Winter Squash Seeds - Waltham Butternut

Different varieties of squashes take different amounts of time to grow, with winter squash taking the longest, about 3-4 months until maturity, and summer squash taking about 2-3 months to reach maturity. Squash will do best direct seeded in your garden beds, but if your season is short you can start inside 3-5 weeks before your last frost date. Find out when your 100% certain last frost date is in your grow zone to determine when you should direct seed or transplant. Squashes will not thrive in cool soil, so planting outside early offers little to no advantage. 

Choose a spot in your garden that has full-sun and well-drained soil worked with organic matter. Plant both summer and winter squash in spring once the soil temperature is above 60° at a depth of 1”. Make sure the last frost has passed. Even if the soil temperature is warm enough, a frost could damage your squash seeds. If you plant before the soil is warm enough, your squash seeds probably won’t germinate. If you start your plants indoors, be sure to harden the seedlings so they won’t shock as much when you move them outside. To harden seedlings, you slowly expose them to outdoor conditions over the week or two before you plant them outside. Move them outdoors for a short period of time each day, beginning with 1 to 2 hours and then increasing in 1-hour increments. Make sure to shield them from direct sunlight and wind.

Summer squashes are almost all bush-type and should be planted about 12” apart in rows 2-3’ apart and winter squashes are almost all vining-type and will require more space, about 4’ by 4’ square pattern. The larger your expected mature fruits are, the more space you should give the plants. Mulch around your seeds/plants to help control weeds and maintain soil moisture. Keep your seeds watered at least once a day until they germinate, which should happen in 6-12 days for most cultivars. Aim to provide the usual 1” of water or rain a week for your vegetable garden. 

For summer squash, once your plants start producing, check them for mature squash daily. Do not pick summer squash when the vine is wet, as this can cause plant disease. Avoid leaving large summer squash vegetables on the plant since this can lead to plant disease and reduced production. Ideally, you should harvest different types when crookneck and straightneck varieties are 1 1⁄2-2”in diameter, zucchini is 7-8” long, scallop types are 3-4” in diameter.
Do not pick the squash by hand as this may damage the fruit. Instead, use scissors or a paring knife to cut about 1” above the fruit. Frequent harvesting improves the overall yield and will keep the plant producing longer into the summer.

For winter squash, you want to harvest once the fruit has turned a solid color and the rind is hard. Make sure you harvest before a hard freeze, since a hard freeze will ruin the vine and destroy the fruit. When harvesting, leave at least 2” of stem, and leave more if possible. Field-cure your winter squash for a week in dry, sunny weather. If the weather is cold or rainy, cure your winter squash indoors in a well-ventilated space. Curing winter squash dries and toughens the skin, allowing for longer storage. 
Store winter squash in a dry location that is around 55°. Do not pile winter squash on top of one another, and remove any squash that show signs of damage. Squash varieties like acorn squash and striped delicata squash should be eaten a few weeks after harvest. Butternut squash should be eaten after a few months of storage. Round squashes like Blue Hubbard squash can be stored until March or April. For longer storage, cook, mash, and freeze your winter squash.

Squash, Cucurbita spp.
Pollination, insect; Life Cycle, annual; Isolation Distance, ½ mile
Squashes are an insect pollinated monoecious (male and female flowers on the same plant) annual that are very high producers of nectar, making them very attractive to pollinators, especially honeybees. There are four species of squash commonly grown in North America: C. maxima, C. argyrosperma, C. Moschata, and C. pepo. Because the four species do not cross with each other, this allows you to grow four different species in the same garden. Squash must be fully mature before harvested for seed production. This means that summer squashes must be left on the vine until the outer shell hardens. Allow to cure for an additional 3-4 weeks after harvest to encourage further seed ripening. Cut open fruits and scrape out seeds and pulp into a jar or bucket, filling with an equal amount of water. Ferment seeds for 2 to 4 days, pour off the floaters and wash the rest of the seeds clean from the wet chaff. Spread on a screen or several sheets of newspaper to dry thoroughly before storage. This could take several weeks.