Troubleshooting
Thunberg's Cycad problems — and how to fix them
Thunberg's Cycad (Encephalartos longifolius) 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.
Scale insects
One of the most prevalent cycad pests; infestations of cycad aulacaspis scale (Aulacaspis yasumatsui) in particular can severely damage fronds. Apply horticultural oil at 2-week intervals during crawler stage in spring; systemic imidacloprid drenches provide longer-term control.
Crown rot in wet winters
In cold, wet climates in ground or container culture, standing water around the crown during winter can cause rotting. Improve drainage by planting on a raised mound; in containers, tilt the pot slightly to shed water from the crown. Apply a preventative copper-based fungicide in autumn.
Leaflet yellowing after transplanting
Transplant shock is common in this slow-growing cycad; the plant may yellow or abort fronds after repotting or garden planting. Minimise root disturbance, water in with a dilute rooting solution, and withhold fertiliser for 8 weeks post-transplant. New flushes will appear once roots re-establish.
Prevent thunberg's cycad problems before they start
Most thunberg's cycad issues are care-mismatch, not bad luck. Dial in the basics:
Looking for thunberg's cycad in general rather than its problems? Read the full thunberg's cycad care guide — light, water, soil and feeding.
Thunberg's Cycad problems — FAQ
Why is my thunberg's cycad scale insects?
One of the most prevalent cycad pests; infestations of cycad aulacaspis scale (Aulacaspis yasumatsui) in particular can severely damage fronds. Apply horticultural oil at 2-week intervals during crawler stage in spring; systemic imidacloprid drenches provide longer-term control.
Why is my thunberg's cycad crown rot in wet winters?
In cold, wet climates in ground or container culture, standing water around the crown during winter can cause rotting. Improve drainage by planting on a raised mound; in containers, tilt the pot slightly to shed water from the crown. Apply a preventative copper-based fungicide in autumn.
Why is my thunberg's cycad leaflet yellowing after transplanting?
Transplant shock is common in this slow-growing cycad; the plant may yellow or abort fronds after repotting or garden planting. Minimise root disturbance, water in with a dilute rooting solution, and withhold fertiliser for 8 weeks post-transplant. New flushes will appear once roots re-establish.