As a kid I was definitely not a fan of brussels sprouts. Boy, have times changed! Now I grow several varieties every year, waiting impatiently for the harvest season to begin in late autumn. Growing brussels sprouts isn’t difficult but it does require patience as the plants take about four months to go from seed to harvest. If you love this cabbage cousin as much as I do, read on to learn how to grow a bumper crop of crisp, crunchy brussels sprouts.
There are so many reasons to find space for brussels sprouts (Brassica oleracea var gemmifera) in your garden. First, this is a vegetable, with a long ‘days to maturity’, whose harvest begins in late autumn, long after most other crops are finished for the season. And, once they’re ready to pick, they hold their quality for about two months so you can harvest the crop gradually.
Brussels sprout plants also very ornamental, growing two to four feet with large bright green or purple leaves, depending which variety you’re growing. The edible parts are the small, cabbage-like heads that form along the stem at each leaf axil. If you’re growing a green variety, you’ll have green sprouts. If you’re growing a purple variety, you’ll have purple sprouts.
Growing brussels sprouts from seed
Timing is everything when it comes to growing brussels sprouts. In cold climates they’re planted in late spring to early summer and harvested about four months later. I start my seeds indoors in mid to late May, moving the seedlings to the garden after four to six weeks of growth. In warmer climates, brussels sprouts are planted in mid to late summer and harvested in early winter.
You can direct seed, but I find the young plants are susceptible to garden pests like slugs. Instead, I like to start the seeds indoors and then transplant sturdy, healthy brussels sprouts seedlings into my garden. You can use a sunny windowsill but you’ll produce stockier seedlings under grow lights.
Fill seed flats or pots with a high quality seed starting mix and sow seeds a quarter of an inch deep. Cover with a growing dome or a sheet of plastic wrap to hold humidity and encourage good germination. Once the seeds sprout, remove any covers. Keep the soil consistently moist, but not wet, and fertilize with a liquid organic vegetable food every few weeks to promote healthy growth. About a week before you intend to transplant the seedlings into the garden begin to harden them off. This essential step acclimatizes the young plants to outdoor growing conditions. If you’re not sure how to harden off seedlings, check out this article.
Planting brussels sprouts
As the seedlings are hardening off, prep the garden for transplanting. Brussels sprouts are a cool weather vegetable and grow best in full sun and fertile soil. I like to dig in a few inches of compost or aged manure before planting as well as a granular organic fertilizer or kelp meal. Space plants 18 to 24 inches apart and rows three feet apart. If direct seeding, sow a seed every six inches, eventually thinning to 18 to 24 inches apart.
Because members of the cabbage family, like brussels sprouts are susceptible to pests like imported cabbage worms, I cover the plants with a lightweight insect barrier fabric. This prevents the butterflies from laying eggs on the leaves. If you wish to protect your plants, cover immediately after planting. The fabric can be placed directly overtop the plants (leave plenty of slack for growth) or you can float the fabric on hoops.
You can also grow brussels sprouts in containers, but choose large pots or fabric planters that offer plenty of root room for the big plants. Also, add compost to the planting medium to increase organic matter and water retention.
Summer care and maintenance
Brussels sprouts need a long growing season so don’t slack off in summer. There are four main summer tasks to consider when growing brussels sprouts:
- Watering – Consistent water is essential to producing large, productive plants. In dry conditions, water deeply twice a week and use a mulching material like straw, grass clippings, or shredded leaves to retain soil moisture.
- Fertilizing – Because brussels sprouts are in the garden for such a long time, I fertilize twice during the season to encourage healthy growth. The first feed takes place about six weeks after planting and the second six weeks later. I use a liquid organic fish emulsion but any organic vegetable fertilizer will do.
- Staking – Brussels sprouts can grow up to four feet tall, depending on the variety and soil fertility. Some gardeners like to stake their plants in late summer to prevent them from toppling over. Place a bamboo stake beside each plant, tying them to the stake with twine. Toppling over is more of an issue in light soils like sand or loam-based soils. Clay soil helps anchor the plants.
- Topping – As summer comes to a close, it’s time for me to top my plants. I do this around a month before I intend to start harvesting. I typically harvest our sprouts November through January so I top the plants in late September, early October. Topping is just removing the growing tip at the top of each plant and encourages the entire stalk to mature at once. The largest sprouts should be about 1/2 to 1 inch in diameter when you top the plants. Use hand pruners to clip out the top two or three inches of the plant. Quick and easy!
Harvesting brussel sprouts
Fall harvest or winter harvest sprouts. Yet wait until the plants have been hit by at least one frost. Why? It’s simple; frost improves flavour by sweetening the sprouts. By harvest time the individual sprouts should be firm and round. There are two ways to harvest: 1) By picking individual sprouts as the mature from the bottom up or 2) By cutting the entire stalk once all the sprouts have filled out.
- Harvesting individual sprouts – If you’re not harvesting the entire plant, begin by picking the most mature sprouts at the bottom of the stalk. The top sprouts will continue to grow. Breaking off or clipping the leaf just below each sprout makes it easier to harvest. To harvest brussels sprouts, twist and pull. It should break off easily. You can also slice them off with a knife, just watch your fingers.
- Harvesting the entire stalk – Once most of the sprouts on the stalk have reached a uniform size, you can cut the entire stem. Because the stalks can be hard to cut with hand pruners, I use my loppers. They make quick work of cutting down the thick stalks. Whole stalks can be stored in a plastic bag in the refrigerator or in a root cellar for several weeks.
If you decide to leave your plants in the garden for winter harvesting you can cover them with an insulating mulch of evergreen boughs or straw to protect the sprouts from frigid temperatures.
My favorite way to enjoy brussels sprouts is to roast them in the oven which gives them a delicious caramelized flavor. YUM! Here’s a recipe for roasted brussels sprouts.
Pests and diseases of brussels sprouts
Growing brussels sprouts isn’t difficult but there are certain issues you should keep an eye out for. Here are five common pests and diseases of brussels sprouts:
- Imported cabbage worms – This is a common pest of cabbage family vegetables like cabbage, broccoli, kale, and brussels sprouts. The adults are white butterflies with two black dots on each wing. They lay eggs on the leaves and once the green caterpillars hatch, they quickly go to work devouring the foliage. I float insect barrier fabrics or row covers over the plants when I transplant. This prevents the butterflies from laying eggs. You can also handpick eggs or caterpillars throughout the growing season. Find out more about cabbage worms in this detailed article by Jessica. Also watch for cabbage loopers, a similar looking pest of cabbage family vegetables.
- Aphids – Aphids are small, soft-bodied insects that suck the sap from plants. They’re easily knocked off with a hard jet of water from a hose or you can spray with soapy water.
- Slugs – Slugs are a major pest in my garden and I handpick daily in spring to prevent damage. A ring of diatomaceous earth around the plants helps reduce damage. Reapply after rain.
- Cabbage root maggots – Unfortunately by the time you realize you have cabbage root maggots in your brussels sprouts patch, it’s likely too late to save your plants. This pest feeds on the roots of your plants and wilting leaves is often the first sign. Use cardboard collars when you plant to prevent adults, known as cabbage root fly, from laying eggs. Or cover just-planted seedlings with row cover or insect barrier fabric.
- Club root – Club root is a fungal disease that causes large galls to form on the roots of infected plants. The plants grow stunted as they are unable to take up water and nutrients. Prevention is key. Practice crop rotation by never planting brussels sprouts or related crops in the same garden bed two years in a row. Ideally, aim for a four year crop rotation.
Growing Brussels sprouts – varieties to plant
- Hestia (90 days) – An All-America Selections winner, Hestia produces strong, upright plants and an early harvest. The bright green sprouts grow about an inch across.
- Diablo (110 days) – I’ve had excellent luck growing Diablo, a variety that forms two-foot tall plants with stalks well covered in medium-sized sprouts. It’s also disease resistant.
- Jade Cross (95 days) – The award-winning Jade Cross is relatively early to mature with the crunchy sprouts produced on two and a half foot tall stalks.
- Long Island Improved (100 days) – This standard variety grows up to two-feet tall and produces a good crop of one-inch diameter sprouts.
- Falstaff (105 days) – This is a gorgeous red variety for the vegetable garden – or even the flower garden! The plants have dusky purple stalks and stems with deep green leaves. The sprouts are the same reddish-purple, adding bold color to winter meals.
For more information on growing autumn and winter vegetables, check out these articles:
- How to grow kale: tips for planting, preventing pests, and harvesting healthy plants
- 8 vegetables to grow for winter harvesting
- Growing winter vegetables is easier than you think
- Vegetables that taste better after a frost
Are you growing brussels sprouts in your garden?