Start your Broccoli seeds indoors in potting soil, 4 to 6 weeks before the last expected soil frost, at a depth of 1 inch. When your seedlings reach about 6 inches, plant them in the garden at 12 or 24 inches apart, in full sun, in rich and well-drained soil. If cold threatens for several consecutive days, cover your plants. If they become too heavy as they grow, provide support.
Avoid overwetting the leaves; excessive watering will promote mold development. Mulch the base of your broccoli plants to retain moisture in the soil.
Harvest the main head while it is still tight and before it begins to yellow; leave at least 4 inches below the flower when cutting it. The side shoots will continue to grow and can also be harvested; the plant will continue to grow as long as the temperature allows.
