Grow a Vibrant Blue Carpet with Lobelia Seeds

Lobelia seeds produce a beloved garden flower that has been cherished for centuries. With striking blue blooms and a creeping growth habit lobelias make excellent groundcovers and edging plants. One of the most popular varieties is Lobelia erinus commonly called edging lobelia or blue carpet lobelia. These bright blue annuals/short-lived perennials are perfect for carpeting beds, borders, hanging baskets, and window boxes with waves of electric color.

An Overview of Blue Carpet Lobelia

Blue carpet lobelia (Lobelia erinus) is native to South Africa and thrives in warm climates, where it grows as a perennial. However, most gardeners grow it as a fast and prolific annual flower This trailing lobelia produces mounds of foliage just 4-6 inches tall, making it ideal for edging the front of beds and borders The small green leaves are heavily flushed with burgundy-bronze.

Starting in late spring, the foliage becomes covered with hundreds of petite flowers in vivid shades of blue, violet-blue, or white. Each 0.5 inch bloom has a white center and dark veins radiating outward. Blooming continues nonstop throughout the summer without deadheading. And since the tiny blooms are sterile, blue carpet lobelia saves gardeners the hassle of reseeding.

Thanks to its carpet-like growth and profuse flowers, this lobelia excels in mass plantings, as well as cascading out of containers. It can handle full sun in cooler climates but appreciates some afternoon shade in hotter zones. Blue carpet lobelia thrives in moist, organic-rich soil with excellent drainage. But it’s also quite drought tolerant once established.

When and How to Plant Lobelia Seeds

One of the easiest ways to grow blue carpet lobelia is by sowing the tiny seeds directly in the garden after the last frost. However, starting the seeds indoors will produce earlier blooms.

Indoor sowing: For best results, sow lobelia seeds indoors 10-12 weeks before your area’s last expected frost date. Surface sow the seeds and press them gently into a good quality seed starting mix. Keep the soil moist but not soaked. Germination takes 14-21 days at temperatures around 70°F. Once the seedlings have two sets of true leaves, transplant them into cell packs or small containers. Harden off the young plants for 7-10 days before transplanting them outside after all danger of frost has passed. Space the plants 8-12 inches apart in beds, borders, and containers.

Direct sowing: After the danger of frost has passed and the soil has warmed up, sow lobelia seeds directly into the garden. Prepare a planting bed in full sun to partial shade with rich, moist, well-draining soil. Scatter the seeds on the soil surface and lightly press them in. Keep the area evenly moist until the seeds germinate in 14-21 days. Once the seedlings are large enough to handle, thin them 8-12 inches apart.

Growing and Caring for Blue Carpet Lobelia

Here are some tips for successfully growing blue carpet lobelia in your garden:

• Site: Choose a spot with full sun to partial shade and fertile, moist soil. Areas with afternoon shade are ideal.

• Water: Keep the soil consistently moist but not waterlogged. Established plants have some drought tolerance.

• Fertilizer: Apply a balanced liquid fertilizer every 2-3 weeks during the growing season.

• Temperature: Blue carpet lobelia thrives in warm weather. Optimal temperatures are 60-75°F. It can survive light frosts.

• Pruning: Pinch back leggy plants to encourage fullness. Deadhead spent blooms to prolong flowering, though it’s not necessary.

• Pests & Disease: Aphids, snails, slugs, powdery mildew. Avoid wetting the foliage at night.

• Winter Care: In zones 10-11, blue carpet lobelia may survive winter as a perennial. Elsewhere, treat it as an annual and remove the plants after frost.

Uses in the Landscape

Thanks to its carpeting habit and nonstop color, blue carpet lobelia has many uses:

• Edging along beds, borders, and walkways

• Cascading from window boxes and hanging baskets

• Mass plantings or filler in rock gardens

• Mixed containers paired with taller plants

• Groundcover under roses, shrubs, and ornamental trees

• Planted between stepping stones or pavers

• Accent in butterfly and pollinator gardens

Blue Carpet Varieties

There are several variants of Lobelia erinus to choose from:

• Riviera Blue has rich violet-blue blooms on bronze foliage.

• Riviera Marine Blue features light sky blue flowers.

• Riviera Midnight Blue is the darkest blue variety.

• Crystal Palace has deep blue blooms and smaller foliage.

• White Lady produces a carpet of clean white flowers.

No matter which you choose, blue carpet lobelia is sure to create stunning displays with minimal care required. A packet of seeds is all you need to add showy color to beds, borders, baskets, and more.