Stephen Albert
Broccoli is cool-season annual commonly treated as a two-season crop with spring and late summer planting. Broccoli seedlings are usually transplanted to the garden after being started indoors. Seeds are sown indoors or in a cold frame 5 to 6 weeks before they are set in the garden.
In spring, give broccoli an early start so that greenheads can form before hot weather arrives. Broccoli seedlings can be set in the garden up to a month before your last expected frost. Broccoli can withstand frost down to about 25°F (-4°C). It grows best at 60°F to 65°F (16°-18°C).
Broccoli is adapted to widely different soils as long as they are fertile, with good texture, and moist. Adding aged compost to the planting bed and turning it under is a good way to prepare a planting bed for broccoli.
Side dress broccoli with aged compost and a slow-release organic fertilizer at planting time will meet broccoli’s initial nutrient needs. Continue to apply these lightly around the plants at 3-week intervals.
Broccoli planting dates for spring and summer harvests*
| Average date of the last frost | Planting dates |
| Jan. 30 | Jan. 1-30 |
| Feb. 8 | Jan. 1-30 |
| Feb. 18 | Jan. 15-Feb. 15 |
| Feb. 28 | Feb. 1-Mar. 1 |
| Mar. 10 | Feb. 15-Mar. 15 |
| Mar. 20 | Feb. 15-Mar. 15 |
| Mar. 30 | Mar. 1-20 |
| Apr. 10 | Mar 15-Apr. 15 |
| Apr. 20 | Mar 25-Apr. 20 |
| Apr. 30 | Apr. 1- May 1 |
| May 10 | Apr. 15-June 1 |
| May 20 | May 1-June 15 |
| May 30 | May 1-June 15 |
| June 10 | May 10-June 10 |
| June 10 | May 20-June 10 |
Broccoli planting details
- Sowing depth: ¼ inch (.6 cm)
- Space between plant after thinning: 18-24 inches (45-61cm); broccoli plants spaced closer will have smaller heads.
- Days to sprout: 10; start seed indoors 4 to 6 weeks before setting transplants in the garden
- Days to harvest: 60-80
- Storage period: 1-2 weeks
- Seeds per 100 row feet: 1 packet
- Yield per 100 row feet: 50 pounds (45 kilos)
- Suggested varieties: Green Comet, Calabrese, Waltham 29
- Notes: Make an early to mid-summer directly in the garden if you want new plants for fall eating. Failure to produce can be caused by hot weather, lack of water, and low soil calcium.
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