Sweet Alyssum in Zone 6A — Southeast

Sweet Alyssum is a fantastic addition to any Zone 6A Southeast garden. Its delicate, honey-scented flowers attract beneficial insects, making it a great companion plant for your veggies. Plus, it thrives in our long summer and provides a beautiful, continuous display of blooms.

We definitely have our challenges here in the Southeast, with our hot and humid summers and the potential for fungal diseases. But with careful timing and a little attention, Sweet Alyssum will flourish in our 198-day growing season, adding beauty and functionality to your garden.

Starting Sweet Alyssum indoors isn't essential, but it can give you a head start, especially if you're eager for early blooms. Start your seeds indoors from early to late February, about six weeks before you plan to transplant them outdoors. Use seed trays with a good seed-starting mix, and keep them in a warm spot with plenty of light – a sunny windowsill or under grow lights works well.

Remember to water from the bottom to prevent damping off, a common problem with seedlings. Place your tray in a shallow dish of water and let the soil absorb it. Our springs here in the Southeast can be moderate, so starting indoors gives your plants a chance to get strong before being exposed to cooler temps.

Transplant your Sweet Alyssum seedlings outdoors from late March through early May, once the danger of frost has passed. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the sun and wind, preventing transplant shock.

Space your plants 6-8 inches apart to allow for their spreading growth habit. Keep an eye on the weather forecast here in the Southeast; those late-season cold snaps can still happen, so be ready to cover your transplants if needed.

Direct sowing Sweet Alyssum is a simple and effective method, especially given our long growing season here in the Southeast. You can direct sow from late March through late August. Prepare your soil by loosening it and removing any weeds or debris.

Sweet Alyssum seeds need light to germinate, so simply press them gently into the soil surface. Keep the soil consistently moist until the seedlings emerge, which usually takes about a week. Thin the seedlings to 6-8 inches apart once they're large enough to handle. Direct sowing is a good option for later season blooms.

Sweet Alyssum needs moderate watering, but it's crucial to get it right in our humid Southeast climate. During the spring and fall, when temperatures are milder, aim for about 1 inch of water per week, either from rainfall or irrigation. Use the "finger test" – if the top 2 inches of soil feel dry, it's time to water.

In the heat of summer, especially during dry spells, you might need to water more frequently, but be careful not to overwater. Sweet Alyssum can go dormant in extreme heat, but it will bounce back when temperatures cool. Water at the base of the plants to avoid wetting the foliage, which can encourage fungal diseases in our humid environment.

Overwatering can lead to root rot, while underwatering will cause the plants to wilt and turn yellow. Mulching around your Sweet Alyssum with pine straw or shredded bark will help retain moisture and suppress weeds, which is always a plus in our gardens.

Sweet Alyssum requires minimal pruning, but a little maintenance can keep your plants looking their best throughout our long growing season. When the plants get leggy and stop blooming profusely, usually in midsummer, shear them back by about half. This encourages fresh growth and a new flush of flowers.

Use sharp scissors or pruning shears to make clean cuts. As the first frost approaches in late October, you can leave the plants in place. They might survive a light frost and continue to bloom for a little longer, and you can always collect seeds for next year's garden.

Sweet Alyssum is primarily grown for its beauty and its ability to attract beneficial insects, so there's really no need to "harvest" it in the traditional sense. The plants flower continuously from mid-May through early November. Just enjoy the blooms and the benefits they bring to your garden.

The flowers aren't typically eaten, but they are great for attracting pollinators and predatory insects that help keep pests in check. As the plants near the end of their life cycle in late October, you can let some of the flowers go to seed and collect them for next year.

To collect seeds, allow the seed pods to dry on the plant. Then, gently crush the pods to release the tiny, brown seeds. Store the seeds in a cool, dry place until you're ready to plant them.

Here are some common problems you might encounter with Sweet Alyssum in the Southeast:

Downy Mildew

• What it looks like: Yellow patches on the upper surface of the leaves, with a fuzzy, gray-purple growth on the undersides. The leaves will eventually turn brown and die, starting from the bottom of the plant.
• What causes it: This fungal disease thrives in our cool, humid conditions, especially during the spring and fall. The spores are spread by wind and splashing water.
• How to fix/prevent it: Remove any affected leaves immediately to prevent the spread of the disease. Improve air circulation around the plants by spacing them properly. Water at the base of the plants to avoid wetting the foliage. Consider using a copper-based fungicide as a preventative measure, especially during periods of high humidity.

May Die Back in Extreme Heat

• What it looks like: The plants may stop blooming, wilt, and even die back in the hottest part of the summer.
• What causes it: Our intense summer heat can be stressful for Sweet Alyssum, especially if the plants are not getting enough water.
• How to fix/prevent it: Provide afternoon shade during the hottest part of the day. Ensure the plants are getting adequate water, especially during dry spells. Mulching around the plants will help retain moisture in the soil. Don't worry if they look a bit sad in August; they'll usually bounce back when the temperatures cool down in the fall.

Flea Beetles

• What it looks like: Tiny, round holes in the leaves, giving them a "shot-hole" appearance. You might also see small, dark beetles that jump when disturbed.
• What causes it: These tiny pests are most damaging to young seedlings.
• How to fix/prevent it: Cover seedlings with row covers to protect them during their vulnerable stage. You can also delay planting until the plants are larger and more resistant to damage. Spraying with neem oil can help control flea beetle populations.

Southeast Specific Challenges: Our hot, humid summers and wet-summer rainfall create the perfect environment for fungal diseases like downy mildew. Be vigilant about monitoring your plants and taking preventative measures. Also, be prepared for a potential die-back during the hottest part of the summer. Don't give up on your Sweet Alyssum; it will likely return with cooler temperatures.

Sweet Alyssum makes an excellent companion plant in the Southeast garden. It attracts beneficial insects like hoverflies and lacewings, which prey on aphids and other pests.

Good companions include broccoli, potato, and lettuce. Broccoli benefits from the pest control provided by the beneficial insects attracted by Sweet Alyssum. Potato plants also benefit from the reduced pest pressure. Lettuce appreciates the shade and cooling effect of Sweet Alyssum, especially during our hot summers. There are no specific bad companions to note.