Brussels sprouts are a cool-season crop that belongs to the cabbage family. Brussels sprouts seeds germinate very slowly and unevenly in the garden. Many gardeners elect to grow the vegetable from transplants purchased at the garden center.
Brussels sprouts should be planted where they will receive at least 8 to 10 hours of full sun. Use a garden fork to work some 10-10-10 fertilizer into the soil at least 12" deep. Mark the placement of the holes, which should be spaced 2' apart in all directions.
Approximately 90 days before the first fall frost date, dig holes to the same depth the seedlings are growing in the plant container. Carefully move plants from their containers to the holes, trying not to disturb the roots. Gently pack soil around the seedlings and water well.
Place a generous layer of straw, compost or leaves around the plants to cool the soil, retain moisture and keep down weeds. Make sure the plants receive 1" of water per week. Side dress with a balanced fertilizer once a month throughout the growing season.
The sprouts mature from the bottom of the plant up, starting in approximately 80 to 90 days. Sprouts should be picked from the stalk while they are still tight, firm and no more than 1 1/2" in diameter. To force the plant to stop producing new sprouts and focus on maturing existing ones, pinch out the growing point at the top. Brussels sprouts picked after a light frost taste sweeter than those picked before.