Brussels sprouts are cool-season brassicas that taste even better after they have been kissed by frost. Nothing complements a main course in fall quite like fresh Brussels sprouts that came straight to the kitchen from the garden. They have a delicious, slightly crunchy, nutty flavor and can be served roasted, sautéed, steamed and even raw. If you want to grow Brussels sprouts in your garden, here’s what you need to know.
You can also download my How Do I Grow Brussels Sprouts? one-sheet and keep the free resource handy for your reference.
Brussels sprouts are cruciferous vegetables that, believe it or not, are the exact same species as cabbage, broccoli, kale, collard greens and kohlrabi. With their thick stems that grow 2-3 feet tall and their large buds, Brussels sprouts are one of the most interesting looking plants in an edible garden and really stand out in winter after less-hardy plants have faded. They thrive in the Pacific Northwest but will grow just about anywhere that offers cool weather.
Where, When and How to Plant Brussels Sprouts
Brussels sprouts take a long time to mature — anywhere from 85 to 145 days, depending on the variety — and they grow best when temperatures stay below 70° degrees. In the North, to ensure plants have adequate time to produce a few harvests, it’s usually best to start seeds indoors or in a cold frame a month to six weeks before your zone’s last frost date. In frost-free regions, Brussels sprouts may be sown from fall to spring.
Be conscious of the length of your growing season and the specific days to maturity of the varieties you are growing. For spring- or summer-sown crops, the goal is to time it so the plants will mature as the weather gets colder. If it’s hot at that time, plants will become bitter and flimsy.
Brussels sprouts seeds are sown just a quarter-inch deep and will germinate in five to eight days. However, whether starting indoors or direct sowing, the seeds will require a soil temperature of between 60° and 85° in order to germinate.
Seedlings that were started indoors can be planted outdoors after the last possible hard frost or as soon as the soil can be worked. It can also be helpful to put a stake in the ground at this time to later attach the plant to as it grows taller and becomes more susceptible to wind damage.
Seeds or seedlings should be spaced out in the garden about 18 inches apart. Brussels sprouts have shallow roots that require fertile soil, so amend the soil with compost before planting. Like the other brassicas, they also require full sun — at least six hours of direct sunlight — and well-draining soil.
The soil should be neutral to slightly alkaline, between 6.6 and 7.8 pH. A soil test will tell you if the soil is where it needs to be.
Brussels sprouts grow best when the soil temperature stays below 70°. In the warmer months, apply organic mulch such as shredded leaves, arborist’s wood chips or straw to keep the soil from overheating.
Brussels Sprouts Varieties
When choosing Brussels sprouts to grow in your garden, look primarily at the days to maturity, though there are other considerations as well. Most Brussels sprouts are green, but purple varieties are available that can add some striking color to the garden. Here are a few varieties to consider.
Nautic is a hybrid variety with resistance to black rot and high resistance to fusarium. The 1-inch tightly wrapped sprouts are spaced further apart than many varieties’ sprouts, allowing plants to dry out quickly to avoid the spread of disease. Plants take 120 days to mature.
Gladius is intended for an early-to-mid-fall harvest. It is a hybrid, and plants mature in 98 days. The firm blue-green sprouts are consistent in size — a little larger than an inch — and have a long shelf life. The plants grow more than 30 inches tall. A similar variety is Hestia.
Diablo is a hybrid for late-fall or early-winter harvest that grows more than 2 feet tall and matures in 110 days. It is known as a good producer with uniform, medium-size sprouts.
Bubbles is a blue-green hybrid that grows 3-4 feet tall and matures in 90 days. Seeds should be winter sown outdoors, or cold stratified in a refrigerator before starting indoors.
Catskill is an heirloom Brussels sprouts variety that grows just 20-24 inches tall and matures in 85 to 110 days with 2-inch sprouts on sturdy stalks.
Long Island Improved dates back to the turn of the 20th century. It grows 2 feet tall with 1-inch sprouts. It matures in just 90 days, but the seeds take longer to germinate than many other varieties: 10-21 days.
Redarling Hybrid has red-purple sprouts that grow to be 1½ inches in diameter and are sweeter than green varieties. The plants grow 30 to 40 inches tall and take 140 to 145 days to mature.
Watering Brussels Sprouts
Brussels sprouts require 1-2 inches of water a week, so if rainfall comes up short, make up the difference with supplemental watering. If you have a drip irrigation system, it will serve shallow-rooted Brussels sprouts well.
Putting down 1-2 inches of organic mulch will help retain water while also moderating the soil temperature.
Fertilizing Brussels Sprouts
Organic fertilizer high in nitrogen, such as blood meal, cottonseed meal or manure, will help in plants’ overall development and production. A pH level that’s very close to neutral is especially important for Brussels sprouts so that the plants take up nutrients efficiently.
For a fall harvest, fertilize by side-dressing every three to four weeks through the end of summer. Never apply more than the fertilizer bag recommends. It is important to not go overboard with nitrogen. Otherwise, plants will have many leaves but paltry sprouts.
When the plants are reaching maturity and starting to produce, it’s time to stop fertilizing, so the plants concentrate on sprout growth rather than leaf growth.
Brussels Sprouts Pests & Diseases
When Brussels sprouts receive even moisture and experience minimal root disturbance, they will perform much better and be less susceptible to pests and disease. Still, there are pests and pathogens to look out for.
Because Brussels sprouts are the same species as cabbage, they attract the same pests: cabbage loopers, cabbage root maggot, cabbage worms (the larvae of either cabbage white butterflies or diamondback moths), slugs, cabbage aphids and flea beetles.
Small moths and butterflies fluttering above your Brussels sprouts may be scouting out a place to lay their eggs, which will become the worms that eat the leaves.
An easy, chemical-free way to stop pests on Brussels sprouts is to cover plants with a lightweight, translucent floating row cover from the day you put transplants in the garden. You don’t have to keep row cover on the whole season (you can since Brussels sprouts are not dependent on pollinators to mature) but leave it on at least until the plant is well developed and more resilient.
Insecticidal soap is a good contact pest control for the aphids, and Bt is a biological control that’s safe for humans and pets, yet effective against cabbage worms. And as the weather cools off and plants mature, pests should become almost non-existent.
To avoid disease on Brussels sprouts, refrain from overhead watering because wet foliage invites pathogens to take hold. Water at the base of plants instead.
Leaf spot is the most common disease. Fungicidal controls, such as neem oil, help, and I always advise removing any diseased leaves whenever they are found.
If disease becomes an issue, refrain from planting brassicas in that spot for at least two seasons. Giving the area a break from brassicas will reduce the brassica pathogens in the soil.
Harvesting Brussels Sprouts
After a few frosts, Brussels sprouts will be at peak flavor. However, you can pick sprouts whenever they have firmed. It’s also OK to pick sprouts before they have reached that variety’s maximum size. Be sure to harvest from the bottom up.
The leaf below each sprout may be broken off. Then cut off each sprout where the bud meets the stalk.
Some varieties may be topped off about four weeks before the first frost to encourage budding. This can make for more production in a shorter window of time.
If plants are free from disease, leave them in the garden even after all the sprouts have been picked. A plant may surprise you by continuing to produce long after you thought it was done. Even after hard frosts, a plant can remain viable. The season can be extended for quite some time by using a frost blanket when nights dip to 25°.
What are your secrets to successfully growing Brussels sprouts? Let us know in the comments below.
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Links & Resources
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joegardener Online Gardening Academy™: Three popular courses on gardening fundamentals; managing pests, diseases & weeds; and seed starting!
joegardener Online Gardening Academy Master Seed Starting: Everything you need to know to start your own plants from seed — indoors and out.
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