When to Plant Butternuts

Spring Planting

• Butternut squash varieties don't tolerate cold temperatures, so wait to plant them until at least one week after the last frost. They germinate best when soil temperatures range between 65 and 95 degrees. A sheet of black plastic mulch laid tightly over the ground warms the soil so you can plant the seeds up to two weeks earlier. Cover the ground with a floating row cover to warm the growing area even more.

Starting Indoors

• If you live in an area with a short growing season, you might want to start butternut seeds indoors. Start the seeds three to four weeks before the last frost. They should be planted in peat pots or a seed starting tray, in a light, soil-less starting mix. Storing them on top of a refrigerator or adding a commercial plant heating blanket underneath them keeps them warm so they germinate faster. Mist them frequently with a spray bottle filled with water and move them to a sunny location or place them under grow lights once the seeds germinate. Butternut squash don't transplant well because their shallow roots are prone to damage during transplanting. Planting them in peat pots so you don't have to disturb the roots during transplanting and setting them out while they're small increase your odds of success. Start them no more than four weeks before the last frost.

Summer Planting

• Gardeners living in U.S. Department of Agriculture plant hardiness zones 6 and warmer can plant a second crop for a late fall harvest. Plant the squash no later than 14 weeks before the average first fall frost so they mature in time. In the summer, the soil is usually dry and warm. Seeds can be planted slightly deeper than you'd plant them in the spring, which keeps them moist.

Growing Tips

• No matter when you plant them, butternut squash thrive in an area that gets at least six to eight hours of sunlight daily. Most varieties grow on long, rambling vines that stretch at least 6 feet.The young seedlings should be thinned when they stand 3 inches tall. If planted in hills, space the hills 3 feet apart and leave three plants on each hill. For rows, the plants should be spaced 18 to 36 inches apart. Butternut squash plants need consistent moisture from planting time until the fruits are almost mature. Water them at least weekly, or as needed to keep the soil moist 1 inch beneath the surface. Before planting, amend the soil with 2 inches of compost and 4 cups 10-10-10 fertilizer per 100 square feet of garden space. After the plants start producing vines, a second application of 21-0-0 fertilizer applied at a rate of 2 tablespoons per plant will promote vigorous growth.