Lobelia in Zone 8B — Florida

Lobelia is a fantastic addition to any Florida garden, offering vibrant blue blooms that attract pollinators and add a pop of color to your landscape. While not edible, its beauty and ability to thrive in containers or hanging baskets make it a rewarding plant to grow, especially when the intense summer heat limits other flowering options.

Florida gardening is unique, with our reversed seasons and subtropical climate. Lobelia can be successfully grown here with careful timing. Our 303-day growing season gives you a great window to enjoy its beauty before the occasional winter frost arrives.

Starting Lobelia indoors is possible, but because the seeds are tiny and the plants grow slowly, it's generally easier to buy transplants from your local garden center. However, if you're feeling ambitious, you can start seeds indoors from mid-December through early January, about 10 weeks before you plan to transplant them outdoors. Use seed trays with a good seed-starting mix.

Keep the trays consistently moist by bottom watering and provide warmth and bright light – a grow light works wonders. Remember, our spring character is reversed, so you're starting these seeds when many other gardeners are winding down.

Transplant your Lobelia seedlings outdoors from early to late March, after the danger of frost has passed. Before transplanting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the Florida sunshine and breezes.

Space the plants 4-6 inches apart in well-draining soil. Be mindful of unexpected temperature swings that can happen this time of year. If a cold snap is predicted, be ready to cover your young plants. Given the size of the seeds, many gardeners find it easier to buy established starts from local nurseries.

Lobelia needs consistent moisture, especially in our hot and humid Florida climate. Aim to keep the soil consistently moist, but not waterlogged. It does not tolerate drought, and foliage will start to die back quickly.

During the spring and fall, when temperatures are milder, water deeply about 1 inch per week, checking the soil moisture with the "finger test" – stick your finger about 2 inches into the soil. If it feels dry, it's time to water. In the heat of summer, you may need to water more frequently, especially if your plants are in containers. Florida's wet-summer rainfall can help, but supplement as needed.

Water at the base of the plants to avoid wetting the foliage, as our high humidity can lead to fungal diseases. Signs of underwatering include wilting leaves and dry soil. Overwatering can cause root rot and yellowing leaves. A light layer of pine straw mulch can help retain moisture and suppress weeds.

Lobelia requires minimal pruning. The main goal is to keep it tidy and encourage continued blooming.

When flowering slows down in midsummer – which it will do in the Florida heat – shear back the plants by about half. This encourages fresh growth and more blooms when the weather cools down in the fall. Leave any healthy green foliage, focusing on removing spent flowers and leggy stems.

Lobelia is grown for its beautiful blooms, not for food, so there is no real "harvest." Enjoy the masses of tiny blue flowers in your garden!

You can expect the first flush of blooms from early May through late June, about 65 days after transplanting. To encourage continuous blooming, deadhead spent flowers regularly. This prevents the plant from putting energy into seed production and redirects it towards creating more flowers.

As the first frost approaches around mid-December, you can either let the plants die back naturally or try to overwinter them in a protected location. In our Zone 8B climate, they might survive a mild winter with some protection.

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

Dies Back in Extreme Heat

• What it looks like: The plant stops flowering, leaves turn brown and crispy, and overall growth slows or stops entirely.
• What causes it: Our intense summer heat, especially when combined with humidity, can stress Lobelia.
• How to fix/prevent it: Provide afternoon shade, especially during the hottest part of the day. Ensure adequate watering and consider moving container plants to a cooler location. Don't be alarmed, it should rebound when it cools off.

Damping Off from Overwatering

• What it looks like: Seedlings or young plants suddenly wilt and collapse, often with a fuzzy, mold-like growth at the base of the stem.
• What causes it: Overwatering creates a favorable environment for fungal pathogens that attack young plants. This is exacerbated by Florida's high humidity.
• How to fix/prevent it: Use well-draining soil, avoid overwatering, and ensure good air circulation. Water in the morning so the soil surface dries out by evening.

Slugs

• What it looks like: Irregular holes in leaves, especially 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: Use beer traps (shallow dish of beer sunk into soil). Apply iron phosphate bait (pet-safe). Remove hiding spots like mulch close to the plants. Water in the morning so the soil surface dries by evening. You can also try copper tape around beds or diatomaceous earth around plants.

Florida Specific Challenges: Our hot, humid summers and wet-summer rainfall create ideal conditions for fungal diseases and can stress Lobelia, making it more susceptible to problems. Provide good air circulation, avoid overhead watering, and consider using a fungicide if necessary.

Lobelia makes a great companion plant for several vegetables in your Florida garden.

Tomatoes and peppers benefit from Lobelia because it attracts pollinators, which are essential for fruit production. Lettuce enjoys the partial shade provided by Lobelia, especially during the hotter months, helping to prevent bolting.

Avoid planting Lobelia near plants that require very dry conditions, as its need for consistent moisture could be detrimental to those neighbors.