Brussels Sprouts in Zone 6B — Southeast

Brussels sprouts might not be the first thing you think of growing in the Southeast, but don't let that deter you! When grown right, they offer a delicious, nutty flavor that's fantastic roasted, sautéed, or even shaved raw in salads. Plus, there's real satisfaction in harvesting your own sprouts during the cooler parts of our long summer.

The Southeast's hot, humid summers can present challenges, but with proper timing, Brussels sprouts can thrive. By starting seeds indoors and timing your transplant, you can work within our 208-day growing season and still enjoy a fantastic harvest, especially if you aim for a fall crop.

Starting Brussels sprouts indoors gives them a head start against the summer heat. Begin your seeds mid-February through early March, about six weeks before you plan to transplant. Use seed trays or small pots filled with a good seed-starting mix.

Keep the soil consistently moist (but not soggy) and provide warmth – a heat mat can be very helpful. Place the trays under grow lights to ensure strong, healthy seedlings. Bottom watering is an excellent way to keep the soil evenly moist without encouraging fungal issues. Remember, our moderate spring weather gives you a good window for starting these indoors.

Transplant your Brussels sprouts outdoors early to late April. Before planting, harden off the seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the sunlight and temperature changes.

Space the plants 18-24 inches apart in well-drained soil. Keep an eye on the weather forecast during this time – late frosts can still happen, so be ready to cover the young plants if needed.

Consistent moisture is key for developing tight, flavorful Brussels sprouts, especially with our hot and humid summers. Aim to keep the soil consistently moist, but never waterlogged. Drought stress leads to loose, bitter sprouts, which is the last thing you want.

During the warmer months, check the soil moisture using the finger test – stick your finger about 2 inches deep into the soil. If it feels dry, it's time to water. Typically, Brussels sprouts need about 1-1.5 inches of water per week, either from rainfall or irrigation. Water at the base of the plants to avoid wetting the foliage, which can encourage fungal diseases in our humid climate.

Signs of underwatering include wilting leaves and slow growth. Overwatering, on the other hand, can cause yellowing leaves and root rot. A good layer of mulch, like pine straw or shredded bark, helps retain moisture and suppress weeds, but be sure to keep it away from the plant's stem to prevent rot.

Brussels sprouts grow tall, and those stalks can get top-heavy, especially when loaded with sprouts, and our afternoon thunderstorms can bring strong winds. Staking provides the support they need to stay upright. Bamboo stakes or sturdy garden stakes work well.

Install the stakes when the plants reach about 2 feet tall. Gently tie the main stalk to the stake using soft twine or plant ties. As the plant grows taller, add additional ties as needed.

Pruning Brussels sprouts is fairly minimal, but it can help improve sprout development. As the sprouts start to form along the stem, remove the lower leaves that are yellowing or touching the ground. This improves air circulation and directs the plant's energy towards sprout production.

About 3-4 weeks before you plan to harvest, top the plant by cutting off the top set of leaves. This forces the plant to focus its energy on ripening the existing sprouts. As the first frost approaches in late October, harvest any remaining sprouts that are close to maturity.

You can expect your first harvest of Brussels sprouts from early July through mid-August, about 90 days after planting. The sprouts are ready to harvest when they are firm, tight, and about 1-2 inches in diameter. Start harvesting from the bottom of the stalk upwards, snapping off the sprouts with a downward motion.

After you harvest the lower sprouts, the plant will continue to produce more sprouts higher up the stem. Brussels sprouts actually taste better after a frost, so don't be afraid to leave them in the garden as late as possible. As the first frost approaches in late October, you can harvest the entire stalk or cover the plants with a blanket to extend the harvest a bit longer.

Here are some common problems you might encounter growing Brussels sprouts in the Southeast:

Aphids

• What it looks like: Clusters of tiny green, black, or white insects on stems and leaf undersides. Sticky honeydew residue and curled or distorted new growth.
• What causes it: These sap-sucking insects thrive in warm weather and reproduce rapidly. Ants often protect them.
• How to fix/prevent it: A strong spray of water can knock them off. Encourage beneficial insects like ladybugs. Use insecticidal soap or neem oil for heavy infestations. Avoid excess nitrogen fertilizer.

Cabbage Worms

• What it looks like: Smooth green caterpillars chewing holes in leaves, leaving dark green droppings. White butterflies fluttering around.
• What causes it: Larvae of white cabbage butterflies. Multiple generations occur throughout the warm season.
• How to fix/prevent it: Bt spray is very effective. Use floating row covers to prevent butterflies from laying eggs. Handpick caterpillars and interplant with aromatic herbs.

Loose Sprouts from Heat

• What it looks like: Sprouts that are not tightly formed, but rather loose and leafy. They may also taste bitter.
• What causes it: High temperatures during sprout development.
• How to fix/prevent it: Choose heat-tolerant varieties. Provide afternoon shade during the hottest part of the summer. Ensure consistent watering to prevent drought stress. Mulch around the plants to keep the soil cool.

Clubroot

• What it looks like: Stunted growth, wilting, yellowing leaves. Swollen, distorted roots.
• What causes it: A soil-borne pathogen that persists for years. Favors acidic, wet soil.
• How to fix/prevent it: Raise soil pH with lime. Improve drainage. Rotate brassicas on a 7-year cycle. Remove and destroy infected plants. Start transplants in sterile mix.

Southeast Specific Challenges: The hot, humid climate of the Southeast can exacerbate many of these problems. High humidity encourages fungal diseases, so good air circulation and avoiding overhead watering are essential. Japanese beetles can also be a nuisance, so be vigilant and use appropriate control measures if needed.

Companion planting can help your Brussels sprouts thrive! Green beans fix nitrogen in the soil, benefiting Brussels sprouts. Celery deters cabbage white butterflies, reducing cabbage worm infestations. Onions and dill repel aphids. Potatoes are simply neutral and don't compete for resources.

Avoid planting Brussels sprouts near tomatoes, strawberries, or peppers. Tomatoes and peppers are heavy feeders and can compete for nutrients. Strawberries may attract pests that also affect Brussels sprouts.