then store in a freezer bag. It’s possible to dehydrate cooked squash as well, although the texture may be odd afterward.
