Winter Squash Seeds,
Illinois

Start seeds indoors about 3–4 weeks before the last frost, or direct sow outdoors after the soil has warmed to at least 70°F. In longer-season climates, an early summer planting is also possible. If you’re not sure how to find your first and last frost dates, consult our blog post 'Our Experts Answer Questions, Share Resources.'

Plant Illinois squash seeds 1 inch deep into fertile, loose soil. Sow seeds 48–60 inches apart, giving the long vines plenty of space to spread. Mound planting improves drainage and warms soil faster in spring. Water thoroughly after planting to support strong, even germination.

Thin seedlings to the strongest plants after sprouting. Allow vines to sprawl or gently guide the vines to your preferred spot. Keep the soil consistently moist but not waterlogged. Harvest mature squash when rinds are tough and stems begin to dry and crack near the fruit.

• There are four main species of squash: Cucurbita maxima, C. pepo, C. moschata, and C. mixta. They will not cross pollinate with each other, so it is possible to grow one of each species for seed saving without worrying about cross pollination.
• If you are planning to grow several varieties of more than one species, you can bag the blossoms and hand pollinate to avoid crossing.
• Whether it is a summer or winter squash, you must let the fruit completely mature before extracting the seeds, and cure for at least two weeks.
• Scoop the seeds, place them in a bucket, and add just enough water to cover. Let sit at room temperature to ferment for two days before rinsing off the pulp.
• Lay seeds out to dry on newspaper or paper plates.
• Stored in a cool, dry place, seeds will remain viable for up to four years