Brussels Sprouts

Brussels sprouts are the longest-season vegetable most home gardeners will attempt. From transplant to harvest is typically 15 weeks or more, and the plant spends much of that time looking like a tall, somewhat awkward stalk with big leaves and very little to show for your investment. The sprouts themselves — small, tight heads that form in the leaf axils — develop in the final weeks of the season, often after the first frosts have arrived. That frost is not a hazard; it is the point. Cold temperatures convert starches to sugars and give the sprouts their characteristic sweet, nutty flavor.

Start seeds indoors about six weeks before your last frost and transplant around the frost date. The timing matters more here than with other brassicas — transplant too late and the plant won't mature before hard winter freezes arrive; transplant too early into cold waterlogged soil and growth stalls. In zones 7 and colder, a late May or early June transplant gives the plant enough season to develop while still finishing in cool fall weather. In zones 8 and 9, fall planting is typically more successful.

Brussels sprouts are heavy feeders and need fertile, firm soil. Work compost in deeply before planting, and stake the plants or hill up soil around the base as they grow — tall plants on loose soil tip over in wind and rain, which disrupts root function and delays development. Side-dress with a nitrogen-rich fertilizer at six weeks, then switch to a lower-nitrogen formula once you can see sprout development beginning. Excess nitrogen late in the season pushes leafy growth at the expense of tight sprouts.

About a month before expected harvest, remove the growing tip — the top leaves at the very top of the stalk — to redirect the plant's energy into the existing sprouts. This encourages the sprouts to size up and tighten simultaneously rather than continuing to set new ones. Removing lower leaves as they yellow is also helpful; good airflow around the stalk reduces disease pressure. Cabbage worms are a consistent pest, and aphid colonies can build up inside the growing sprouts, invisible until you harvest and cut them open.

Harvest by twisting individual sprouts off the stalk from the bottom up as they reach 1 to 1.5 inches in diameter and feel firm. Don't harvest all at once if you can help it — the plant continues producing for several weeks. In cold climates, the plant can stand through multiple hard frosts and even light snow, and the flavor improves with each cold event. A sprout picked in November after several frosts is genuinely different from one picked in September.