How to Grow Brussels Sprouts
These bite-sized greens are members of the species Brassica oleracea which includes broccoli, cauliflower, kale, and cabbage. They will flower and produce seeds in their second growing season after experiencing cold weather. Brussels sprouts are considered an advanced crop for seed savers.
Time of Planting
Brussels sprouts require a long growing season. Transplant Brussels sprouts outside just before the last frost.
Plant Brussels sprouts seeds ¼ inch deep in flats 4-6 weeks before the last frost.
Time to Germination
When growing for seed, increase spacing to 18-24 inches apart in rows that are at least 36 inches apart. Staking is recommended.
Common Pests and Diseases
Brussels sprouts are susceptible to a handful of pests including cabbage butterflies, cabbage loopers, cutworms, flea beetles, harlequin bugs, and the diseases leaf spot and black rot. Many of the pests can be controlled by covering plants with row cover or by applying organic pesticides throughout the growing season.
When and How to Harvest
Begin harvesting sprouts when the sprouts are firm and are approximately 1 inch in diameter. Mature sprouts will develop near the bottom of the plant first. Use a sharp knife to harvest individual sprouts as they mature.
There are many ways to prepare Brussels sprouts. The small leafy nodes can be eaten raw, cut thinly with a mandoline or a sharp knife and mixed with a light dressing for a fresh salad. They can be steamed or boiled and then simply dressed with butter, salt and pepper, and served as a side dish.
Fresh Brussels sprouts will keep for several weeks in the refrigerator. If you’d like to stretch your enjoyment of Brussels sprouts into the winter, this vegetable can be blanched and frozen.
How to Save Brussels Sprout Seeds
Recommended Isolation Distance
Separate varieties by 800 feet to ½ mile.
Recommended Population Sizes
To ensure viable seeds, save seeds from at least 5 plants. When maintaining a variety over many generations, save seeds from 20-50 plants. If you’re saving seeds for genetic preservation of a rare variety, save seeds from 80 plants.
To save seeds from Brussels sprouts, first decide how you will vernalize your plants. Vernalization can happen in the field or in storage. Overwinter Brussels sprouts in the field if you will have 10-12 weeks of cool weather (around 50 degrees F) without regular temperatures below 35 degrees F.
When plants cannot be successfully overwintered in the field, they can be vernalized in storage. Before the first frost, dig up the entire plant, roots and all. Replant Brussels sprout plants into containers filled with slightly moist potting mix or sand. Then, find a place to store your plants. The optimum storage conditions for Brussels sprout vernalization ranges from 34-39 degrees F and 80-95% relative humidity. A traditional root cellar is ideal but garages, sheds, and other unheated structures work well in some climates.
In the spring, when the soil can be worked, replant Brussels sprouts in your garden. Space plants at least 36 inches apart. Staking the plants is recommended to support talk seed stalks.
Assessing Seed Maturity
After flowering and producing seed pods, pods will become dry and turn brown as the seeds inside also mature and brown. As with many of the Brassica crops, the window of time for an optimal harvest may be short as mature pods will begin to shatter and bird predation can become a problem.
Gather seeds by cutting entire branches or by harvesting whole plants. Because of this species’ tendency to shatter, the harvested material should be placed on drop cloths or in containers to prevent seed loss.
Cleaning and Processing
Thresh branches of mature fruit by rubbing the pods between your hands or by flailing the brittle pods against any surface that will cause fruits to break open.
Storage and Viability
Store Brussels sprouts seeds in a cool, dark, and dry place in an airtight container to keep out moisture and humidity. Properly stored Brussels sprouts seeds will remain viable for several years.