Brussels sprouts are not for the impatient gardener! These plants take about four months from seed to harvest, and need a little more babying than most. But, harvesting your own sweet sprouts for wintertime holiday dinners is quite a reward, we think. For gardeners in the South, we recommend only planting Brussels sprouts for fall/winter harvest - our summers are just too hot for these cool-weather plants to thrive. It’s also best to start them indoors, where they are protected from the scorching heat and marauding pests.
Start your Brussels sprout seeds in trays indoors about 12 weeks before your first frost date, in late summer. Sow the seeds ¼ to ½ inch deep. Prepare your garden beds by working in a couple inches of high quality compost or well-aged manure. Once your seedlings have reached about 6 inches tall, and temperatures have cooled down, transplant them into the garden 12 to 24 inches apart in rows at least 24 inches apart. If insects are still plentiful, (and they probably will be, especially here in the Southeast) have light row cover or insect netting at the ready, as pests can do a number on young plants in no time. Fertilize with a high-nitrogen fertilizer such as fish emulsion every 3 to 4 weeks after planting, and keep the soil consistently watered but not soggy. Cut off the lower leaves of the plant as they start to yellow, to allow the sprouts more sunlight.
Your Brussels sprouts will start to mature at about 90 days from transplanting. You can harvest them over time by starting from the bottom of each stalk and working your way up. The plants are quite cold-hardy, but you can give them extra protection with row cover if your area will experience snow or very hard freezes.
Brussels sprouts (Brassica oleracea) are an insect-pollinated biennial. They will go to seed in spring after overwintering. In order to save pure seed, they should be isolated from other B. oleracea varieties (this includes most cabbages, collards, kale, and broccoli) that may flower at the same time by a half-mile. Overwintering Brussels sprouts for seed production can be accomplished by covering the plants with row cover and mulching heavily, or digging up some of the plants and bringing them into a root cellar for the winter, then replanting them outdoors as soon as the soil is workable in spring. It’s a good idea to stake Brussels sprouts plants as they start to flower, to prevent the flower stalk from falling over onto the ground, which will invite mold and disease. Harvest the entire seed stalk when most of the pods have started to turn brown. Pods will shatter and drop their seed soon after they ripen, so watch carefully. Finish the drying process by hanging flower stalks indoors over a tarp (to catch seeds from shattered pods). Thresh by crushing the pods in a pillowcase or hitting the stalks against the inside of a clean trash can, then winnow out the chaff by pouring the seeds and chaff from one container to another in front of a fan set on low. Make sure seeds are completely dry before storing them in an airtight container in a dark and cool location.