Pocket Botanist
Check these first
- Observe how many hours of direct or bright light the plant receives daily.
- Check if the stems are leaning heavily toward a window or a specific side of the garden.
- Feel the soil to ensure it is consistently damp rather than drying out completely.
Likely causes
Insufficient light
Most likelyHow to tell: The stems are stretching out and leaning toward the nearest light source while the leaves look pale or sparse.
What to do: Move your plant to a spot that receives at least 6 hours of bright, indirect light or partial sun. If you are growing it indoors, place it directly in a south or east facing window.
Excessive heat
PossibleHow to tell: The plant grows rapidly and weakly during a heatwave, causing the stems to flop over.
What to do: Provide some afternoon shade during the hottest part of the summer to keep the soil cool. Ensure you are watering every 2 to 4 days to keep the roots hydrated and the plant sturdy.
Find out what's wrong with your great blue lobelia
The list above covers the usual causes. Pocket Botanist looks at a photo of your actual plant and tells you the likely cause, how serious it is, and what to try first. Identification and a health check are free.
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When to worry
Worry if the stems are so weak they cannot hold up the flowers or if the plant is collapsing entirely. It is normal for the plant to grow tall and reach for light if it is planted in a shaded woodland area.
Stopping it coming back
Place your lobelia in a location with consistent partial sun and pinch back the tips of the stems in late spring to encourage a bushier shape.
Great blue lobelia: leggy growth? Check yours with a photo
Every plant is a little different. Take a photo of your great blue lobelia and Pocket Botanist tells you which cause is most likely, how serious it is, and what to try first. A few checks a day are free. Save the plant and you get care reminders timed for it.
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Questions people ask
- Can I cut back my leggy lobelia?
- Yes, you can trim back the stems by about one third to encourage the plant to branch out and grow more compactly. Do this in late spring before the main flowering period.
- Will a leggy plant still bloom?
- It might still produce some flowers, but the blooms will likely be smaller and the stems may struggle to stay upright. Providing more light will help the plant focus its energy on stronger stems and more vibrant flowers.
More problems with Great blue lobelia
Back to the Great blue lobelia guide
This article was generated with AI on from the plant’s care profile and is general information, not horticultural advice. Read about how we build these guides.