It seems odd to think about pumpkins in May, but if you’re located in the northern United States pumpkin season is just starting. My daughter and I plant varieties that will be used to make jack-o-lanterns in the fall, but you can also plant pumpkins used to make pumpkin butter, pies, custard, bread, cookies and soup.
When to plant pumpkins
Pumpkins are a warm-season vegetable, meaning their seeds don’t germinate in cold soil and their seedlings are easily injured by frost. You shouldn’t plant your pumpkins until the danger of frost has passed and the soil is thoroughly warmed. In northern locations, late May is ideal, but pumpkins can be planted into early July in extremely southern sites.
Planting preferences of pumpkin varieties
Vining pumpkins. For vining pumpkins, plant your rows 10-15 feet apart and space the hills within the rows 5-6 feet apart. Within each hill, plant four or five seeds 1 inch deep. Once the plants are established, thin each hill to two or three plants.
Semi-bush pumpkins. The rows for semi-bush varieties should be spaced 8 feet apart. The hills within the rows need to be spaced at least 4 feet apart. Four or five seeds should be planted 1 inch deep in each hill. Once established, thin to the best two plants per hill.
Miniature pumpkins. Miniature pumpkin rows only need to be spaced 6-8 feet apart with hills separated by two feet. Plant two to three miniature pumpkin seeds 1 inch deep in each hill. Then thin to the best plant every 2 feet after the seedlings develop their first true leaves.
Bush pumpkins. Bush varieties should be planted in rows that are 4-6 feet apart. Plant seeds 1 inch deep at a rate of one to two seeds per foot. Then thin to one plant every three feet.
Giant pumpkins. Plant rows at least 15 feet apart and space the hills within the rows about 10 feet apart. Jumbo varieties need at least 150 square feet per hill. Plant four or five seeds 1 inch deep in each hill. Then thin to the best plant per hill. When the plants start to bloom remove the first two or three female flowers (the large ones), so the plants grow larger with more leaf surface before setting fruit. Next, allow only one fruit to develop and remove all the female flowers that develop after this fruit has set on the plant. Don’t let the vines root down near the developing fruit. Jumbo varieties develop so quickly and so large that they may break away from the vine as they expand if it is anchored to the ground.
Caring for pumpkins
High fertility, good insect control and shallow cultivation are the keys to pumpkin-growing success.
Fertilizer. Pumpkins need to be planted in soils with low nitrogen, high potassium and high phosphorus. Before planting seeds, apply a tablespoon or two per hill of 4-8-5 or 6-10-10 fertilizer.
Weeding. Plants should be kept free of weeds by hoeing and shallow cultivation.
Water. Pumpkins tolerate short periods of dry weather well but will need to be watered during extended dry periods.
Insecticides, fungicides and pollinators. You may want to use insecticides or fungicides to control common pests such as powdery mildew, cucumber beetles or squash bugs. However, if they aren’t applied properly, these chemicals can be harmful or deadly to bees that are needed for pollinating your pumpkin plants. They should only be applied from late afternoon to early evening when the pumpkin blossoms have closed for the day and bees are no longer visiting them. When the blossoms open in the morning bees will only land on the inside of them, which means they will be safe from contact with the insecticides or fungicides.
Harvest your pumpkins when they are a deep, solid color and the rind is hard. If the vines are healthy all season, you can harvest your pumpkins from late September to early October, before heavy frosts. If the vines die before the end of the season, harvest any healthy mature fruit and store it in a dry place where the temperature is between 50 and 55 F.
Cutting pumpkins from vines. To ensure your pumpkins last longer after they are harvested, use pruning shears or a sharp knife to cut them from the vines, leaving 3-4 inches of stem attached to the pumpkin. Pumpkins without stems don’t last long. You also want to try to avoid bruising or cutting the rinds of your pumpkins at harvest to ensure longevity.