Growing Butternut Squash

Butternut squash (Cucurbita mo is a type of winter squash with a hard exterior shell and seeds. Native to the Americas, butternut squash has been cultivated for 6,000 years. It is closely related to the pumpkin with a vine that grows along the ground. Butternut squash has tan skin with an oblong shape and a thinner waist.

How to Care for Butternut Squash

Butternut squash is cared for much like other winter squash. It can be trained to grow on a trellis to save garden space. Here are the particulars to growing the best butternut squash.

Light 

Butternut squash requires at least six hours of sun. However, the squash prefers eight hours of sunlight a day.

Soil 

Plant in well-draining soil rich in organic matter. Work compost into the top six inches of soil before planting to improve the drainage.

Planting

Plant after the soil warms and all danger of frost has passed. You can plant the squash on a hill about two inches tall and three to four feet in diameter. Put four seeds an inch deep and eight inches apart. Space the hills about six feet apart. The seeds should germinate in seven to ten days. When the seedlings have their first true leaves, pinch the weakest seeds off at the soil line so there is only two vines per hill.

Water 

Butternut squash needs a lot of water. Water an inch of water a week all at once. Place the water at the base of the plant, so the leaves do not get wet. Moisture meters are inexpensive and help you keep the soil moist but not soggy. Let the surface of the soil just dry out between waterings.

Fertilizer 

Butternut squash are heavy feeders. Fertilizer that is at least half slow release into the top three inches of the soil before planting the squash. Side dress (place beside the plants) fertilizer when the fruit starts to form. Make sure you water in the fertilizer in both cases, as it needs water to activate it.

Weeds

Weeds take sunlight, nutrients, and water from your plants. Remove them as soon as the weed emerges from the soil. Be careful when weeding not to damage the butternut squash’s roots.

Mulch

When the seedlings are six inches tall, place three inches of mulch around them. The mulch helps prevent weeds, retains moisture, keeps the soil cooler in extreme heat, and keeps the squash out of the dirt.

Diseases

Butternut squash suffers from several diseases.

Downy Mildew

Downy mildew causes yellow to ton the squash’s leaves. These spots occur between the veins on the leaves. There may be brown on the undersides of the spots. If the weather is wet, you may see a gray to purplish mold on the bottom of the leaf. Downy mildew can not only kill the leaves on your squash, but it can also kill the plant. By the time the symptoms appear, that squash plant may be doomed. Use a fungicide containing copper or sulfur on the plants around it to prevent the spread of the mildew. You can also use horticultural oils, but these can cause phytotoxicity at high temperatures.

Powdery Mildew

Powdery mildew looks like a white powder covering the leaves of your butternut squash plant. It thrives in hot, dry conditions. Some horticultural oils control it.

Root Rot

Root rot is caused almost exclusively by overwatering and poor drainage. Reduce watering, so the soil dries on top before you water it again.

Viruses

Viruses cause a range of symptoms:

• Stunted growth
• Twisted or distorted leaves, flowers, and stems
• Discoloration of the leaves such as yellow mottling and mosaic patterns, ring spots, and dark-green banding
• Symptoms start in the leaves, then spread
• Spread by pests or dirty tools
• Systemic and get worse as the plant grows

Viruses are not curable. Remove the squash plant and throw it in the trash, not the compost pile.

Pests 

Several pests eat squash plants and fruit. Here are the most common.

Squash Bug

Squash bugs are gray to brown insects with alternate light and dark lines on the abdomen. The eggs are bronze and shiny. Nymphs start green with black legs. Over the five molts it takes for the nymphs to become adults, they get darker gray. Their legs remain black. Feeding leaves white spots. The leaves will become tattered looking when they have a heavy infestation. They will eventually turn yellow and die.

Squash Beetle

These beetles resemble a ladybug (also a beetle) but are tannish orange with fourteen black spots. They lay yellow eggs in clusters on the underside of the leaves. The larva is yellow with spikes; some tipped with black on them. The larva feeds on the leaf between the veins.

Squash Vine Borer

The adult squash vine borer is a fat, a black clear-winged moth with orange legs and an orange and black abdomen. The adult mimics a wasp. The eggs are tiny and laid singly. The larva, which causes the most problems, is a white to cream caterpillar with a black head. When the eggs hatch, the caterpillar bores into the stem of the squash. It eats the inside and pushes the frase out of the entrance hole. The runner or entire vine wilts quickly and dies as the caterpillar eats the flesh inside the stem.

Treating Pest Problems

Hand-picking most pests off of the squash plants works well. Drop the pests in a jar of soapy water, and they will drown. Look at the undersides of the leaves and squash any eggs you find.

If chemical control is necessary, pyrethrum and neem oil are both allowed in organic gardening. Be careful to read the label and follow directions. Spray in the evening when you are less likely to get them on bees. Pyrethrum is toxic to beneficial insects as well as pests. Neem oil is toxic when eaten, so it doesn’t affect bees and other pollinators.

Butternut squash is somewhat resistant to the squash vine borer. Pyrethrums sprayed on the lower stem will kill the caterpillar as it crawls from the egg to the stem. Once it is in the stem, you can inject Bacillus thuringiensis (Bt) into the entrance wound.

Preventing Disease and Pest Problems

You can prevent most pest and disease problems. Here are some tips to keep your butternut squash healthy.

• Remove dead and spent plants
• Plant disease-resistant cultivars
• Use seeds that are certified disease free
• Inspect your plants every three to four days for problems. Catching pests and diseases early increases your chances of managing them.
• Do not get water on the leaves of the squash

Other Problems

Pollination Problems

Butternut squash produces both male and female flowers. The female flowers have a small squash at the base. Squash commonly produces male flowers first, then female flowers. The male flowers will fall off without producing fruit. Bees and other insects move the pollen from the male flowers to the female flowers. Pesticides or damp, rainy days can keep these insects from doing that. Squash flowers that are not pollinated drop off, along with the fruit at their base. If the flower is partially pollinated, the fruit will often be deformed.

You can hand-pollinate squash plants. Choose a male flower and pick it. Carefully peel the petals back, exposing the pollen. Brush the pollen into a female flower, getting it on the parts sticking out of the center. One male flower can pollinate about five female flowers.

Harvest

Butternut squash is ready to harvest about 70-80 days from planting. If a fingernail scraped across the squash does not make a dent, and the rind is hard, the squash is ready. Cut the stem off two inches above the squash. Trying to pull the squash off will injure the vine. Let the squash cure for a day or two in a cool, dark place. Store the squash at a temperature of 50-55 degrees. Make sure the squash do not touch each other when being stored.

One-half cup of ripe butternut squash will provide half the daily requirement for vitamin A.