Long Island Improved
Brassicaceae
Brussels Sprouts
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Long Island Improved was the standard American Brussels sprouts variety for over a century, developed in the 1890s. Modern F1 hybrids (Jade Cross, Diablo) offer better uniformity and disease resistance but many gardeners prefer the open-pollinated flavor.
Brussels sprouts are a defining PNW winter crop. Our long cool autumn produces exceptional sprouts. Long Island Improved is the classic variety. Start indoors in March, transplant May, harvest October through February. The flavor transformation after first frost is dramatic — from bitter and cabbagey to sweet and nutty. A Thanksgiving harvest of homegrown Brussels sprouts is peak PNW gardening.
Start indoors in March for May transplanting. Brussels sprouts require a long season (90-100 days from transplant). Space 18-24" apart (1 per sq ft). They are the heaviest feeders of any brassica: work lots of compost into the planting hole and side-dress monthly with high-nitrogen fertilizer. Stake each plant — they grow 2-3 ft tall and become top-heavy. When sprouts begin forming in leaf axils (starting at the bottom), remove yellowing lower leaves. For tighter sprouts, pinch out the growing tip in early September. Harvest sprouts from bottom up when they reach 1-2" diameter, twisting to snap off. Frost dramatically improves flavor.