Whether growing for Halloween or simply for fun, pumpkins are a rewarding crop to grow. Tuck them into garden soil in May and June for a harvest around Halloween, or plant them earlier for a smaller fruit.
Choose a sunny spot with fertile, well-draining soil and an ideal pH of 6.0 to 6.5. Dig in a generous amount of compost or aged manure to provide nutrients.
Choose the Right Seeds
The viability of pumpkin seeds is often a matter of luck, but there are several ways to test them before planting. Most seeds will remain viable for three to five years if they are properly prepared and stored–paper bags, envelopes, and cardboard boxes all work well.
When choosing seeds, look for those that offer some protection against common diseases like powdery mildew. This is particularly important if you live in a humid climate.
Since pumpkins take 75 to 100 days to mature from seeds, choose a day after the last frost to direct sow outdoors or start indoors. Each seed packet will list how long on average the pumpkin will need to reach full size (Days to Maturity). The seeds’ long sides can be gently filed with a nail file or soaked in water for an hour before planting, which helps reduce their thick coat and speeds up germination. Also, amend the soil with compost or aged manure before planting to improve drainage and supply nutrients.
Preparing the Soil
Pumpkin plants prefer full sun, but it’s important to choose a spot with well-draining soil. Before planting, amend the soil with a rich compost or manure to provide nutrients from the start. Check the soil pH level, which should be between 6 and 6.8. Weeds, including grass and weedy biennials, can compete with pumpkin plants for nutrients, so clear the area two weeks ahead of time.
Plant traditional field or jack-o-lantern pumpkin seeds into garden soil from May 15 to June 15, and miniature varieties from May 25 to July 1. Seeds have a thick coat, so it helps to file the edges of each seed lightly before sowing them to break through the shell more easily. Soak large seeds for an hour or so in warm water to promote germination. Use floating row covers to protect the young plants from insects and cold fronts, but remove them when the flowers begin forming to ensure pollination. Water deeply but sparingly, and water the base of the plant rather than the foliage to minimize mildew development.
Direct Seeding
Pumpkins grow best when planted directly into the ground after the danger of frost has passed. They prefer slightly rich, well-draining soil. Enrich the garden beds with a generous amount of composted manure or humus before planting. Dig in 1 cup of organic fertilizer beneath each pumpkin plant.
Pumpkin plants are heavy feeders. They will benefit from regular applications of a high-nitrogen fertilizer.
It can take 75-100 days for pumpkins to develop from seed. If you are planting them outdoors, count backward from the first frost date in spring (your local university coop extension service can help with this estimate). For faster germination, soak the seeds in water for about an hour before sowing them. You can also gently file the seeds’ long sides, which reduces the seed coat and speeds up germination. Pumpkin plants require wide spaces, so make sure to plant them three to five feet apart, depending on the pumpkin variety. Thin the vines as they grow to give stronger plants room to expand.
Harvesting
Whether you want to grow your own jack-o-lantern seeds or simply save some of the seeds from a pumpkin you grew this year, saving pumpkin seeds is easy. Cut open a ripe pumpkin and scoop the seeds into a colander, which you then place in running water. The water will separate the seeds from the pulp, and healthy, viable seeds will sink to the bottom while dead ones float on top. After the seeds are washed and dried, label envelopes with the kind of pumpkin they’re from.
If you plan to plant the seeds outside, acclimate them to outdoor conditions over 7-10 days before planting in late spring after the last frost date and when soil temperatures have warmed up. Pumpkins need rich, warm, well-draining soil, so dig in plenty of humus and compost in advance. Keep the plants weeded and mulched to retain soil moisture in summer heat, and fertilize with an organic slow-release product.