Troubleshooting
Crystal Palace lobelia problems — and how to fix them
Crystal Palace lobelia (Lobelia erinus 'Crystal Palace') is generally forgiving once you match its basics, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Heat collapse and die-back
Lobelia erinus is a cool-season plant and goes dormant or dies back in sustained temperatures above 27°C — shear plants back by half, keep moist and they often recover when temperatures drop.
Grey mould (Botrytis cinerea)
Dense flower heads and moist, still conditions encourage Botrytis — improve airflow, avoid overhead watering and remove spent blooms promptly.
Damping off in seedlings
Tiny lobelia seedlings are prone to damping off fungi when sown too thickly and kept too wet — sow thinly on the surface of moist, sterile seed compost and provide good light and airflow.
Prevent crystal palace lobelia problems before they start
Most crystal palace lobelia issues are care-mismatch, not bad luck. Dial in the basics:
- Common edging lobelia problems — the species this cultivar belongs to
- Common crystal palace lobelia problems — our other guide for the same plant
- What's wrong with my plant? — the diagnosis apps compared
- Crystal Palace lobelia watering schedule
- Crystal Palace lobelia light requirements
- Best soil mix for crystal palace lobelia
- Crystal Palace lobelia temperature & humidity
- Full crystal palace lobelia care guide
Looking for crystal palace lobelia in general rather than its problems? Read the full crystal palace lobelia care guide — light, water, soil and feeding.
Crystal Palace lobelia problems — FAQ
Why is my crystal palace lobelia heat collapse and die-back?
Lobelia erinus is a cool-season plant and goes dormant or dies back in sustained temperatures above 27°C — shear plants back by half, keep moist and they often recover when temperatures drop.
Why is my crystal palace lobelia grey mould (botrytis cinerea)?
Dense flower heads and moist, still conditions encourage Botrytis — improve airflow, avoid overhead watering and remove spent blooms promptly.
Why is my crystal palace lobelia damping off in seedlings?
Tiny lobelia seedlings are prone to damping off fungi when sown too thickly and kept too wet — sow thinly on the surface of moist, sterile seed compost and provide good light and airflow.