Fall harvested crops are generally more successful than summer harvested crops. Brussels sprouts improve in flavor after a light frost. Date of maturity varies, depending on variety, location, and season. Count backward from the first fall frost date to figure out the best time to start plants.
Plan to start seeds in flats or pots 4 to 6 weeks before planting in the garden, or buy nursery transplants if available. You can also sow seeds directly in the garden 4 months before the average first fall frost date.
To reduce the threat of pests and diseases, plant where other members of the cabbage family have not grown for at least 3 years.
Work a balanced fertilizer such as 5-10-10 into the soil at the rate of 2 to 4 pounds per 100 square feet.
Raised beds can help avoid the freeze-thaw cycle that rots plants.
In flats sow seeds 1 inch apart. Transplant into 2 1/2 inch pots after the first two true leaves appear. When roots are established, transplant to the garden, spacing the plants 14 to 24 inches apart.
To sow seeds directly in the garden, plant 4 to 5 seeds per foot to a depth of 1/4 inch.
Thin the healthiest direct-seeded plants to stand 14 to 24 inches apart when they are 4 to 5 inches tall.
Side-dress plants once a month during the growing season with a balanced fertilizer.
Mulch to retain moisture in summer heat and to control weeds.
When sprouts reach half the desired size, remove the lowest leaves on the plant to enable the sprouts to attain maximum size.
To induce early maturity, pinch out the growing tip sprouts have formed on 10 or 12 inches of the stem. This directs the plant's energy into making more leaves, less stalk and earlier, larger sprouts.
See our article Summer's Bad Guys by Charlie Nardozzi for controls of common Brussels sprout pests such as aphids, flea beetles, cabbageworms, and cabbage loopers.
The best harvest is after a fall frost.
Harvest sprouts from the bottom of the plant up when they're 1 to 1 1/2 inches in diameter.
Harvest as needed. Plants are tolerant of light frosts.