Sweet Alyssum in Zone 9B — Texas

Sweet Alyssum is a winner in Texas gardens. It's not just pretty; it attracts beneficial insects to your veggie patch, acts as a living mulch, and handles our variable conditions better than you might think. Plus, it flowers for a long time, giving you a continuous show of color.

While Texas weather can be a beast, with extreme heat and unpredictable freezes, Sweet Alyssum's relatively short maturity time and frost tolerance mean you can squeeze in several plantings during our long, 308-day growing season. Timing is key, and you've got options.

Starting Sweet Alyssum indoors isn't always necessary in our climate, but it can give you a head start, especially for an early spring bloom. If you want to get a jump on the season, aim to start your seeds indoors from early to late December, about six weeks before you plan to transplant them.

Use seed trays with a good seed-starting mix. Keep them consistently moist by bottom watering to avoid disturbing the tiny seeds. You'll need a warm spot and some supplemental light, like a grow light, to get them going strong before the early warmth of spring hits.

Transplanting Sweet Alyssum outdoors can happen from late January through early March. Before you move them outside, harden them off. Give them about a week of gradual exposure to outdoor conditions. Start with an hour or two in a sheltered spot and slowly increase the time each day.

Plant them 6-8 inches apart in well-draining soil. Keep an eye on the weather; those unpredictable freezes can still happen, so be ready to cover them if a cold snap is forecast.

Direct sowing is a perfectly viable option for Sweet Alyssum in Texas. The window for direct sowing is generous, from late January through mid October. This gives you a lot of flexibility to stagger plantings for continuous blooms.

Prepare your soil by loosening it and removing any rocks or debris. Scatter the seeds lightly over the surface and gently press them into the soil. Keep the soil consistently moist until the seedlings emerge. Thin them to 6-8 inches apart once they're established.

Watering Sweet Alyssum in Texas requires a bit of finesse. They need moderate moisture, but they definitely don't like soggy feet. Our unpredictable rainfall can make this tricky, so pay attention to the weather.

In the spring and fall, when temperatures are milder, water deeply about once a week, providing about an inch of water. Use the finger test: stick your finger in the soil about two inches deep. If it's dry, it's time to water. During the brutal Texas heat of summer, they might go dormant, so reduce watering slightly but don't let them dry out completely.

Water at the base of the plants to avoid wetting the foliage. This helps prevent fungal diseases, especially with our variable humidity. Yellowing leaves can indicate overwatering, while wilting leaves signal underwatering. A layer of mulch can help retain moisture and regulate soil temperature, which is especially helpful during the summer months.

Sweet Alyssum doesn't require a lot of pruning, but a little maintenance can keep them looking their best. The main thing is to shear them back by about half when they start to look leggy, usually around midsummer when the Texas heat is at its peak.

Don't be afraid to cut them back; they'll bounce back quickly with fresh growth and more flowers. As the first frost approaches in early December, you can let them be. They might survive the winter, or they might not, but either way, you'll have enjoyed their blooms for most of the year.

You don't really "harvest" Sweet Alyssum in the traditional sense. They flower continuously, and you don't need to deadhead them to encourage more blooms. Instead, think of them as a living mulch and beneficial insect attractant.

Expect the first blooms about 45 days after planting, whether you started them indoors or direct sowed. Keep an eye out starting in early March through mid December. The flowers will just keep coming until the weather gets too cold. As the first frost approaches in early December, you can simply let them be. The beauty of Sweet Alyssum is in its continuous, effortless display.

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. The leaves will eventually 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. The spores are spread by wind.
• How to fix/prevent it: Remove any affected leaves immediately. Improve air circulation around your plants by spacing them properly. Water at the base of the plants, avoiding overhead watering. You can also use a copper-based fungicide as a preventative measure.

May Die Back in Extreme Heat

• What it looks like: The plants will wilt and stop flowering. In severe cases, they may even die back completely.
• What causes it: The brutal Texas heat can be too much for Sweet Alyssum, especially if they aren't getting enough water.
• How to fix/prevent it: Provide afternoon shade during the hottest part of the day. Water deeply and regularly, especially during dry spells. Mulching can also help to keep the soil cool and moist.

Flea Beetles

• What it looks like: Tiny round holes (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 of various plants, including Sweet Alyssum. They are most damaging to young seedlings.
• How to fix/prevent it: Use row covers to protect seedlings during their vulnerable stage. You can also delay planting until the plants are larger and more resilient. Kaolin clay coatings and neem oil sprays can also help to deter flea beetles.

Texas Specific Challenges: The hot-to-extreme heat, variable humidity, and unpredictable rainfall in Texas can all impact Sweet Alyssum. Be prepared to adjust your watering schedule based on the weather conditions. Also, watch out for fungal diseases, which can be more prevalent during periods of high humidity.

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

Good companions include broccoli, potato, and lettuce. Broccoli benefits from the attracted pollinators, and the potato and lettuce can benefit from the pest control. Avoid planting it near any plants that are susceptible to the same diseases, as this can increase the risk of spreading the infection.