Brussels Sprouts in Zone 3B — Great Plains

Brussels sprouts often get a bad rap, but homegrown, they're a totally different story. The cool nights and intense sunshine we get out here on the Plains actually concentrates their sugars, giving you a sweeter, nuttier flavor than anything you'll find in the store. They're also surprisingly versatile in the kitchen, and there's a certain satisfaction in harvesting those little green jewels after a light frost.

Growing anything in Zone 3B on the Great Plains comes with challenges, from our short 118-day growing season to unexpected temperature swings and the constant threat of hail. But with a little planning and attention to timing, you can absolutely enjoy a successful Brussels sprouts harvest. We'll walk you through the steps to make it happen.

Since we're dealing with a shorter growing season here, starting Brussels sprouts indoors is the way to go. Aim to start your seeds indoors from early to late April. That gives you about 6 weeks to get them going before transplanting.

Use seed trays or small pots filled with a good seed-starting mix. Keep the soil consistently moist (bottom watering works great!) and provide plenty of warmth and light. A heat mat can speed up germination, and once the seedlings emerge, a grow light will prevent them from getting leggy. Remember, spring weather here can be variable.

Transplanting time is generally mid May through early June, after the danger of hard frost has passed. Before you move your seedlings outdoors permanently, you'll need to harden them off. Give them about a week of gradually increasing exposure to the elements.

When transplanting, space your Brussels sprouts plants about 18-24 inches apart. They need room to grow. Keep an eye on the weather forecast – those late spring cold snaps can still happen, so be ready to cover your seedlings if needed.

Brussels sprouts need consistent moisture to develop those tight, delicious sprouts. Drought stress leads to loose, bitter sprouts, which nobody wants. But we also have to avoid overwatering, especially with our heavy prairie soil.

During the hot summer months, you'll likely need to water your Brussels sprouts deeply a couple of times a week, maybe even three if it's really dry. Use the finger test: stick your finger about two inches into the soil. If it feels dry, it's time to water. Aim for about an inch of water each time. Water at the base of the plants to avoid getting the foliage wet, which can encourage disease, even with our low-to-moderate humidity. Wilting leaves in the heat of the day can be a sign of underwatering, but yellowing leaves can indicate overwatering. A good layer of mulch around your plants will help retain moisture and keep the soil cool.

Brussels sprouts plants get tall and can become top-heavy, especially when loaded with sprouts. And with our strong Plains winds, they're prone to toppling over.

Staking is the best way to support them. Use sturdy stakes, like bamboo or metal, and insert them into the ground near the plants at transplant time. As the plants grow, gently tie the stalks to the stakes with soft twine or plant ties. This will help keep them upright and prevent wind damage. Consider location, too. Planting in an area with some natural wind protection is essential.

Pruning Brussels sprouts is pretty straightforward. The main thing is to remove the lower leaves as the sprouts develop upward. This helps improve air circulation and allows the plant to focus its energy on sprout production.

About 3-4 weeks before you want to start harvesting, top the plant by cutting off the growing tip. This forces the plant to put all its energy into maturing the sprouts. Keep in mind that our first frost can arrive around mid- September, so timing is key.

You can usually start harvesting Brussels sprouts from mid August through late September. The sprouts are ready when they're firm, tight, and about 1-2 inches in diameter. Start harvesting from the bottom of the stalk and work your way up.

To harvest, simply twist or snap the sprouts off the stem. The flavor of Brussels sprouts actually improves after a light frost, so don't be afraid to leave them on the plant a little longer if the weather allows. The plant will continue to produce sprouts as you harvest, so keep checking it regularly. Keep an eye on the forecast as we approach our average first frost.

Even with the best care, Brussels sprouts can run into a few problems. Here are some common ones we see here on the Plains:

Aphids

• What it looks like: Clusters of tiny green, black, or white insects 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: A strong blast of water from the hose can knock them off. Encourage natural predators like ladybugs and lacewings. Insecticidal soap works well, and neem oil can be used for heavier infestations. Avoid over-fertilizing with nitrogen, which attracts them.

Cabbage Worms

• What it looks like: Smooth green caterpillars chewing irregular holes in leaves. Dark green droppings. White butterflies fluttering around the plants.
• What causes it: Larvae of those white cabbage butterflies. We can get multiple generations in a season.
• How to fix/prevent it: Bt spray is very effective. Floating row covers can prevent the butterflies from laying eggs in the first place. Handpicking the caterpillars is also an option. Interplanting with aromatic herbs like thyme and sage can help deter them.

Loose Sprouts from Heat

• What it looks like: Instead of tight, compact sprouts, the leaves are loose and open. The sprouts can taste bitter.
• What causes it: High temperatures during sprout development.
• How to fix/prevent it: Choose heat-tolerant varieties. Provide consistent moisture, especially during hot spells. Mulch well to keep the soil cool. Shade cloth can offer some protection during the hottest part of the day.

Clubroot

• What it looks like: Stunted growth, wilting in the afternoon heat, and yellowing leaves. When you dig up the plant, the roots are swollen, distorted, and club-shaped.
• What causes it: A soil-borne pathogen (Plasmodiophora brassicae) that can persist in the soil for 10+ years. It thrives in acidic, wet soil.
• How to fix/prevent it: Raise the 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 them). Start transplants in a sterile mix.

Great Plains Specific Challenges: Our hot summer heat can definitely stress Brussels sprouts, leading to loose sprouts and bitterness. Variable rainfall means you have to be vigilant about watering. And the wind can wreak havoc on tall, unsupported plants. Choosing the right varieties, providing consistent moisture, and offering adequate support are key to overcoming these challenges.

Companion planting can really boost your Brussels sprouts game. Green beans are a great choice because they fix nitrogen in the soil, which Brussels sprouts love. Celery helps deter cabbage white butterflies, and onions can repel aphids. Potatoes are also said to improve the flavor of Brussels sprouts. Dill attracts beneficial insects that prey on pests.

On the other hand, avoid planting tomatoes, strawberries, and peppers near your Brussels sprouts. Tomatoes and peppers are heavy feeders that compete for nutrients. Strawberries are susceptible to verticillium wilt, which can also affect Brussels sprouts.