Sweet Alyssum in Zone 7B — Texas

Sweet Alyssum is a low-growing, spreading plant with a delicate, honey-like scent that makes it a delightful addition to any Texas garden. It's perfect for edging, spilling over containers, or even acting as a living mulch. Plus, it attracts beneficial insects, which is always a win in our gardens.

The Texas heat can be brutal, and our weather unpredictable, but don't let that deter you. With our long 255-day growing season and a little planning, you can enjoy Sweet Alyssum in both your spring and fall gardens. Timing your planting right is key to success!

Starting Sweet Alyssum indoors isn't always necessary, but it gives you a head start, especially for a spring bloom. If you want to get a jump on the season, start your seeds indoors in early to late January, 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 by bottom watering—set the tray in a shallow dish of water and let the soil absorb it from the bottom. This helps prevent damping-off. Provide warmth and plenty of light, and you'll have seedlings ready to go when the early spring warmth arrives. Remember, spring comes early here in Texas, so be ready!

Transplant your Sweet Alyssum seedlings outdoors in late February through early April, once the danger of a hard freeze has passed. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week.

Choose a spot with full sun to partial shade. Space the plants 6-8 inches apart to allow for their spreading growth habit. Keep an eye on the weather forecast – those late freezes can still sneak up on you!

Direct sowing Sweet Alyssum is a simple and effective method, especially for extending your bloom season into the fall. You can direct sow from late February through late September.

Prepare the soil by loosening it and removing any weeds. Sprinkle the tiny seeds evenly over the surface and gently press them into the soil. Keep the soil consistently moist until the seedlings emerge. Soil temperatures need to be consistently warm, especially for fall plantings to take off. Thin the seedlings to 6-8 inches apart once they are large enough to handle.

Sweet Alyssum needs moderate watering, especially in the Texas heat. While it's not very drought-tolerant, it also doesn't like soggy soil. Finding the right balance is crucial.

During the hottest part of the summer, from June through August, you'll likely need to water every other day, or even daily if the rainfall is scarce. In the spring and fall, when temperatures are milder, watering two to three times a week should suffice. Stick your finger about two inches deep into the soil – if it feels dry, it's time to water. Aim for about 1 inch of water per week.

Water at the base of the plants to avoid wetting the foliage, which can encourage fungal diseases, especially with our variable humidity. Signs of underwatering include wilting leaves and dry, crispy edges. Overwatering can lead to yellowing leaves and root rot. A layer of mulch, like shredded hardwood, can help retain moisture in the soil and reduce the need for frequent watering.

Sweet Alyssum is pretty low-maintenance, but a little pruning can keep it looking its best. The main reason to prune is to shear back leggy growth that occurs during the hottest part of the summer.

When the plants start to look sparse and stretched out, usually in midsummer, shear them back by about half. Don't worry, they'll bounce back quickly. New growth and flowers will appear soon after. As the first frost approaches around mid- November, you can leave the plants as they are. They may survive a light frost and continue to provide some color into the early winter.

Sweet Alyssum is more about enjoying the continuous blooms and attracting beneficial insects than a traditional harvest. You can expect the first blooms about 45 days after planting, so if you plant in late February, you should see flowers starting in early April.

The flowers will continue to bloom throughout the spring and fall, providing a constant source of color and fragrance. There's no need to harvest the flowers unless you want to use them in small bouquets, but their stems are very short. Simply snip off the flower clusters as needed. As the first frost approaches in mid- November, the plants will naturally slow down their production.

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

Downy Mildew

• What it looks like: Yellow patches on the tops of leaves, with a fuzzy, gray-purple growth on the undersides. Leaves brown and die from the bottom up.
• What causes it: This is caused by an oomycete pathogen that thrives in cool, humid conditions. Spores spread through the wind.
• How to fix/prevent it: Remove affected leaves immediately. Improve air circulation around the plants. Water at the base, avoiding overhead watering. You can use a copper-based fungicide as a preventative measure.

May Die Back in Extreme Heat

• What it looks like: The plant stops flowering, leaves turn brown and crispy, and overall growth slows or stops.
• What causes it: The intense Texas heat can stress Sweet Alyssum, causing it to go dormant or even die back.
• How to fix/prevent it: Provide afternoon shade during the hottest part of the day. Water deeply and regularly, especially during dry spells. Mulch around the plants to help retain moisture in the soil. Don't worry, with cooler temperatures, they often bounce back.

Flea Beetles

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

Texas Specific Challenges: The hot-to-extreme heat, variable humidity, and unpredictable rainfall in Texas can create challenges for Sweet Alyssum. Be sure to monitor your plants closely, adjust your watering schedule as needed, and provide shade during the hottest part of the day to keep them thriving.

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

Good companions include:

• Broccoli: The beneficial insects attracted by Sweet Alyssum can help control pests that attack broccoli.
• Potato: Sweet Alyssum can help deter potato beetles.
• Lettuce: As a ground cover, Sweet Alyssum can help keep the soil cool and moist for lettuce during the hotter months.

Avoid planting it near anything that requires very dry conditions, as Sweet Alyssum prefers moderate moisture.