Troubleshooting
Sidebells Penstemon problems — and how to fix them
Sidebells Penstemon (Penstemon secundiflorus) 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
The most common killer. Caused by poor drainage or overwatering, especially in heavy clay soils. Plant on a slope or raise the bed to ensure water moves away from the crown rapidly.
Powdery mildew
Can appear in humid summers or where air circulation is restricted. Avoid overhead watering; choose sunny, open sites. Affected foliage rarely kills established plants.
Failure to bloom
Usually caused by insufficient direct sunlight or excessive soil fertility from heavy fertilizing. Move to a sunnier location and stop amending with nitrogen-rich composts.
Prevent sidebells penstemon problems before they start
Most sidebells penstemon issues are care-mismatch, not bad luck. Dial in the basics:
Looking for sidebells penstemon in general rather than its problems? Read the full sidebells penstemon care guide — light, water, soil and feeding.
Sidebells Penstemon problems — FAQ
Why is my sidebells penstemon crown rot?
The most common killer. Caused by poor drainage or overwatering, especially in heavy clay soils. Plant on a slope or raise the bed to ensure water moves away from the crown rapidly.
Why is my sidebells penstemon powdery mildew?
Can appear in humid summers or where air circulation is restricted. Avoid overhead watering; choose sunny, open sites. Affected foliage rarely kills established plants.
Why is my sidebells penstemon failure to bloom?
Usually caused by insufficient direct sunlight or excessive soil fertility from heavy fertilizing. Move to a sunnier location and stop amending with nitrogen-rich composts.