Growing Zucchini, also Courgette/Marrow, Summer squash

Cucurbita pepo : Cucurbitaceae / the gourd family

Jan F M A M J J A S O N Dec
    S                  
      T                
      P P P            

(Best months for growing Zucchini in USA - Zone 5a regions)

  • S = Plant undercover in seed trays
  • T = Plant out (transplant) seedlings
  • P = Sow seed
  • Grow in seed trays, and plant out in 4-6 weeks. Sow seed at a depth approximately three times the diameter of the seed. Best planted at soil temperatures between 21°C and 35°C. (Show °F/in)
  • Space plants: 50 - 90 cm apart
  • Harvest in 6-9 weeks. Cut the fruit often to keep producing.
  • Compatible with (can grow beside): Corn, beans, nasturtiums, parsley, Silverbeet, Tomatoes
  • Avoid growing close to: Potatoes
  • a) seedlings
  • b) Six or seven weeks old
  • Zucchini flower

Plant into a slightly raised, well composted bed and mulch. Needs regular plentiful water. Produces large leaves with a spread of about 1.5 m x 1.5 m. Some varieties trail a bit but don't climb. The yellow (or gold) variety is more resistant to mould damage in humid areas and remains productive even when the leaves have mildew on them. The yellow varieties sometimes have yellow patches on their leaves but it is just colour not disease. If there are no bees around and the fruit are not setting well or die off after starting to grow, try picking a male flower (straight stem) and gently brushing pollen inside female flowers.

Blackjack is the most popular green variety. At the start, the plants produce mainly male flowers. The female ones start as the weather warms up and the plants grow. A spray with a 5 gm/teaspoon Bicarbonate of Soda in 600 ml/pint of water will help slow powdery mildew when it appears.

Culinary hints - cooking and eating Zucchini

Zucchini are best picked or cut off the stem at about 15 cm / 6 inches.
Pick frequently to keep the plant producing new flowers.

Your comments and tips

Be the first to post a question or tip from the USA

Hi Gurinder, that’s a lot of zucchinis you have…3000 plants. Based on about 10,000 plants per hectare, this is a sizable area. I do think you should seriously consider seeking serious professional advice. You may have just gone thru a period of extreme weather - heat wise or rain wise, which could have adversely affected fruit setting. Some varieties are more susceptible to this depending on whether they are open pollinated or parthenocarpic hybrids (you didn’t mention the variety so I’m only assuming this stage). So, my suggestion is just to hang in there at this stage and just harvest what you can from the plants. Re fertilizing, this is not an easy question. Ideally you would have had a soil analysis to establish a pre-plant fertilizer (NP&K) and a side-dressing fertilizing (N&K only) program, confirmed by a couple (at least one) leaf tissue analysis about first flowering and maybe half way thru the fruiting season. In lieu of all this you could have given a basal pre-plant dressing of 800-1200 kg/ha of low analysis 5:5:5 or 300-400 kg/ha of high analysis 14:14:14 fertlizer, (or something close to this NPK ratio); followed up by side dressings from first flowering with fertilizers containing only nitrogen and potash (no phosphate). Some growers alternate light dressings (30-40 kg/ha) potassium and calcium nitrate every few weeks from fist flowering. Too much nitrogen early encourages excessive foliage growth and an over-abundance of non-productive male flowers. If you did not give a good pre-plant basal dressing then I would suggest light side dressings every couple of weeks (followed by good watering) with a high analysis fertilizer, something approx to a 14:14:14 fertilizer. I hope this helps a bit. John

- John BEE

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