Troubleshooting
Golden Alexanders problems — and how to fix them
Golden Alexanders (Zizia aurea) 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 (Aphis saniculae / Aphis thaspii)
Two sap-sucking aphid species are specific to Zizia; infestations are usually minor and controlled naturally by ladybirds and hoverfly larvae. A firm spray of water dislodges heavy colonies.
Black swallowtail caterpillars
Larvae of the eastern black swallowtail (Papilio polyxenes) feed on the foliage; this is ecologically desirable as Zizia is a primary host plant. Tolerate feeding unless defoliation is severe on young plants.
Failure to transplant / taproot damage
The deep, fleshy taproot makes established plants very difficult to move successfully; always plant from container stock in spring and do not disturb once settled.
Prevent golden alexanders problems before they start
Most golden alexanders issues are care-mismatch, not bad luck. Dial in the basics:
Golden Alexanders problems — FAQ
Why is my golden alexanders aphids (aphis saniculae / aphis thaspii)?
Two sap-sucking aphid species are specific to Zizia; infestations are usually minor and controlled naturally by ladybirds and hoverfly larvae. A firm spray of water dislodges heavy colonies.
Why is my golden alexanders black swallowtail caterpillars?
Larvae of the eastern black swallowtail (Papilio polyxenes) feed on the foliage; this is ecologically desirable as Zizia is a primary host plant. Tolerate feeding unless defoliation is severe on young plants.
Why is my golden alexanders failure to transplant / taproot damage?
The deep, fleshy taproot makes established plants very difficult to move successfully; always plant from container stock in spring and do not disturb once settled.