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How to Grow Regatta Midnight Blue Lobelia

Regatta Midnight Blue Lobelia

Lobelia erinus 'Regatta Midnight Blue'

flower

Regatta Midnight Blue is a compact trailing lobelia cultivar prized for its deep violet-blue flowers and dense, mounding growth habit. This tender annual creates vibrant cascades of tiny blooms throughout the growing season, making it ideal for hanging baskets, containers, and edging. It's a prolific bloomer that attracts pollinators while providing consistent color from spring through fall.

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Example Regatta Midnight Blue Lobelia timeline · Pittsburgh, PA (Zone 6b)

  1. Plant Regatta Midnight Blue Lobelia

    Around Apr 17

    Near Pittsburgh's average last spring frost.

  2. Tend & protect

    Late spring–summer

    Watering, feeding, and pest-watch reminders.

  3. First Regatta Midnight Blue Lobelia blooms

    Around Jun 26

    ≈ 70 days after planting

Sample dates for Pittsburgh, PA. Sign up to get exact Regatta Midnight Blue Lobelia dates for your own zip code.

Growing Conditions

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Sun: Full sun to partial shade (4-8 hours of direct sunlight daily; prefers afternoon shade in hot climates)
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Water: Keep soil consistently moist but not waterlogged. Water when the top inch of soil feels dry. In containers, may need daily watering in hot weather. Reduce watering slightly in cooler periods.
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Spacing: 6-8 inches
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Days to maturity: 70-100 days from seed to first flowers
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Planting depth: Surface sow; seeds need light to germinate. Press lightly into soil or leave uncovered. Keep at 65-75°F for germination.

Soil

Type: Well-draining, fertile potting soil or garden soil
pH: 6.0-7.0
Amendments:
Compost or aged manure for fertility Perlite for improved drainage Organic matter to retain moisture

Growing Zones

Find your zone →

Zones 3-10 as an annual; grown as a tender perennial in zones 9-10

3a 3b 4a 4b 5a 5b 6a 6b 7a 7b 8a 8b 9a 9b 10a 10b

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Growth Stages

1

Seed germination

10-14 days

Tiny seeds are just beginning to sprout, with first cotyledons emerging. Seedlings are extremely delicate and threadlike.

Keep soil moist and warm (65-75°F). Provide bright, indirect light. Use a seedling heat mat if available. Handle with extreme care.

2

Seedling

3-4 weeks

Small plants with 2-4 true leaves develop over the initial weeks. Growth is slow and delicate at this stage.

Maintain consistent moisture and bright light. Begin light fertilizing with diluted liquid fertilizer at half strength. Ensure excellent air circulation to prevent damping-off.

3

Vegetative growth

3-4 weeks

Plants develop fuller foliage and trailing stems begin to form. Foliage is dense and bright green with increasingly visible branching.

Pinch or prune tips to encourage bushier growth and more branching. Fertilize every 2 weeks with balanced fertilizer. Acclimate to outdoor conditions if grown indoors.

4

Flowering

8-12 weeks (continuous until frost)

Masses of tiny deep midnight blue flowers appear at stem tips and throughout the canopy. Plants become increasingly covered in blooms.

Continue regular watering and fertilizing. Deadhead spent flowers to encourage continuous blooming. Ensure good air circulation to prevent mildew.

5

Mature flowering

Throughout season until frost (typically June-October in temperate zones)

Plant reaches full size with abundant, uninterrupted flowering. In hanging baskets, trails cascade with dense flower coverage.

Maintain consistent watering and fertilizing schedule. Watch for pests. Deadhead regularly. Cut back if plant becomes leggy to rejuvenate.

Companion Planting

Plan your garden →

Plant with:

Verbena Bacopa Diascia Petunia Calibrachoa Helichrysum Ivy geranium Begonias Impatiens Sweet alyssum

Avoid planting near:

Plants requiring dry soil Drought-tolerant annuals in container plantings

Common Pests

  • Spray with insecticidal soap or neem oil. Use yellow sticky traps. Ensure good air circulation.

  • Mist plants regularly to increase humidity. Apply neem oil or insecticidal soap. Increase air circulation.

  • Rinse off with strong water spray. Apply insecticidal soap or horticultural oil. Introduce beneficial insects.

  • Allow soil to dry slightly between waterings. Use yellow sticky traps. Apply beneficial nematodes if severe.

  • Improve air circulation. Apply sulfur or potassium bicarbonate fungicide. Avoid overhead watering. Remove affected leaves.

Uses

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Hanging basket & container gardening

Household

Regatta Midnight Blue is specifically bred for container growing and is exceptionally popular in hanging baskets, window boxes, and mixed container plantings. Its trailing habit and prolific flowering make it a top choice for creating cascading displays. [source]

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Garden edging & borders

Household

The compact mounding form makes this cultivar excellent for edging flower beds and creating colorful borders. Its dense growth provides a uniform color edge throughout the season. [source]

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Pollinator attraction

Wildlife

Lobelias are attractive to bees and butterflies, making them valuable additions to pollinator gardens. The abundant small flowers provide consistent nectar sources from summer through fall. [source]

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Floral arrangements & decorative displays

Craft

The trailing stems with dense flower coverage can be incorporated into fresh or dried floral arrangements and decorative displays. Individual sprigs add delicate color to mixed bouquets. [source]

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Landscape color & visual interest

Household

The deep midnight blue flowers provide striking color contrast in garden designs, particularly when paired with bright yellows, whites, or silvers. Creates depth and visual interest in layered plantings. [source]

Harvest Tips

Deadhead spent flowers regularly by pinching off faded blooms. This encourages continuous flowering throughout the season. No traditional harvest; the plant is grown for ornamental flowers, which can be enjoyed in containers or garden beds from spring until the first frost.

Fun Facts

  • 🌱 Regatta Midnight Blue is part of the Regatta Series, a major breakthrough in compact lobelia breeding that won horticultural awards for its uniform growth, early flowering, and superior garden performance compared to older varieties.
  • 🌱 Lobelia seeds are among the tiniest of all flowering plant seeds—up to 30,000 seeds can weigh just one gram—requiring careful handling and surface sowing rather than traditional seed planting methods.
  • 🌱 Despite its delicate appearance, Regatta Midnight Blue is surprisingly heat-tolerant for a lobelia and will continue flowering even in hot summers with proper afternoon shade and consistent moisture.

Gardening Terms

New to gardening? Learn about terms used in this guide:

Annual Cultivar Deadhead Full Sun Partial Shade True Leaves
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