How to Grow Lobelia
Lobelia erinus
When to Start
Sow indoors 9 weeks before last frost, or direct sow outdoors after frost risk has passed and soil reaches 10°C.
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Growth Stages
Approximate days from start
Care Essentials
- Balanced liquid feed fortnightly. Keep consistently moist.
- Classic edging and container plant. Trailing types are excellent for hanging baskets.
Companion Planting
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Growing Conditions
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- Sow indoors
- —
- Transplant out
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- First harvest
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Spacing & Planting
| Plant spacing | 15 cm |
| Row spacing | 20 cm |
| Sow depth | 0 cm |
| Mature height | 20 cm |
| Mature spread | 20 cm |
For bedding varieties used for edging or in containers. Creates a dense mat of color at this spacing.
Care Guide
- Feeding
- Balanced liquid feed fortnightly. Keep consistently moist.
- Watch for
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- Slugs
- Damping off (seedlings)
- Generally trouble-free
Pests & Diseases
Pest Slugs and Snails
Identification: Irregular holes in leaves and stems, seedlings eaten overnight, slime trails on soil and foliage
- Beer traps near planting areas
- Copper tape around containers and hanging baskets
- Nematode biological control (Nemaslug)
- Evening hand-picking
- Ferric phosphate pellets (wildlife-safe)
Pest Aphids
Identification: Clusters of small green insects on shoot tips, sticky honeydew on leaves, distorted new growth
- Blast off with a jet of water
- Encourage ladybirds and hoverflies
- Soft soap spray
- Pyrethrum-based contact insecticide
Disease Damping Off Pythium spp. / Rhizoctonia solani
Symptoms: Seedlings collapse at soil level, stems become thin and water-soaked, patches of seedlings die in trays
Treatment: Remove affected seedlings and surrounding compost. Improve ventilation immediately.
Prevention: Use clean trays and fresh compost. Sow thinly. Water from below. Ensure good air circulation. Avoid overwatering.
Disease Grey Mould (Botrytis) Botrytis cinerea
Symptoms: Fluffy grey mould on stems and leaves, often starting on dead flowers or damaged tissue, plants rot from the base
Treatment: Remove affected growth and dead flowers promptly. Improve air circulation.
Prevention: Deadhead regularly. Space plants to allow airflow. Avoid overhead watering. Remove dead foliage.
Growing Conditions
| Min. soil temperature | 10°C |
| Germination temperature | 18–24°C |
| Base growth temperature | 8°C |
| Min. daylength to start | 10.5h |
| Photoperiod sensitivity | day neutral |
Frequently Asked Questions
- How far apart should I plant Lobelia?
- Plant Lobelia 15cm apart with 20cm between rows.
- When does Lobelia flower?
- Lobelia typically flowers approximately 70 days after transplanting.
- Is Lobelia frost hardy?
- Lobelia is classified as Half Hardy.
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