Age-Old Wisdom meets Modern Tools
Planting, Growing, and Harvesting Summer and Winter Squash
Squash, especially zucchini, are very prolific producers! Easy to grow, each plant will produce several squash a day during peak season. Make sure you harvest summer squash when tender and still immature!
Squash are generally divided into two categories based on when they’re harvested and how they’re used:
Summer squash are harvested in the summer before they reach full maturity. Because they’re harvested early, their skin is edible and they have a relatively short shelf life. Summer squash varieties include zucchini, straightneck squash (a.k.a. “yellow summer squash”), and crookneck squash.
- Winter squash are harvested in autumn after or just before they reach full maturity. This leaves their skin inedible, but gives them a longer shelf life (some varieties are capable of keeping through the winter—hence the name “winter squash”). Winter squash varieties include pumpkins, butternut squash, spaghetti squash, and acorn squash.
Thanks to their regular bumper crops, you usually only need one or two zucchini plants—and you may still find yourself giving zucchini away to neighbors or baking lots of zucchini bread!
A Common Ancestor
Would you believe that pumpkins and zucchini come from the same species of plant? That’s right—they’re both cultivated varieties (“cultivars”) of Cucurbita pepo. Despite the great diversity of squash, most commonly-grown cultivars belong to one of three species: Cucurbita pepo, C. moschata, or C. maxima. Over generations and generations, these plants have been cultivated to produce fruit in all kinds of shapes, colors, and flavors.
When to Plant Squash
- We generally recommend direct-seeding for squash because they do not always transplant well. The soil needs to be warm (at least 60ºF/16°C at a two-inch depth), so plant summer squash after spring (cool-season) crops, like peas, lettuce, and spinach—from about one week after the last spring frost to midsummer.
- If you wish to start seeds indoors due to a short gardening season, sow 2 to 4 weeks before your last spring frost in peat pots. (See local frost dates.)
- If you do transplant, be very gentle with the roots.
- To get an early start when soil temperatures are not yet ideal, warm the soil with black plastic mulch once the soil has been prepared in early spring.
- In fact, waiting to plant a few seeds in midsummer will help avoid problems from squash vine borers and other pests and diseases common earlier in the season.
Choosing and Preparing a Planting Site
- The planting site needs to receive full sun; the soil should be moist and well-drained, but not soggy.
- Squash plants are heavy feeders. Work compost and plenty of organic matter into the soil before planting for a rich soil base. (Learn more about soil amendments and preparing soil for planting.)
- Most summer squash now come in bush varieties, which take up less space, but winter squash are vining plants that need more space. Bush varieties will need to be thinned in early stages of development to about 8 to 12 inches apart.
How to Plant Squash
- To germinate outside, use a cloche, row cover, or frame protection in cold climates for the first few weeks.
- Plant seeds about 1-inch deep and 2 to 3 feet apart in a traditional garden bed.
- Alternatively, plant as a “hill” of 3 or 4 seeds sown close together on a small mound; this is helpful in northern climates, as the soil is warmer off the ground. Allow 5 to 6 feet between hills.
How to Grow Squash
- Mulch around plants to protect shallow roots, discourage weeds, and retain moisture.
- When the first blooms appear, apply a small amount of fertilizer as a side dress application.
- If your squash blooms flowers but never bears actual fruit, or it bears fruit that stops growing when it’s very small, then it’s a pollination issue. See more about this—and how to hand pollinate your squash blossoms.
- For all types of squash, frequent and consistent watering is important for good fruit development. Water most diligently when fruits form and throughout their growth period.
- Water deeply once a week, applying at least one inch of water. Do not water shallowly; the soil needs to be moist 4 inches down.
- After harvest begins, fertilize occasionally for vigorous growth and lots of fruits.
- If your fruits are misshapen, they might not have received enough water or fertilization.
- There are a couple of challenging pests, especially the squash vine borer and the squash bug. The best solution is to get ahead of them before they arrive.
- Cucumber Beetle
- Blossom-End Rot: If the blossom ends of your squash turn black and rot, then your squash have blossom-end rot. This condition is caused by uneven soil moisture levels, often wide fluctuations between wet and dry soil. It can also be caused by calcium levels. To correct the problem, water deeply and apply a thick mulch over the soil surface to keep evaporation at a minimum. Keep the soil evenly moist like a wrung out sponge, not wet and not completely dried out.
- Stink Bug: If your squash looks distorted with a dimpled area, the stink bugs overwintered in your yard. You need to spray or dust with approved insecticides and hand pick in the morning. Clean up nearby weeds and garden debris at the end of the season to avoid this problem.
How to Harvest Squash
- Harvest summer squash when small and tender for best flavor. You may harvest as “baby squash” or when mature (6 to 8 inches long). Large squash have very little taste.
- Most varieties average 60 days to maturity, and are ready as soon as a week after flowering. (Check the seed packet for more exact information.)
- Check plants everyday for new produce. Once squash starts producing, you’ll be picking every day!
- Cut the fruit off the vine rather than breaking them off. Leave at least an inch of stem on the fruit. Use a sharp knife.
- Should you miss a picking or two, remove the overripe squash as soon as possible to reduce demands on the plants for moisture and nutrients.
- Summer squash is very susceptible to frost and heat damage, so you do want to pick them all before the first fall frosts arrive.
- Fresh summer squash can be stored in the refrigerator for up to ten days.
- Harvest winter squash when the rind is hard and deep in color, usually late September through October.
- Winter squash can be stored in a cool, dark place until needed. Many varieties will last for most of the winter (except for acorn squash, which do not keep for more than a few weeks). If you have a cool bedroom, stashing them under the bed works well. They like a temperature of about 50 to 65°F (10 to 18°C).
- Pull up the vines and compost them after you’ve picked everything or after a frost has killed them. Then till the soil to stir up the insects a bit.
- ‘Goldbar’ (yellow summer squash)
- ‘Cocozelle’ (zucchini, summer) dark green, slender
- ‘Butterbush’ (butternut, winter)
- ‘Cream of the Crop’ (acorn hybrid, winter)
Wit & Wisdom
- If you find yourself with a bumper crop, squash pickles are easy to make.
- Or, freeze your squash! Wash it, cut off the ends, and slice or cube the squash. Blanch for three minutes, then immediately immerse in cold water and drain. Pack in freezer containers and freeze. Learn more tips for freezing zucchini.
- See our Best Zucchini Recipes for ways to use this abundant crop!