Tree Fern fronds detaching

jez2

Hi, I have had a large (6ft) potted Dicksonia Antarctica for about 7 years now in the South of the UK, it always seems pretty healthy and always produces a full set of new fronds each year.
Normally old growth will go brown and droop, as normal, at which point I will cut the stem, leaving 5 or 6 inches to help form a sturdy crown.
This year however, just recently, old fronds have been dropping, not dropping, and detaching themselves from the trunk at the base of the frond before turning brown. It's as if they have lost their connection to the main trunk and fallen with their weight, the connection to the trunk no longer able to secure them 
 Also some of the older, previous years old growth (stems that had been cut) are easy to separate from the trunk, as if they are no longer gripping onto it.
Some of these are turning black before separating:



Has anyone experienced similar behaviour?
Not sure if this is a sign of a problem or not.
Thanks for any response,
Jez. 

bertrand-mabel

Lovely specimen @jez2 . It looks like you have it indoors (a greenhouse?). Is it getting enough water down the "trunk"?

Ours are outside and even though they were wrapped up near the crown we still watered them if we had no rain for some time.

They are unwrapped now and not showing signs that you describe.

We do are you do with the old stems not cutting them off as in nature they will fall against the "trunk" and finally fall off when they are ready.

jez2

Thanks for the response, it is actually outdoors, but in a small enclosed courtyard, which is great as it cuts out any wind, which I think these guys aren't that keen on.
Maybe this is, as you say, the natural way for the old fronds to drop off, it's just that all previous ones that died off on mine would turn brown first, whereas these are still green (although starting to turn). Then they would droop, still well attached to the trunk.
I guess I will probably only start to worry if this happens to fully green leaves.
Good luck with yours!