A cool-season annual vegetable, broccoli grows well from seeds or transplants. Broccoli seeds grow and the plants reach maturity 11 to 15 weeks after planting, and transplants mature in 8 to 12 weeks after planting.

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Harvest broccoli before the flower heads open.

Growth Time Frame

Broccoli transplants and seeds offer gardeners the chance to plant two to three weeks before the last expected spring frost because the broccoli plant grows best in cool weather. A second crop of broccoli thrives in the fall months and can be started three weeks before the first anticipated fall frost.

Best Growth

Broccoli grows and produces an ample crop when the weather does not exceed 75 degrees Fahrenheit. It can withstand low temperatures to 28 degrees F. before it suffers damage and ceases growing. A heavy drinker, broccoli requires 1 to 2 inches of water per week to grow well.

Harvest Considerations

Broccoli must be harvested before the flower heads of the plant open and seeds form. Cut the heads when they are still compact. After harvesting the first heads, continue to water and fertilize the plant to encourage it to grow side shoots for further harvest before the end of the plant's life cycle.