Grow and Save Brussels Sprout Seeds

How to Grow Brussels Sprouts

These bite-sized greens are members of the species Brassica oleracea which includes broccoli, cauliflower, kale, collards, kohlrabi, and cabbage. They are a biennial crop type and will flower and produce seeds in their second growing season after experiencing cold weather. Gardeners will not be able to save seeds from Brussels sprout plants in your first season. 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.

Planting and Spacing Requirements

Plant Brussels sprouts seeds ¼ inch deep in flats 4-6 weeks before the last frost. When seedlings are 3-4 inches tall, transplant in garden 18-24 inches apart.

Time to Germination

3-10 days

Special Considerations

Brussels sprouts are biennial. When growing for seed, isolate from other flowering Brassica oleracea in their second year. 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 for Food Consumption

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.

Eating

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.

Storing

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

Life Cycle

Biennial

Recommended Isolation Distance

Separate varieties by 800 feet to ½ mile.

Recommended Population Size

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.

Vernalization

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 18–24 inches apart in rows that are at least 36 inches apart. Staking the plants is recommended to support tall 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 because mature pods can be lost to shattering and bird predation.

Harvesting

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.

Learn more about storing seeds.