Troubleshooting
Dwarf nasturtium problems — and how to fix them
Dwarf nasturtium (Tropaeolum minus) 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.
Aphid infestations
Nasturtiums are highly attractive to blackfly and aphids (Aphis fabae), particularly on young growth. Many gardeners use them as a sacrificial trap crop to draw aphids away from vegetables. Knock off colonies with a strong jet of water or apply insecticidal soap.
Powdery mildew
White powdery coating on leaves in hot, dry, overcrowded conditions later in the season. Improve air circulation by thinning plants, avoid wetting foliage, and remove badly affected growth. Plants often decline naturally at season's end anyway.
Caterpillar damage (Large white butterfly)
Larvae of Pieris brassicae can strip nasturtium foliage as they are also attracted to Tropaeolaceae. Hand-pick caterpillars and eggs from leaf undersides, or cover with insect-proof mesh to prevent butterfly egg-laying.
Prevent dwarf nasturtium problems before they start
Most dwarf nasturtium issues are care-mismatch, not bad luck. Dial in the basics:
Looking for dwarf nasturtium in general rather than its problems? Read the full dwarf nasturtium care guide — light, water, soil and feeding.
Dwarf nasturtium problems — FAQ
Why is my dwarf nasturtium aphid infestations?
Nasturtiums are highly attractive to blackfly and aphids (Aphis fabae), particularly on young growth. Many gardeners use them as a sacrificial trap crop to draw aphids away from vegetables. Knock off colonies with a strong jet of water or apply insecticidal soap.
Why is my dwarf nasturtium powdery mildew?
White powdery coating on leaves in hot, dry, overcrowded conditions later in the season. Improve air circulation by thinning plants, avoid wetting foliage, and remove badly affected growth. Plants often decline naturally at season's end anyway.
Why is my dwarf nasturtium caterpillar damage (large white butterfly)?
Larvae of Pieris brassicae can strip nasturtium foliage as they are also attracted to Tropaeolaceae. Hand-pick caterpillars and eggs from leaf undersides, or cover with insect-proof mesh to prevent butterfly egg-laying.