Summer Squash

• About 200–320 seeds/oz for yellow, patty pan and Lebanese summer squashes; 1/2 oz packet sows 5–8 hills; 1 oz, 40–60 hills. About 130–240 seeds/ oz for zucchini.
• Days to maturity are from direct seeding; subtract 20 days for transplants.

  Culture: Tender, will not survive frost. Minimum germination temperature 60°, optimal temperature range 70–90°. Sow in hills 4' apart, 5 seeds/hill. Thin to 2–3 best plants. Or start indoors, 25 days before transplanting. Immediately install wire hoops and row cover to keep out cucumber beetles. Floating row covers, especially when used in low tunnels, provide extra heat and can hasten maturity by 1 to 2 weeks. Make succession plantings to ensure harvest through the entire frost-free season, insurance against powdery mildew and other diseases of tiring old plants. For best flavor pick summer squash when they are small. Don’t leave oversized squash on the vines. It shuts down production.

  Squash blossoms are a delicacy. Harvest male blossoms when fully open for salads or stuffing. Male blossoms typically precede females by about a week. Females have a bulge at the base of the blossom, an early stage of the fruit forming.

  In early summer, a combination of cool, cloudy weather and declining bee populations may result in poor pollination causing low yields. Mites and colony collapse disorder have wiped out a high percentage of wild and domesticated honeybee colonies in the last 20 years, creating a real crisis for cucurbit growers.

  Pests & Diseases: To combat squash bugs without using pyrethrum or neem: Protect young plants with row covers. Striped cucumber beetles and squash bugs overwinter in squash residues so burn or haul these away at season’s end rather than cold composting them. By hand-picking them in June and July, I reduced an endemic problem and almost completely eliminated squash bug damage.

  • CMV: Cucumber Mosaic Virus
  • PM: Powdery Mildew
  • PRSV: Papaya Ringspot Virus
  • WMV: Watermelon Mosaic Virus
  • ZYMV: Zucchini Yellows Mosaic Virus

  Pest: Striped Cucumber Beetle
  Cultural controls: use tolerant or resistant varieties, rotate crops, till under crop debris soon after harvest, use floating row covers until flowers appear, use plastic mulch, perimeter trap cropping (Black Zucchini and Blue Hubbard make particularly good trap crops), use yellow sticky strips, hand-pick early morning when beetles are very sluggish.
  Materials: Surround, Pyrethrum (PyGanic).

  Pest: Squash Bug
  Cultural controls: rotation, till in cucurbit debris before winter and plant a cover crop, boards on soil surface near squash will attract bugs overnight which can be killed, avoid mulching. Squash bugs lay their brown-brick red egg clusters on the underside of the foliage, often next to the central vein—destroy egg clusters on undersides of leaves.
  Materials: Pyrethrum on young nymphs, AzaMax.

  Pest: Squash Vine Borer
  Cultural controls: butternut squash is resistant, maximas & pepos susceptible; rotation, plow in squash vine debris soon after harvest, use floating row covers, watch for wilting plant parts and destroy borer within.

  Disease: Powdery Mildew
  Controls: Use small plots to slow spread, plant indeterminate (viney) varieties, control weed competition.
  Materials: sulfur and whole milk, mineral or other oils in combination with potassium bicarbonate.

  Disease: Bacterial Wilt
  Cultural control: Striped Cucumber Beetle is vector—control it; choose resistant varieties.

Germination Testing

For the latest results of our germination tests, please see the germination page.