Troubleshooting
Grosso lavandin problems — and how to fix them
Grosso lavandin (Lavandula x intermedia 'Grosso') 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.
Botrytis grey mould
Can devastate flower spikes in wet, cool summers. Harvest spikes before fully open, improve spacing, and avoid wetting flowers. Remove and destroy infected material promptly. Fungicide sprays are rarely warranted in well-managed plantings.
Root rot
The single greatest killer of 'Grosso' outside its native range. Overwatering or poor drainage causes rapid collapse. Site on a slope or raised mound, plant through gravel mulch, and never irrigate established plants unless in severe drought.
Leafhoppers and froghoppers
In the UK, lavender leafhopper (Eupteryx decemnotata) and cuckoo spit (froghopper) are common pests. Leafhoppers cause pale mottling; remove by hand and spray with insecticidal soap. Cuckoo spit can be washed off with water.
Prevent grosso lavandin problems before they start
Most grosso lavandin issues are care-mismatch, not bad luck. Dial in the basics:
Looking for grosso lavandin in general rather than its problems? Read the full grosso lavandin care guide — light, water, soil and feeding.
Grosso lavandin problems — FAQ
Why is my grosso lavandin botrytis grey mould?
Can devastate flower spikes in wet, cool summers. Harvest spikes before fully open, improve spacing, and avoid wetting flowers. Remove and destroy infected material promptly. Fungicide sprays are rarely warranted in well-managed plantings.
Why is my grosso lavandin root rot?
The single greatest killer of 'Grosso' outside its native range. Overwatering or poor drainage causes rapid collapse. Site on a slope or raised mound, plant through gravel mulch, and never irrigate established plants unless in severe drought.
Why is my grosso lavandin leafhoppers and froghoppers?
In the UK, lavender leafhopper (Eupteryx decemnotata) and cuckoo spit (froghopper) are common pests. Leafhoppers cause pale mottling; remove by hand and spray with insecticidal soap. Cuckoo spit can be washed off with water.