True zucchinis are evenly narrow along their length, and they are long - never round. We include summer pumpkins here as "round zucchinis" because they are so similar in growth habit and usefulness. Zucchinis that develop a bulbous end where the seed cavity forms, are referred to as Cocozelle types. At the end of the day, all are very productive summer squash.
Season & Zone
Season: Warm season
Exposure: Full sun
Direct sow or transplant in late May or early June when soil is warm. For transplants, start seeds indoors during the first two weeks of May. Optimal soil temperature for germination: 25-35°C (68-95°F). Seeds should sprout in 7-14 days.
Sow seeds 2cm (1") deep. Sow 3 seeds in each spot you want a plant to grow and thin to the strongest one. Aim to space zucchinis no less than 45-60cm (18-24") apart in rows 90-120cm (36-48") apart.
Ideal pH: 6.0-6.8. These big, fast-growing plants need plenty of moisture and lots of food. Grow them in rich, well-drained soil in full sun. Dig finished compost or well-rotted manure into the beds, and dig in 1 cup of complete organic fertilizer beneath each transplant. Water the soil around them when you irrigate, and always avoid overhead watering, as wet leaves will attract diseases like mildew. Keep weeded. Misshapen or withered fruits can result from incomplete pollination. Make sure to remove these from the plants as you see them, before they begin to rot, and put them in the compost.
In the home garden it can be tempting to over-plant zucchinis. One well-grown plant will provide enough fruits for the average family. Instead of planting several zuccinis, use that space for other vegetables.
Pick regularly to encourage the plant to keep on fruiting. Zucchini leaves are often very prickly, so pull delicate skinned fruit out carefully. Fully mature zucchini have a hard skin: chickens like them.
In optimal conditions at least 80% of seeds will germinate. Usual seed life: 2 years. Per 100' row: 180 seeds, per acre: 15M seeds.
Diseases & Pests
Zucchinis that are grown in good soil in full sun will have few problems. One common complaint is the development of powdery mildew on the leaves. This begins to show up in mid-summer as grey patches on the leaves and stems, and it literally is mildew. It results from excess moisture, and can be prevented or minimized by avoiding overhead watering at all times. Try to water plants early in the day, and only water the soil around them. Avoid over-crowding plants to improve air circulation around them. Leaves that are badly affected by mildew can be removed, but throw them in the garbage, not the compost.