Troubleshooting
Small-flowered Cape Primrose problems — and how to fix them
Small-flowered Cape Primrose (Streptocarpus micranthus) is generally low-drama, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Stem base collar rot
Fungal rot at the soil surface causes the stem to turn brown and soft at its base, collapsing the plant; this is triggered by compost kept too wet around the stem. Use a very well-drained mix, water from below, and top-dress with a layer of grit at the stem base.
Powdery mildew
White powdery fungal coating appears on leaves in warm, poorly ventilated conditions; the small, closely spaced leaves of this species make it susceptible. Improve airflow, reduce humidity slightly, and apply a potassium bicarbonate spray at the first signs.
Prevent small-flowered cape primrose problems before they start
Most small-flowered cape primrose issues are care-mismatch, not bad luck. Dial in the basics:
Small-flowered Cape Primrose problems — FAQ
Why is my small-flowered cape primrose stem base collar rot?
Fungal rot at the soil surface causes the stem to turn brown and soft at its base, collapsing the plant; this is triggered by compost kept too wet around the stem. Use a very well-drained mix, water from below, and top-dress with a layer of grit at the stem base.
Why is my small-flowered cape primrose powdery mildew?
White powdery fungal coating appears on leaves in warm, poorly ventilated conditions; the small, closely spaced leaves of this species make it susceptible. Improve airflow, reduce humidity slightly, and apply a potassium bicarbonate spray at the first signs.