Troubleshooting
Spiraea x vanhouttei problems — and how to fix them
Spiraea x vanhouttei (Spiraea x vanhouttei) 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.
Poor flowering after pruning
Because it blooms on old wood, pruning in late winter or early spring removes the flower buds. Prune only right after flowering finishes.
Powdery mildew
White powdery film on leaves in humid, crowded conditions. Improve air circulation, avoid overhead watering and thin congested stems.
Aphids
Clusters on soft new shoots can distort growth and leave sticky honeydew. Hose off or treat with insecticidal soap; natural predators usually keep them in check.
Legginess and bare base
Old, unpruned plants flop and go bare at the centre. Renovate by cutting a third of the oldest stems to the ground each year after flowering.
Prevent spiraea x vanhouttei problems before they start
Most spiraea x vanhouttei issues are care-mismatch, not bad luck. Dial in the basics:
Looking for spiraea x vanhouttei in general rather than its problems? Read the full spiraea x vanhouttei care guide — light, water, soil and feeding.
Spiraea x vanhouttei problems — FAQ
Why is my spiraea x vanhouttei poor flowering after pruning?
Because it blooms on old wood, pruning in late winter or early spring removes the flower buds. Prune only right after flowering finishes.
Why is my spiraea x vanhouttei powdery mildew?
White powdery film on leaves in humid, crowded conditions. Improve air circulation, avoid overhead watering and thin congested stems.
Why is my spiraea x vanhouttei aphids?
Clusters on soft new shoots can distort growth and leave sticky honeydew. Hose off or treat with insecticidal soap; natural predators usually keep them in check.
Why is my spiraea x vanhouttei legginess and bare base?
Old, unpruned plants flop and go bare at the centre. Renovate by cutting a third of the oldest stems to the ground each year after flowering.