Cooper’s fern, Lacy tree fern
Although very graceful ornamental tree ferns all Cyathea species are greenhouse plants and are not hardy outdoors as many have discovered the hard way, even in Cornwall, in the periods of warm winters between 2012 and March 2018 when the ‘Beast from the East’ appeared. They are most definitely frost tender and, unlike Dicksonia antarctica, the Australian and New Zealand tree fern, they will not regrow their fronds from the crown of the trunk if these are frosted or blown away in the winter.
C. cooperi is a fast growing tree fern with a slender trunk and bi-pinnate fronds which, in maturity, can be 10-12ft long. The new fronds have white scaly stalks at first which adds to this plant as a standout feature in a larger conservatory or greenhouse. Over time the trunk may grow to 6-8ft in height.
In the wild in Australia these tree ferns grow below the understory of the tree canopy above where it is shady, damp and humid. You need to try to create these conditions in your greenhouse with shading, misting and a good watering of the trunk and leaves from time to time on hot days.
In large containers the soil provided for these tender tree ferns should be a mixture of loam, sharp sand and leaf mould. This replicates what they grow best in in their native habitat. Liquid fertiliser, added monthly, will speed the growth of the trunks and giant fronds.
We sometimes also have small stocks of C. medullaris and C. dealbata. These species are equally tender and require exactly the same treatment.
