Troubleshooting
Alaska Mix Nasturtium problems — and how to fix them
Alaska Mix Nasturtium (Tropaeolum majus) 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.
Aphids (blackfly)
Nasturtiums are notorious aphid magnets — sometimes used as trap crops deliberately. For ornamental use, spray with insecticidal soap or a jet of water.
Caterpillars (Large White butterfly)
Larvae defoliate plants rapidly; pick off by hand or use Bacillus thuringiensis (Bt) spray.
Powdery mildew
Appears in late summer on stressed plants; improve air circulation and remove affected leaves.
Slugs
Seedlings are vulnerable; use physical barriers or iron phosphate pellets.
Poor flowering in rich soil
The most common issue; avoid adding compost or fertiliser to the planting area.
Prevent alaska mix nasturtium problems before they start
Most alaska mix nasturtium issues are care-mismatch, not bad luck. Dial in the basics:
Alaska Mix Nasturtium problems — FAQ
Why is my alaska mix nasturtium aphids (blackfly)?
Nasturtiums are notorious aphid magnets — sometimes used as trap crops deliberately. For ornamental use, spray with insecticidal soap or a jet of water.
Why is my alaska mix nasturtium caterpillars (large white butterfly)?
Larvae defoliate plants rapidly; pick off by hand or use Bacillus thuringiensis (Bt) spray.
Why is my alaska mix nasturtium powdery mildew?
Appears in late summer on stressed plants; improve air circulation and remove affected leaves.
Why is my alaska mix nasturtium slugs?
Seedlings are vulnerable; use physical barriers or iron phosphate pellets.
Why is my alaska mix nasturtium poor flowering in rich soil?
The most common issue; avoid adding compost or fertiliser to the planting area.