key growing information

Growing Yellow Summer Squash From Seed

How to grow summer squash and zucchini: soil, row covers, spacing, seeding rates, succession planting, diseases, harvesting fruit and blossoms, storage and seed counts.

By Hensley’s Seed Co. September 3, 2026

Summer Squash - Key Growing Information

Several varieties of summer squash being harvested from the field for evaluation.

SCIENTIFIC NAME:

Cucurbita pepo

CULTURE:

Summer squash does best in fertile, well-drained soil with a pH of 5.8–6.8. Plastic mulch and fabric row covers (AG-19 weight) help young plants get going and keep insects off seedlings. Take the covers off when flowering starts so bees can reach the blossoms; misshapen or aborted fruit is often a sign that pollination fell short.

DAYS TO MATURITY:

Counted from direct sowing; take off about 14 days for transplants.

PLANT SPACING:

Set plants 18–24" apart in rows 6' apart; wider spacing can make picking easier.

AVG. DIRECT SEEDING RATE:

At 3 seeds per foot in 6' rows: 250 seeds sow about 83', 500 about 166', and 1,000 about 333'.SUCCESSION PLANTING: For the best-quality fruit, you may need to replant every 2–3 weeks.

INSECT PESTS AND DISEASE:

Powdery mildew, downy mildew, bacterial wilt and phytophthora are the usual cucurbit diseases. Good drainage, airflow, insect control and crop rotation prevent most problems; if needed, ask your local Cooperative Extension office about control options.

HARVEST FRUIT:

With some varieties, the first fruits are often misshapen, shriveled or blackened, a sign of poor pollination that usually clears up as more male flowers open. Once plants start bearing, pick 2–3 times a week, cutting or gently twisting off fruit at the size you want: zucchini at 6–8" long, yellow summer squash at 4–6", and pattypan and round types at 2–3" across. Handle gently so the skins don't scratch.

HARVEST BLOSSOMS:

Pick male flowers (thin stems) or female flowers (thick stems with a tiny fruit at the base) in mid to late morning when fully open, clipping 1–2" below the flower. If you also want fruit from the same plants, take only male flowers and leave some to pollinate the females.

STORAGE:

Keeps up to 2 weeks at 40–50°F (4–10°C) and 95% relative humidity, but is best used as soon as possible.

SEEDS/LB. (AVG.):

Zucchini about 3,400; yellow summer squash about 5,500; specialty types about 4,500.

PACKET:

25 seeds per packet unless noted, enough for about 8'.