Troubleshooting
Red amaranth problems — and how to fix them
Red amaranth (Amaranthus cruentus) 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
Dense colonies of black or green aphids, especially on new growth and flower plumes. Blast off with a strong jet of water or apply insecticidal soap. Companion-plant with nasturtium as a trap crop.
Damping-off in seedlings
Young seedlings collapse at soil level in cold, wet, or poorly ventilated conditions. Sow in warm (21°C+) well-drained compost. Avoid overwatering and provide good air circulation during germination.
Cercospora leaf spot
Circular brown or tan spots with darker margins on older leaves, caused by Cercospora fungal species. Remove affected foliage, improve airflow, and rotate planting sites. Generally not fatal to established plants.
Prevent red amaranth problems before they start
Most red amaranth issues are care-mismatch, not bad luck. Dial in the basics:
Red amaranth problems — FAQ
Why is my red amaranth aphid infestations?
Dense colonies of black or green aphids, especially on new growth and flower plumes. Blast off with a strong jet of water or apply insecticidal soap. Companion-plant with nasturtium as a trap crop.
Why is my red amaranth damping-off in seedlings?
Young seedlings collapse at soil level in cold, wet, or poorly ventilated conditions. Sow in warm (21°C+) well-drained compost. Avoid overwatering and provide good air circulation during germination.
Why is my red amaranth cercospora leaf spot?
Circular brown or tan spots with darker margins on older leaves, caused by Cercospora fungal species. Remove affected foliage, improve airflow, and rotate planting sites. Generally not fatal to established plants.