What you need to know.
Plant one zucchini. I cannot stress this enough. My first year I planted four. By August I was leaving zucchini on neighbors' porches anonymously because we could not give them away fast enough. One healthy zucchini plant in Zone 7b will produce more than most families can eat. One plant. Maybe two if you want to be ambitious.
I grow Black Beauty (the classic dark green zucchini) and sometimes Costata Romanesco (an Italian heirloom with ridged skin and nuttier flavor). Both are prolific. The only variety I would avoid for NC is any yellow crookneck — they tend to have more disease problems in our humid summers. Stick to straight green types or try a round globe variety like Eight Ball for something different.
"Four zucchini plants in August. I do not want to talk about it. Plant one. Maybe two."
Step by step.
Direct sow 2 to 3 seeds per spot, 1 inch deep, after the last frost when soil is above 65 degrees — late April to early May in Zone 7b. Once seedlings are a few inches tall, thin to the strongest one per spot. Zucchini hates being transplanted, so direct seeding is always better.
Zucchini has separate male and female flowers. Male flowers (straight stem) come first. Female flowers (tiny zucchini at the base) come a week or two later. If female flowers drop without developing into fruit, hand-pollinate: use a small paintbrush or your finger to transfer pollen from the center of a male flower to the center of a female flower.
Harvest at 6 to 8 inches long, before they get big. Check every single day once production starts — zucchini goes from perfect to enormous overnight. A 12-inch zucchini has seedy mealy flesh. A 6-inch one is tender and sweet. Pick aggressively to keep the plant producing.
When to plant in Zone 7b.
Plant in late April or early May in Zone 7b. Production typically starts about 50 to 60 days from seed. In good conditions you will be harvesting by mid-June. A second planting in early July avoids the worst of squash vine borer season and produces well into fall.
Zucchini often stalls or dies in August from vine borers or powdery mildew. A second planting that goes in July sidesteps the worst of both problems and gives you fresh fall production when the first planting is done.
Problems I ran into.
Squash vine borers are the biggest problem in NC and they are devastating. The adult moth lays eggs at the base of zucchini stems in June and July. The larvae bore into the stem and kill the plant from the inside. Signs: sudden wilting on a hot day even with moist soil, and frass (greenish sawdust) at the base of the stem. Prevention is better than cure: row covers early in the season keep adults from laying eggs. Remove covers once female flowers open for pollination.
Powdery mildew covers leaves in white powder in late summer, slowing the plant. It does not kill quickly but reduces production significantly. Water at soil level only and ensure good spacing for airflow. A second July planting gives you fresh, healthy plants when the first ones succumb to mildew.
What I make with it.
Zucchini picked at 6 inches and sauteed quickly in olive oil with garlic and salt is all you need. It takes 8 minutes and the result is completely different from grocery store zucchini, which is often picked too big and sits in a truck for days.
Zucchini bread is the classic use for any that get too big. I also slice them thin on a mandoline and layer them in a gratin with tomatoes and herbs. Browse the recipes page for what I cook with the zucchini surplus.