I hae a 5ft tree fern that I have outside in the summer and in a cool greenhouse in the winter. I had always been told that these do not develop roots from the base of the trunk and so have made no particular efforts to water here (it is in a moderate size pot), just at the crown.However, on browsing these forums I see this is not at all true! Every year the depression at the crown where the fronds emerge from gets smaller and more constricted. Is this due to underwatering / not having a basal root system? This year it seems very reluctant to produce any fronds (I can feel some in the crown, but they do not appear to be getting bigger). Any thoughts how I might bring this back to health? I live in the UK (Midlands).