When should I sow Brussels sprouts in the UK?

March to April. Earlier (February) sowings tend to bolt; later (May) sowings don't have time to mature decent sprouts before winter. Transplant the seedlings to their final position in June or July when they're pencil-thick.

Why are my Brussels sprouts loose and blown rather than tight?

Loose soil at planting time. Brussels sprouts need a firm, settled bed — they're top-heavy plants that rock in wind, and any movement at the roots produces blown (loose, open-leaved) sprouts. Tread the bed firm before transplanting; firm the soil hard around each plant; stake from autumn onwards.

Do Brussels sprouts really taste better after frost?

Yes, scientifically. Frost triggers the plant to convert starches to sugars as an antifreeze response, sweetening the sprouts dramatically. Pre-frost sprouts (September) tend to taste rough and earthy; post-frost (November onwards) they're sweet. The reason Christmas sprouts always taste better than September ones.

When do I pick Brussels sprouts?

From October when the lower sprouts are walnut-sized and tight; pick through to March the following year. Snap the bottom sprouts off first; work upwards over weeks. A single plant gives 30–50 sprouts spread over 4–5 months of picking — far better value than a single-harvest commercial-style crop.

What's the best variety for the UK?

For uniform commercial-style crops, F1 hybrids (Diablo, Trafalgar, Brigitte) give predictable results. For better flavour and a longer picking window, heritage varieties (Bedford Fillbasket, Long Island Improved) crop over a wider date range with variable sprout size. Most allotment growers split between an F1 (reliability) and a heritage cultivar (flavour).

My sprouts have aphids inside them — what do I do?

Mealy cabbage aphid (Brevicoryne brassicae) gets between the leaves of developing sprouts. Net against butterflies as standard; that doesn't stop aphids. For severe infestations, hose down the plants weekly with a soft soap spray (a teaspoon of washing-up liquid in a litre of water). Encouraging hoverflies and ladybirds (plant flowering dill, coriander, fennel near the brassica bed) is the long-term defence.

Rosenkohl

Brassica oleracea var. gemmifera

Sow Brussels sprout seed from March to April indoors or in a seedbed; transplant 60 cm apart in firm fertile soil from June to July. Brussels sprouts are very hardy (RHS H5–H6) and one of the longest-season UK crops — sown in March you're picking from October through to March the following year. Frost actually sweetens the sprouts; pre-frost picks taste rough. Net against cabbage white butterflies through summer and again against pigeons through winter. Stake firmly at planting — mature plants are top-heavy in autumn gales. Pick from the bottom up as sprouts mature; the leafy top stays on the plant until November to power growth.

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