Brussels sprout plants looks like they belong in a science fiction or dinosaur movie. The 2- to 3-foot-tall stalks grow studded with what looks like blue-green miniature cabbages. The flavor is milder and nuttier than cabbage. Sprouts are a cool-season cole crop usually planted in late summer and harvested after frost. Other cole crops include cabbage, cauliflower, collards, kale, and kohlrabi.
This vegetable is most easily grown in cold regions. In warm regions, plants grow but temperatures may not get cold enough for sprouts to form.
Select a site with well-drained soil in full sun. If you regularly plant Brussels sprouts or other cole crops, move them to a different garden spot every three or four years.
Start Brussels sprout plants from seeds about four months before your location's average fall frost date. Sow the seeds 1/4 inch deep in a container filled with potting mix. Keep the soil evenly moist but not waterlogged. When seedlings grow large enough to transplant, move them outdoors but keep them in a shaded area for a week or so until they acclimate to brighter light.
Transplant the seedlings into the ground, spacing them 24 inches apart and adding a 10-10-10 fertilizer following package directions. Mulch the plants with 2 to 3 inches of a biodegradable material, such as straw or grass clippings from a lawn that hasn't been chemically treated.
Begin harvesting the sprouts from the bottom of the stalk as they mature and feel solid to the touch. Snap them off by gently pulling down and away from the stalk. The plant's root system is shallow, so take care not to pull it out of the ground.
When ready to harvest, sprouts should be 1 to 1-1/2 inches wide—about the size of a walnut.
When frost hits, rejoice, as the flavor of Brussels sprouts improves.
Cold-climate gardeners may bury the plants up to their tops in straw or hay in late fall, harvesting sprouts throughout the winter. However, if you want the plant to mature before winter, snip off the top of the plant about 21 days before you want to finish the harvest. This pruning tricks the plant into believing it will die so it sets sprouts.
It's believed that Brussels sprouts were first discovered as a sport (natural mutation) from a cabbage plant in the Brussels area of Belgium about 1750. No matter what you call them, Brussels sprouts are high in potassium, vitamins A and C, and vegetable protein.