Lobelia in Zone 8A — Florida

Lobelia is a fantastic addition to any Florida garden, offering a burst of vibrant blue that's especially welcome since our spring season is reversed. The delicate, spreading habit makes it perfect for adding a splash of color to borders, containers, or hanging baskets. The masses of tiny blue flowers add a touch of whimsy to your garden.

While Florida gardening presents unique challenges like extreme humidity and nematodes, you can manage Lobelia successfully. Our 283-day growing season gives you ample time to enjoy these beauties with careful planning.

Starting Lobelia from seed indoors is possible, but because the seeds are tiny and the growth is slow, it's often easier to buy starts. If you're determined to start your own, begin in late December through mid January, about 10 weeks before you plan to transplant. Use seed trays with a fine-grained seed starting mix and provide warmth and bright light – a grow light is almost essential.

Bottom watering is key to prevent damping off; set your seed trays in a shallow container of water and allow the soil to absorb moisture from below. Remember, our spring here in Florida is reversed, so getting a head start indoors is crucial to enjoying Lobelia before the summer heat arrives.

Transplant your Lobelia seedlings outdoors in mid March through early April, after hardening them off for about a week. Gradually expose them to outdoor conditions, increasing the time each day. Space the plants 4-6 inches apart in a location that receives full sun to part shade.

Keep an eye on the weather forecast, as unexpected temperature swings are always possible this time of year. Remember, the tiny seeds and slow growth make buying starts a good option.

Lobelia needs consistent moisture to thrive in Florida's climate. Aim to keep the soil consistently moist, but not waterlogged. The "finger test" is your best friend – stick your finger about 2 inches into the soil, and if it feels dry, it's time to water.

During the cooler months, water deeply about once a week, providing around 1 inch of water. In the hotter, more humid summer, you may need to water more frequently, especially if they are in containers. Water at the base of the plants to avoid wetting the foliage, which can encourage fungal diseases in our humid environment.

Signs of underwatering include wilting and dry, crispy leaves, while overwatering can lead to yellowing leaves and root rot. A layer of mulch around the base of the plants helps retain moisture and suppress weeds, but be sure to leave space around the stems to prevent rot.

Lobelia requires minimal pruning. The most important thing is to shear them back by about half when flowering slows down in midsummer. This encourages fresh growth and a new flush of flowers when the weather cools in the fall.

Avoid cutting back too harshly; just trim the spent flowers and leggy stems. As the first frost approaches in early December, you can either let the plants die back naturally or try to overwinter them in a protected location, although they may not survive.

Lobelia is grown for its beautiful flowers, so there's no real "harvest" in the traditional sense. Expect masses of tiny blue flowers to appear starting in mid May through early July, about 65 days after transplanting. Simply enjoy the blooms in your garden, as they don't need to be harvested for any culinary or medicinal purpose.

Deadheading spent flowers can encourage continued blooming throughout the season. As the first frost approaches in early December, the plants will naturally decline, and you can remove them from the garden.

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

Dies Back in Extreme Heat

• What it looks like: The plant wilts, leaves turn brown and crispy, and overall growth slows or stops.
• What causes it: Florida's intense summer heat, especially when combined with high humidity, can stress Lobelia.
• How to fix/prevent it: Provide afternoon shade, especially during the hottest part of the day. Ensure adequate watering, but avoid overwatering. Mulch around the base of the plant to help retain moisture and keep the soil cool.

Damping Off from Overwatering

• What it looks like: Seedlings suddenly collapse and die, often with a fuzzy white or gray mold visible on the soil surface.
• What causes it: Overwatering creates a favorable environment for fungal pathogens that attack young seedlings.
• How to fix/prevent it: Use a well-draining seed starting mix. Water from the bottom to avoid wetting the foliage. Ensure good air circulation around the seedlings.

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: Use beer traps (shallow dish of beer sunk into soil). Apply iron phosphate bait (pet-safe). Remove hiding spots. Water in the morning so the soil surface dries by evening. Copper tape around beds. Diatomaceous earth around plants.

Florida Specific Challenges Lobelia can be challenging in Florida due to our hot heat, very-high humidity, and wet-summer rainfall. These conditions can stress the plants, making them more susceptible to fungal diseases and heat-related issues. Providing adequate shade, ensuring good air circulation, and careful watering are crucial for success.

Lobelia makes a great companion plant for several vegetables in your Florida garden. Plant it near tomatoes and peppers to attract pollinators, which will increase fruit set. Lobelia also works well with lettuce, providing ground cover that helps retain moisture in the soil and suppress weeds.

Avoid planting Lobelia near plants that prefer very dry conditions, as its need for consistent moisture could create an unfavorable environment for them.