Troubleshooting
Jerusalem Sage problems — and how to fix them
Jerusalem Sage (Phlomis fruticosa) 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.
Crown rot from winter wet
The primary threat, especially on heavy or clay soils in wet UK winters. Cold, waterlogged soil causes fungal crown rot (Phytophthora, Pythium). Plant in free-draining ground, on a gentle slope, or in a raised bed; improve clay soils heavily with grit before planting.
Leafhoppers
Phlomis fruticosa is specifically noted by the RHS as susceptible to leafhopper (Eupteryx spp.) damage, which causes coarse, pale mottling on the upper leaf surface as the insects feed on the underside. In most cases, a healthy plant tolerates moderate leafhopper activity without lasting harm; heavy infestations can be controlled with an appropriate insecticide applied to the undersides of leaves.
Floppy, over-tall growth after several years
Mature plants can become rangy and open-stemmed, particularly after mild, damp winters. Cut back hard by one-third to one-half in mid-spring to rejuvenate the shrub — unlike Cistus, Phlomis fruticosa responds well to renovation pruning and will regenerate vigorously from the base.
Prevent jerusalem sage problems before they start
Most jerusalem sage issues are care-mismatch, not bad luck. Dial in the basics:
Jerusalem Sage problems — FAQ
Why is my jerusalem sage crown rot from winter wet?
The primary threat, especially on heavy or clay soils in wet UK winters. Cold, waterlogged soil causes fungal crown rot (Phytophthora, Pythium). Plant in free-draining ground, on a gentle slope, or in a raised bed; improve clay soils heavily with grit before planting.
Why is my jerusalem sage leafhoppers?
Phlomis fruticosa is specifically noted by the RHS as susceptible to leafhopper (Eupteryx spp.) damage, which causes coarse, pale mottling on the upper leaf surface as the insects feed on the underside. In most cases, a healthy plant tolerates moderate leafhopper activity without lasting harm; heavy infestations can be controlled with an appropriate insecticide applied to the undersides of leaves.
Why is my jerusalem sage floppy, over-tall growth after several years?
Mature plants can become rangy and open-stemmed, particularly after mild, damp winters. Cut back hard by one-third to one-half in mid-spring to rejuvenate the shrub — unlike Cistus, Phlomis fruticosa responds well to renovation pruning and will regenerate vigorously from the base.