Troubleshooting
Penstemon 'Garnet' problems — and how to fix them
Penstemon 'Garnet' (Penstemon 'Garnet') 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.
Winter losses from cold, wet soil
The main cause of death is waterlogged ground in cold winters rather than frost alone. Plant in free-draining soil and avoid cutting back hard until spring for crown protection.
Leggy, sparse flowering
Too much shade or lack of deadheading reduces bloom. Site in full sun and deadhead spent spikes to prolong flowering into autumn.
Powdery mildew
A white coating appears in humid, crowded conditions. Improve air flow, avoid overhead watering and space plants adequately.
Plant becoming woody and shy-flowering
Older clumps grow woody and bloom less. Renew every few years from cuttings, as penstemons are not long-lived.
Prevent penstemon 'garnet' problems before they start
Most penstemon 'garnet' issues are care-mismatch, not bad luck. Dial in the basics:
Looking for penstemon 'garnet' in general rather than its problems? Read the full penstemon 'garnet' care guide — light, water, soil and feeding.
Penstemon 'Garnet' problems — FAQ
Why is my penstemon 'garnet' winter losses from cold, wet soil?
The main cause of death is waterlogged ground in cold winters rather than frost alone. Plant in free-draining soil and avoid cutting back hard until spring for crown protection.
Why is my penstemon 'garnet' leggy, sparse flowering?
Too much shade or lack of deadheading reduces bloom. Site in full sun and deadhead spent spikes to prolong flowering into autumn.
Why is my penstemon 'garnet' powdery mildew?
A white coating appears in humid, crowded conditions. Improve air flow, avoid overhead watering and space plants adequately.
Why is my penstemon 'garnet' plant becoming woody and shy-flowering?
Older clumps grow woody and bloom less. Renew every few years from cuttings, as penstemons are not long-lived.