Brussels Sprouts in Zone 7A — Midwest

Brussels sprouts are a rewarding crop for the Midwest gardener, offering a unique, nutty flavor that's enhanced by our cool fall weather. Nothing beats the taste of fresh, homegrown sprouts roasted with a little olive oil and salt – a true taste of the season. Plus, they're a surprisingly versatile vegetable in the kitchen.

Our Midwest weather can be unpredictable, with late frosts in spring and summer heat spells. But with careful timing and a little attention, you can absolutely grow a fantastic crop of Brussels sprouts during our 193-day growing season.

Starting Brussels sprouts indoors gives you a head start, especially with their long growing season. Aim to start your seeds mid-February through mid-March, about six weeks before you plan to transplant them outdoors. This helps them get established before the summer heat hits.

Use seed trays or small pots filled with a good seed-starting mix. Keep them warm (around 70°F) and provide plenty of light – a grow light works wonders, especially given our moderate-to-late spring. Don't forget to water from the bottom to avoid damping off.

Because Brussels Sprouts take a long time to mature, you will either want to start them early in the spring or plant them for a fall harvest.

Transplant your Brussels sprouts seedlings outdoors early April through early May, after the risk of hard frost has passed. Before planting, be sure to harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the Midwest weather.

Space the plants 18-24 inches apart in fertile soil that drains well. Keep an eye on the forecast – we sometimes get unexpected cold snaps even in late spring.

Brussels sprouts need consistent moisture, especially during those summer heat spells we often get in the Midwest. Aim for about 1-1.5 inches of water per week, either from rainfall or irrigation. Our wet-summer rainfall helps, but don't rely on it entirely.

Stick your finger about 2 inches deep into the soil to check moisture levels. If it feels dry, it's time to water. Water at the base of the plants to avoid wetting the leaves, which can encourage fungal diseases in our moderate-to-humid climate.

Yellowing leaves or stunted growth can signal underwatering, while soggy soil indicates overwatering. A layer of mulch can help retain moisture and regulate soil temperature, which is especially helpful during our hotter stretches.

Brussels sprouts can get quite tall and top-heavy, especially when those sprouts start developing. Staking them is a good idea, especially considering the occasional tornadoes/severe weather we get here in the Midwest.

The best support is a sturdy stake for each plant. Install the stakes when the plants are around 2 feet tall to prevent them from falling over, especially when wind kicks up. Tie the main stalk loosely to the stake with soft twine or plant tape.

Pruning Brussels sprouts is fairly minimal, but it can help improve your harvest. As the sprouts develop up the stem, remove the yellowing or damaged lower leaves. This encourages air circulation and directs energy to the developing sprouts.

About 3-4 weeks before your expected harvest, top the plant by cutting off the top few inches of the main stem. This forces the plant to put all its energy into maturing the sprouts. With our first frost around mid- October, this helps to ensure you'll get a good harvest before the cold sets in.

You can expect your first harvest of Brussels sprouts early July through mid August, about 90 days after transplanting. Look for firm, tight sprouts that are about 1-2 inches in diameter. Start harvesting from the bottom of the plant upwards.

To harvest, simply twist or snap off the sprouts from the stem. Don't pull them, as this can damage the plant. Brussels sprouts have a better flavor after a frost, so don't be afraid to leave them on the plant until after that first cold snap.

Keep harvesting the sprouts as they mature, and the plant will continue to produce. If a hard freeze is coming, you can harvest the entire stalk and store it in a cool, dry place.

Here are some common problems you might encounter growing 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 soft or leafy. They may also taste bitter.
• What causes it: High temperatures during sprout development, especially during those summer heat spells.
• How to fix/prevent it: Provide consistent moisture, mulch around the plants to keep the soil cool, and consider providing shade during the hottest part of the day. Planting for a fall harvest can also help avoid this issue.

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 summers can create ideal conditions for pests and diseases to thrive. The wet-summer rainfall can also lead to soil-borne diseases like clubroot. Consistent monitoring and preventative measures are key to a successful harvest.

Good companions for Brussels sprouts include green beans, celery, onions, potatoes, and dill. Green beans help fix nitrogen in the soil, celery repels cabbage white butterflies, onions deter pests, potatoes don't compete for nutrients, and dill attracts beneficial insects.

Avoid planting Brussels sprouts near tomatoes, strawberries, or peppers. Tomatoes and strawberries can attract pests that also affect Brussels sprouts, and peppers can inhibit their growth.