Troubleshooting
Green Shiso problems — and how to fix them
Green Shiso (Perilla frutescens var. crispa f. viridis) 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.
Premature bolting
Triggered by long days, heat stress, or drought. Pinch out flower spikes as soon as they appear to extend the leaf harvest by several weeks. Providing afternoon shade in midsummer also delays bolting.
Aphids on young shoots
Soft new growth is a favourite aphid target, especially in sheltered conditions. Knock off with a strong water spray or apply an insecticidal soap solution. Encourage lacewings and ladybirds as natural predators.
Damping off in cool, wet conditions
Seedlings are susceptible to damping off if sown in cold, waterlogged compost. Sow only when soil temperature is above 18°C, use sterile seed compost, and ensure good drainage and airflow around seedling trays.
Prevent green shiso problems before they start
Most green shiso issues are care-mismatch, not bad luck. Dial in the basics:
Green Shiso problems — FAQ
Why is my green shiso premature bolting?
Triggered by long days, heat stress, or drought. Pinch out flower spikes as soon as they appear to extend the leaf harvest by several weeks. Providing afternoon shade in midsummer also delays bolting.
Why is my green shiso aphids on young shoots?
Soft new growth is a favourite aphid target, especially in sheltered conditions. Knock off with a strong water spray or apply an insecticidal soap solution. Encourage lacewings and ladybirds as natural predators.
Why is my green shiso damping off in cool, wet conditions?
Seedlings are susceptible to damping off if sown in cold, waterlogged compost. Sow only when soil temperature is above 18°C, use sterile seed compost, and ensure good drainage and airflow around seedling trays.