Brussels Sprouts in Zone 6B — Midwest

Brussels sprouts are a true delight in the Midwest garden. Their nutty flavor stands out, especially when kissed by a light frost, making them a perfect addition to your fall meals. Plus, the unique vertical growth of the plant adds an interesting visual element to your garden.

Our Midwest weather can be unpredictable, with temperature swings and the occasional summer heat spell. But by starting your Brussels sprouts indoors and timing your planting carefully within our 183-day growing season, you can enjoy a bountiful harvest.

Starting Brussels sprouts indoors gives them a head start, which is crucial for our region's growing season. You'll want to start your seeds indoors from late February through mid March, about six weeks before you plan to transplant them outside. This helps you avoid our variable spring weather.

Use seed trays with a good seed-starting mix. Keep the trays warm and provide plenty of light, either with a grow light or a sunny windowsill. Remember to water from the bottom to prevent damping off and encourage strong root growth.

Since our springs are moderate-to-late here in the Midwest, this indoor start ensures your plants are ready to thrive as soon as the weather cooperates.

Transplanting your Brussels sprouts seedlings outdoors should happen mid April through early May. Before planting them in the ground, you'll want to harden them off. This means gradually exposing them to outdoor conditions for about a week.

When transplanting, space your Brussels sprouts 18-24 inches apart to give them plenty of room to grow. Keep an eye on the weather forecast, as late frost can still occur in the Midwest during this time, and protect your young plants if necessary.

Brussels sprouts need consistent moisture, especially during those moderate-to-hot summer heat spells we often get in the Midwest. Aim for about 1-1.5 inches of water per week, but adjust based on rainfall. Our wet-summer patterns often provide a good portion of this naturally.

Use the finger test: stick your finger about two inches into the soil. If it feels dry, it's time to water. Water at the base of the plants to avoid getting the leaves wet, as our moderate-to-humid conditions can lead to fungal diseases.

Underwatering can result in loose, bitter sprouts, while overwatering can cause root rot. A good layer of mulch around the base of the plants will help retain moisture and regulate soil temperature, which is especially helpful during those hot spells.

Brussels sprouts can get quite tall and top-heavy, especially in the Midwest where we can get some strong winds. Staking is definitely a good idea to keep them upright.

Bamboo stakes or sturdy wooden stakes work well. Install the stakes when the plants reach about two feet tall, and gently tie the main stem to the stake with soft twine. This will prevent them from toppling over in our sometimes blustery weather.

Pruning Brussels sprouts is pretty straightforward. As the sprouts develop upward along the stalk, remove the yellowing or damaged lower leaves. This helps improve air circulation and directs the plant's energy towards sprout production.

About 3-4 weeks before you plan to start harvesting, top the plant by cutting off the top set of leaves. This encourages the plant to focus its energy on maturing the sprouts. With our first frost typically around mid- October, this timing helps ensure a good harvest before winter sets in.

You can expect your first Brussels sprouts harvest from mid July through late August. The sprouts are ready to pick when they are firm, tight, and about 1-2 inches in diameter. Harvest from the bottom of the stalk upwards, twisting or cutting off the sprouts.

Continue harvesting as the sprouts mature up the stalk. Don't be afraid if a frost hits – in fact, the flavor of Brussels sprouts improves dramatically after a frost, making them even sweeter and more delicious.

As our typical first frost in the Midwest approaches in mid- October, you can harvest the entire stalk if you want to bring them indoors and enjoy them over a longer period.

Here are some common problems you might encounter with Brussels sprouts in the Midwest:

Aphids

• What it looks like: Clusters of tiny soft-bodied insects (green, black, or white) on stems and leaf undersides. Sticky honeydew residue. Curled or distorted new growth.
• What causes it: Rapid-reproducing sap-sucking insects. Populations explode in warm weather. Ant colonies may farm them for honeydew.
• How to fix/prevent it: Strong water spray knocks them off. Encourage ladybugs and lacewings (natural predators). Insecticidal soap for heavy infestations. Neem oil works systemically. Avoid excess nitrogen fertilizer (it attracts them).

Cabbage Worms

• What it looks like: Smooth green caterpillars on brassica leaves. Irregular holes chewed in leaves. Dark green droppings. White butterflies hovering around plants.
• What causes it: Larvae of white cabbage butterflies. Multiple generations per season in warm climates.
• How to fix/prevent it: Bt spray is very effective. Floating row covers prevent egg laying. Handpick caterpillars. Interplant with aromatic herbs (thyme, sage). Encourage parasitic wasps.

Loose Sprouts from Heat

• What it looks like: Sprouts that are not tightly formed and feel loose or leafy. They may also taste bitter.
• What causes it: High temperatures, especially during those summer heat spells we get in the Midwest. The plant struggles to form tight sprouts when it's too hot.
• How to fix/prevent it: Provide consistent watering to reduce stress. Mulch around the plants to keep the soil cool. Consider providing shade during the hottest part of the day. Choose heat-tolerant varieties.

Clubroot

• What it looks like: Stunted growth, wilting in afternoon heat, yellowing leaves. Roots are swollen, distorted, and club-shaped when dug up.
• What causes it: Soil-borne pathogen (Plasmodiophora brassicae) that persists in soil for 10+ years. Favors acidic, wet soil.
• How to fix/prevent it: Raise soil pH to 7.0-7.2 with lime. Improve drainage. Rotate brassicas on a 7-year cycle. Remove and destroy infected plants (don't compost). Start transplants in sterile mix.

Midwest Specific Challenges: The moderate-to-hot heat and moderate-to-humid humidity of our Midwest summers can stress Brussels sprouts, making them more susceptible to pests and diseases. Consistent watering, good air circulation, and careful monitoring are key to success. Our wet-summer rainfall also means good drainage is a MUST to prevent clubroot.

Companion planting can be a great way to help your Brussels sprouts thrive in the Midwest garden. Green beans help fix nitrogen in the soil, which benefits Brussels sprouts, and celery repels cabbage white butterflies, reducing cabbage worm infestations. Onions also deter pests, while potatoes can help break up our often heavy clay soil. Dill attracts beneficial insects that prey on aphids and other pests.

Avoid planting tomatoes, strawberries, and peppers near your Brussels sprouts. Tomatoes and peppers compete for nutrients, and strawberries can attract slugs, which can also damage Brussels sprouts.