Lobelia in Zone 5A — Great Plains

Lobelia, with its delicate blooms and trailing habit, adds a vibrant splash of blue to our Great Plains gardens. It's fantastic spilling over the edges of containers or softening the harsh lines of rock gardens. Plus, the sheer volume of dainty flowers provides a much-needed pop of color during our intense summer months.

Our region certainly throws some curveballs, with extreme temperature swings and the constant threat of hail. But by starting Lobelia indoors and transplanting at the right time, you can easily enjoy these beauties throughout our 168-day growing season.

Starting Lobelia indoors is recommended, given our relatively short growing season. Aim to sow seeds late February through mid-March, roughly 10 weeks before you plan to transplant them outside. Use seed trays with a good seed-starting mix, providing warmth and consistent moisture.

Bottom watering is an excellent way to keep the soil evenly moist without disturbing the tiny seeds. Remember, our spring weather can be unpredictable, so having a head start indoors gives these delicate plants the best chance to thrive.

Transplant your Lobelia seedlings outdoors early May through early June, after the risk of frost has passed. Before planting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the wind and temperature fluctuations common in our region.

Space the plants 4-6 inches apart, giving them room to spread. Keep an eye on the forecast, as late spring hail is always a possibility. Consider using row covers if severe weather is predicted.

Consistent moisture is key for Lobelia to flourish in our Great Plains climate. While our humidity is generally low-to-moderate, our summers can be scorchers, so these plants need regular watering. Aim to keep the soil consistently moist, but not waterlogged.

During the hottest part of the summer, you'll likely need to water deeply every other day, or even daily if the soil dries out quickly. Use the finger test: if the top two inches of soil feel dry, it's time to water. Aim for about an inch of water per week, either from rainfall or irrigation. Water at the base of the plants to minimize fungal issues, which can occur even with our lower humidity.

Signs of underwatering include wilting leaves and a lack of blooms. Overwatering can lead to yellowing leaves and root rot. A layer of mulch can help retain moisture and regulate soil temperature, which is especially helpful during our extreme temperature swings.

Lobelia requires minimal pruning, but a little maintenance will keep it looking its best. When flowering slows down in midsummer, shear the plants back by about half. This encourages fresh growth and a new flush of blooms as the weather cools down in the fall.

Simply use sharp scissors or pruning shears to trim the plants back. Don't worry about being too precise; Lobelia is quite forgiving. As the first frost approaches in early October, you can let the plants fade naturally. They are annuals, so they won't survive our winters.

Lobelia is primarily grown for its ornamental value, so there's no need to "harvest" anything in the traditional sense. Expect to see the first masses of tiny blue flowers mid-July through late August, about 65 days after planting. Simply enjoy the beauty they bring to your garden!

To encourage continued production, deadhead spent flowers regularly. This prevents the plant from putting energy into seed production and encourages more blooms. As the end of the season approaches and the first frost looms, simply let the plants fade gracefully.

Here are some common issues you might encounter with Lobelia in the Great Plains:

Dies back in extreme heat

• What it looks like: The plant wilts, leaves turn brown and crispy, and flowering stops.
• What causes it: Intense summer heat and drought stress common in our region.
• How to fix/prevent it: Provide afternoon shade, water deeply and regularly, and mulch to retain moisture. Consider moving container plants to a cooler location during heat waves.

Damping off from overwatering

• What it looks like: Seedlings suddenly collapse and die, often with a fuzzy white or gray mold at the base.
• What causes it: Overly wet soil and poor air circulation, especially during seed starting.
• How to fix/prevent it: Use a well-draining seed-starting mix, avoid overwatering, and provide good air circulation. Bottom watering can help prevent this.

Slugs

• What it looks like: Irregular holes in leaves, especially low-growing plants. Silvery slime trails on leaves and soil. Damage worse at night and in wet weather.
• What causes it: Gastropods that feed at night in moist conditions. Hide under mulch, boards, and debris during the day.
• How to fix/prevent it: Beer traps (shallow dish of beer sunk into soil). Iron phosphate bait (pet-safe). Remove hiding spots. Water in morning so soil surface dries by evening. Copper tape around beds. Diatomaceous earth around plants.

Great Plains Specific Challenges: Our region's combination of hot, dry summers and variable rainfall can be tough on Lobelia. Consistent watering is crucial, and providing some afternoon shade can help prevent heat stress. Mulching is also essential to retain moisture and regulate soil temperature.

Lobelia makes a great companion plant for many vegetables and flowers in our Great Plains gardens.

• Tomato: Lobelia attracts beneficial insects that can help pollinate tomato plants and control pests. Plus, the trailing habit of Lobelia can help shade the soil and retain moisture, which is especially helpful during our hot summers.
• Pepper: Similar to tomatoes, Lobelia attracts beneficial insects that can help pollinate pepper plants and control pests. The splash of color also adds visual appeal to the garden.
• Lettuce: Lobelia provides shade for lettuce, helping to prevent it from bolting (going to seed) in the heat. This extends the lettuce harvest, which is especially valuable in our short growing season.

Avoid planting Lobelia near plants that require very dry soil, as its need for consistent moisture may create an unsuitable environment for those companions.