Growing Brussels Sprouts Successfully: It's All About Timing

How does the ugly duckling of vegetables become a beautiful swan? How did Brussels sprouts, the vegetable about which unflattering jokes and poems were written a century ago, become a favorite of modern cooks?

There was a convergence of events. Early strains of Brussels sprouts really did turn bitter under stressful growing conditions, making them hard to digest. Then, a flurry of breeding work in the 1990s helped to reduce the bitterness in most modern Brussels sprouts varieties, making them much easier to love. Meanwhile, celebrity chef David Chang began serving charred, caramelised Brussels sprouts in his New York restaurant in 2004, and they have increased in popularity ever since. While Americans will never catch up with the British, who eat more than 5 pounds (2 kg) of Brussels sprouts per person per year, US consumption has increased fivefold in the last decade.

When To Sow Brussels Sprouts

So of course you want to grow them in your garden! This is a straightforward matter if you live in a cool maritime climate like Belgium, Great Britain, or the Pacific Northwest. In these and other climates with cool summers and mild winters, Brussels sprouts are grown from spring to fall, like late-maturing cabbage, or even through winter.

Elsewhere, growing Brussels sprouts gets tricky because the objective is to have mature plants in the cool, frosty weather of late autumn. Start too early and heat will cause buds to be loose and floppy; wait too late and they will be little nubbins when temperatures drop to damaging levels. The best plan is to start seeds four months before your first frost date. For most of us, this is sometime in June.

Ready to get started?

Starting Brussels Sprouts Seeds

Seeds sown in summer germinate and grow quickly thanks to warm temperatures and plenty of light. You can start seeds on a bright windowsill and move the seedlings to partial shade outdoors as soon as they sprout. Transplant seedlings to individual containers when they have three true leaves, and feed weekly with a water-soluble plant food. Keep the plants in containers until roots start filling the bottoms of the pots.

Meanwhile, prepare the soil by mixing in a generous amount of organic fertiliser, poultry pellets, composted manure, or other dependable source of nitrogen and other nutrients. Brussels sprouts grow well in heavier soils, so enriched clay with a near neutral pH between 6 and 7 is ideal. Like other cabbage family crops, Brussels sprouts can sometimes benefit from a small boost of boron. Consider drenching the soil with 1 tablespoon of household borax mixed with a gallon of water if you have seen hollow stems when growing Brussels sprouts or broccoli in the past, a subtle sign that they could use a bit of boron.

When setting out seedlings, be sure to firm them in very well. Then cover them with lightweight insect netting to filter bright sun and exclude cabbage white butterflies and other common pests.

Brussels Sprouts Maintenance Schedule

After about a month, give the planting a thorough weeding and side dress with a balanced organic fertiliser. Mulch with grass clippings or straw to keep soil cool and moist, and water as needed to provide one inch (2.5 cm) of rain per week. Protect plants from pests with insect netting.

About six weeks before your first frost date, pull back the mulch and side dress again with an organic fertiliser. This is the last opportunity to feed the plants; fertilising after buds begin to set leads to loose sprouts that split easily. Install stakes to keep the plants upright and limit how much they rock in windy weather.

When the plants grow tall, or about three weeks before your first frost date, clip off the top 6 inches (15 cm) from the plants. This step sends the plants’ new growth efforts to the sprouts, and makes it easier to spot early problems with cabbage aphids and whiteflies.

Start twisting off sprouts as soon as they appear near the base of the plants, removing adjoining leaves as you go. The first sprouts will be small, but their size and flavour will improve as autumn gets underway and you hit the middle of the stem. Harvest sprouts twice a week until temperatures dip below 20°F (-7°C). Well-rooted plants can survive to 10°F (-12°C), but the sprouts are damaged at 14°F (-10°C). When nights get this cold, it’s best to harvest your remaining sprouts and store them in the refrigerator.

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