How to grow Brussels Sprouts in New Zealand

Where to plant

Grow Brussels sprouts in full sun in firm, fertile, well-drained soil enriched with compost. Loose soil gives loose, open sprouts. Choose a sheltered spot or plan to stake, as the tall plants rock in the wind. As with all brassicas, rotate beds to avoid clubroot.

• Canterbury, Otago and Southland, Central Otago and other cool districts: the best regions, with the long, cool autumns and winters sprouts need. Sow from January to April, the earlier the better.
• Waikato and Bay of Plenty, the central North Island, Wellington, and Nelson and Marlborough: sow from January to April, early in that window, so plants mature in the coolest months.
• Auckland: marginal, as mild winters often give loose sprouts. Sow early and choose a variety such as Jade, which tolerates warmer weather.
• Northland: our calendar marks it as unsuitable, as mild winters give loose, open buds. Grow broccoli, kale or cabbage instead.

Choosing a variety

• Jade: easy, high yielding and tolerant of both hot and cold weather, with deep green sprouts that come away easily.
• Igor: firm, tightly wrapped, uniform sprouts from top to bottom, for picking singly or all at once. Sow from mid summer for a winter harvest.
• Drumtight: mid season and productive, with firm sprouts that hold their colour and flavour.

How to plant

1. Sow seed about 6 mm deep in trays of seed raising mix in mid to late summer.
2. Keep moist; seedlings appear in 5 to 10 days.
3. Transplant when seedlings are about 7 cm tall, 45 to 60 cm apart, planting a little deeper so the lowest leaves are covered, which steadies the plants.
4. Firm the soil around them, water in and mulch lightly with pea straw.
5. Cover with fine insect mesh straight away against white butterfly and diamondback moth.

Watering and feeding

Water regularly so growth never checks, and mulch to hold moisture. Feed with a liquid fertiliser every few weeks while plants are growing.

Pruning and care through the year

• Stake tall plants, especially in windy gardens.
• About 50 days before you want to harvest, pinch out the growing tip at the top of the stem to send the plant's energy into the sprouts.
• Snap off yellowing lower leaves to let air and light reach the sprouts.
• Keep insect mesh on while white butterfly is active.

Harvesting

Start picking from the bottom of the stem when the sprouts are firm and about 2 to 3 cm across, twisting or snapping them off and working up the stem as they mature. A touch of frost improves the flavour, so harvest through autumn and winter.

Do not wash sprouts before storing. They keep up to a week on the stalk in the fridge, or about four days loose in a bag, and blanch and freeze well.

Growing in pots

One plant can be grown in a large pot at least 50 to 60 cm wide, such as a half wine barrel. Plant it a little deeper for stability, stake it and keep it well watered.

Using it

Roast, steam or stir-fry sprouts, shred them raw into salads, or grill them with balsamic vinegar. The leafy top of the plant can be cooked like cabbage.