Summer squashes (Cucurbita pepo) are warm-season annuals in the Cucurbitaceae family, which includes cucumbers, melons, winter squash, and gourds. Commonly grown types include:
- Specialty types can be scalloped, round or pale green.
Soil Nutrients and Requirements
Plants need loose, fertile, well drained soil with plenty of nitrogen and a pH 5.8-6.8. Fertilize seedlings with fish emulsion if leaves yellow.
When to Sow
Days to maturity are from direct seeding, subtract 2 weeks if transplanting. Direct seed as soon as chance of all frost has passed or start transplants 3-4 weeks before planting date. Optimum soil temperature for germination is about 85ºF and little or no germination occurs below 60ºF. Harden off plants by reducing temperature, water, and fertilizer. Many growers plant multiple successions of summer squash during a season to ensure continuous harvest, transplanting the first succession immediately after frost-free day and the final succession three months before the expected first frost.
Black plastic mulch and floating row cover can be used to increase soil and air temperature, as well as ward off cucumber beetles which feast on young seedlings and also spread disease.
Best quality fruit are harvested at 5 – 8” or smaller, while skin is soft and somewhat glossy. Harvest fruits every other day to for best size and quality and to maintain plants’ productivity.
Fruits are very perishable, but will store 3 to 4 days at 35 – 40ºF and 90% relative humidity.
- Striped Cucumber beetle feeding can damage young leaves so extensively that plants either die or are stunted in growth. Dipping or spraying seedlings with kaolin clay can significantly deter infestations. Combine clay with insecticidal soap (such as Safer Brand™, see Supplies) or neem (such as Ahimsa Neem Oil). Use of a trap crop preferred by cucumber beetles, such as blue hubbard squash, lures beetles away from main crop. Crop rotation, removal of crop debris to discourage overwintering populations, and use of floating row cover can be effective in controlling cucumber beetles.
- Squash vine borer will cause plants to look wilted even when moisture is plentiful. Slice open stem and remove and destroy.
- Squash bugs can be controlled by handpicking. Bury or compost plant residues at the end of the season.
- Powdery mildew can be checked by providing good air circulation. Give plants wide spacing and eliminate weeds, especially milkweed, marshcress and yellowrocket. Choose resistant varieties.
- Fruit rots such as anthracnose, scab, and fusarium fruit rot are common under wet conditions. Space plants apart, avoid wetting foliage and water early in the day so that leaves can dry.
- Fusarium Wilt is caused by the fungus Fusarium oxysporum f. sp. Melonis (Fom), and can be seed and/or soil borne.
- Bacterial Wilt and Cucumber mosaic virus should be controlled by removing and destroying infected plants.