Lobelia in Zone 7B — Texas

Lobelia's vibrant blue flowers add a pop of color to our Texas gardens, and they're especially welcome in containers and hanging baskets. They're easy to enjoy as garden flowers and don't require any harvesting. The long growing season here in Zone 7B means you can enjoy them through much of the year if you manage the Texas heat right.

We know our Texas weather can be unpredictable, with periods of drought followed by flash floods, and the ever-present threat of extreme heat. But don't worry, Lobelia can thrive here with proper timing and care. Our 255-day growing season gives you a good window to work with.

Starting Lobelia indoors is doable, but be warned, the seeds are tiny and the seedlings grow slowly. If you're up for a challenge, go for it. But honestly, buying starts from a local nursery is a perfectly good option, especially if you are new to the plant.

If you decide to start from seed, sow them early to late January. You'll need seed trays, a good seed-starting mix, and a warm, bright location – a sunny windowsill or under grow lights will work. Gently bottom water your seedlings to keep the soil consistently moist without disturbing the tiny seeds. Keep in mind our early spring warmth here in Texas, and be ready to move them outside when the time is right.

Transplant your Lobelia outdoors from late March through late April, after the last expected frost. 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.

Plant them 4-6 inches apart in well-draining soil. The weather during this time can be variable, so keep an eye on the forecast for any late freezes or sudden heat waves. You may need to protect them with row covers if temperatures dip unexpectedly.

Watering is crucial for Lobelia in our Texas climate. These plants are not drought-tolerant and need consistently moist soil, especially during our hot-to-extreme summers. They will go dormant if they dry out too much.

During the spring and fall, when temperatures are milder, check the soil moisture by sticking your finger about 2 inches deep. If it feels dry, it's time to water. Aim for about 1 inch of water per week, either from rainfall or irrigation. In the heat of summer, you may need to water more frequently, possibly every day, to keep the soil consistently moist. 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, on the other hand, can lead to root rot, indicated by yellowing leaves and a mushy stem. A good layer of mulch, like shredded bark or pine straw, can help retain moisture and regulate soil temperature, which is a lifesaver during the Texas heat.

Lobelia requires minimal pruning, but a little care can keep them blooming longer. When flowering slows down in midsummer, shear back the plants by about half. This encourages fresh growth and a new flush of flowers as the weather cools down in the fall.

Just trim back the spent flower stems and any leggy growth, leaving the healthy foliage intact. As our first frost approaches around mid- November, you can let the plants go. They likely won't survive the winter, but you can always collect seeds for next year if you're feeling ambitious.

Lobelia is grown for its beautiful flowers, so there's no real "harvest" in the traditional sense. You'll start to see masses of tiny blue flowers from late May through mid July, about 65 days after planting.

Simply enjoy the blooms in your garden or containers. Deadheading spent flowers can encourage more blooms, but it's not essential. As the first frost approaches in mid- November, the plants will naturally decline. You can collect seeds from dried flower heads to sow next year, but be aware that they may not come true to the parent plant.

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

Dies Back in Extreme Heat

• What it looks like: The plant wilts, leaves turn brown and crispy, and overall growth slows or stops completely.
• What causes it: The Texas heat is brutal, and Lobelia struggles when temperatures consistently stay above 90°F. The plant can't take up enough water to compensate for the intense evaporation.
• How to fix/prevent it: Provide afternoon shade with shade cloth or by planting in a location that receives morning sun and afternoon shade. Water more frequently during hot spells, and consider using a soil drench to help the roots absorb water. Mulch also helps to keep the roots cooler.

Damping Off

• What it looks like: Seedlings suddenly collapse and die, often with a white, fuzzy growth on the soil surface.
• What causes it: Overwatering and poor air circulation create a breeding ground for fungal diseases that attack young seedlings.
• How to fix/prevent it: Use a sterile seed-starting mix, ensure good air circulation around seedlings, and water from the bottom to avoid wetting the foliage. Avoid overwatering.

Slugs

• What it looks like: Irregular holes in leaves, especially on low-growing plants. Silvery slime trails on leaves and soil. Damage is worse at night and in wet weather.
• What causes it: Slugs are gastropods that feed at night in moist conditions. They hide under mulch, boards, and debris during the day.
• How to fix/prevent it: Set out beer traps (shallow dishes of beer sunk into the soil). Use iron phosphate bait (which is pet-safe). Remove hiding spots like mulch and debris. Water in the morning so the soil surface dries out by evening. Copper tape around beds can deter slugs. Diatomaceous earth around plants can also help.

Texas Specific Challenges: Our hot-to-extreme heat, variable humidity, and unpredictable rainfall can make growing Lobelia challenging. The key is to provide consistent moisture, protect them from the harshest sun, and watch out for fungal diseases. Mulching is your friend!

Lobelia makes a great companion plant for several vegetables in our Texas gardens. Plant them near tomatoes and peppers; their delicate flowers attract pollinators, which can improve fruit set. They also work well with lettuce, providing some shade and helping to keep the soil cool.

Avoid planting Lobelia near plants that prefer very dry conditions, as their need for consistent moisture could create an unfavorable environment for those drier-loving companions.