Sweet Alyssum in Zone 7A — Texas

Sweet Alyssum is a winner in Texas gardens for its delicate, honey-scented flowers that attract beneficial insects. It makes a beautiful ground cover and can even spill over the edges of containers. Plus, in our climate, you can enjoy its blooms for a good long time.

Our unpredictable weather, including the brutal Texas heat, can be a challenge. But with a 245-day growing season, timing your planting right will help you enjoy sweet alyssum in your garden.

Starting Sweet Alyssum indoors isn't essential, but it can give you a jump start, especially for an early spring bloom. If you want to go this route, sow seeds indoors from mid January through early February, about six weeks before you plan to transplant.

Use seed trays with a good seed-starting mix, keep them warm, and provide plenty of light – a grow light works great. Bottom watering helps prevent damping-off, which can be a problem with seedlings. Get those little roots drinking from the bottom up! Since our springs come early, this method lets you get flowers going before the heat hits.

Transplanting Sweet Alyssum seedlings outdoors is best done in early March through mid April. Before you put them in the ground, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the Texas sun and wind.

Space your plants 6-8 inches apart to allow for their spreading growth habit. Keep an eye on the weather forecast; a late freeze is always possible, even though it's rare.

Direct sowing Sweet Alyssum is a straightforward option, especially with our long growing season. You can direct sow from early March through mid September.

Prepare the soil by loosening it and removing any weeds. Sweet Alyssum seeds are tiny, so just lightly press them into the soil. Keep the soil consistently moist until germination. This method is perfect for filling in gaps in your garden or creating a carpet of flowers.

Sweet Alyssum needs moderate watering to thrive in our Texas gardens. During the hottest part of the summer, it might even go dormant, but don't worry, it usually bounces back when temperatures cool down.

A good rule of thumb is to water deeply once or twice a week, providing about an inch of water each time. Use the "finger test" – if the top two inches of soil feel dry, it's time to water. Water at the base of the plants to avoid wetting the foliage, especially with our variable humidity. Overhead watering can encourage fungal diseases.

Signs of underwatering include wilting and dry, crispy leaves. Overwatering can lead to yellowing leaves and root rot. A layer of mulch can help retain moisture and regulate soil temperature.

Sweet Alyssum requires minimal pruning. The main thing you'll want to do is shear back the plants by about half when they start to get leggy in midsummer. This encourages fresh growth and more blooms.

Don't be afraid to give them a good trim – they're pretty resilient. As the first frost approaches in mid- November, you can let the plants go to seed or pull them up, depending on whether you want them to self-sow next year.

You won't be "harvesting" Sweet Alyssum in the traditional sense. It flowers continuously from mid April through late November, providing a beautiful display and attracting beneficial insects.

The beauty of Sweet Alyssum lies in its continuous blooms and its role as a living mulch. Just enjoy the show! As the first frost approaches in mid- November, you can decide whether to let the plants go to seed or remove them.

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

Downy Mildew

• What it looks like: Yellow patches on the tops of leaves, with fuzzy gray-purple growth on the undersides. Leaves will brown and die, starting from the bottom of the plant.
• What causes it: This is caused by an oomycete pathogen that thrives in cool, humid conditions. Spores are spread by wind.
• How to fix/prevent it: Remove any affected leaves immediately. Improve air circulation around your plants. Water at the base, avoiding overhead watering. Copper-based fungicides can be used for prevention.

Heat Dieback

• What it looks like: Plants may wilt, turn brown, and appear to die back during the hottest parts of the summer.
• What causes it: The extreme Texas heat can be too much for Sweet Alyssum, causing it to go dormant or even die back.
• How to fix/prevent it: Provide afternoon shade during the hottest months. Water deeply and regularly. Mulch around the plants to help retain moisture. Don't give up on them – they often bounce back when the weather cools down.

Flea Beetles

• What it looks like: Tiny, round holes (shot-hole pattern) in the leaves. You might see small, dark beetles that jump when disturbed.
• What causes it: These are caused by small jumping beetles that feed on the leaves, especially of young seedlings.
• How to fix/prevent it: Use row covers to protect seedlings. Delay planting until plants are larger and more resilient. You can also try spraying with neem oil or interplanting with basil or catnip.

Texas Specific Challenges: The hot-to-extreme heat, variable humidity, and unpredictable rainfall can all stress Sweet Alyssum. Consistent watering and some afternoon shade during the hottest months will help them thrive.

Sweet Alyssum makes a great companion plant in the Texas garden. It attracts beneficial insects that can help protect your other plants.

Good companions include broccoli (the alyssum attracts beneficial insects that prey on broccoli pests), potatoes (the ground cover helps retain moisture and suppress weeds), and lettuce (the alyssum provides some shade and helps keep the soil cool). Avoid planting it near anything that prefers very dry conditions, as Sweet Alyssum needs moderate moisture.