Monday, April 14, 2014

Dicksonia antarctica tree fern growth in the UK - an update

Three years ago I posted an entry on the growth rate of Dicksonia antarctica, the hardiest of the tree ferns.  You'll find the original here but, to summarise, I reported a growth rate of about 32in /  81cm of trunk growth in 9 years from a young, trunkless fern - with a measured rate of about 22 in / 55cm of trunk growth in the 4 years between 2007 and 2011.

Time for an update.

This morning the trunk, from ground level to the level of the growing point, measured 43in / 108cm.  Three seasons more growth have added another 11 in / 27cm in extension.  The trunk itself has thickened, with the beginnings of a broader base at ground level.

Dicksonia antarctica trunk - April 14th 2014
Slightly slower growth than previously reported, but, with four data points, it's given me a better estimate of the rate of growth of these elegant, palm like ferns.  I've revised my estimate down slightly to about 3.5-4in / 8-10cm per year.  Of course this is only based on a sample of a single plant that has spent the latter part of it's life in a fairly exposed, sunny spot.  Plants in moister, more sheltered positions in the Cornish valley gardens must have a faster growth rate.  Even so it's still quite impressive for a plant that is still very commonly advertised as growing less than 1in / 2.5cm per year.

After a few warm days the new season's growth has already started.  Here's a quick grab shot of the new fronds beginning to unroll in the centre of the trunk apex.  Poor quality but it's a bright, sunny day and worming my through the rather prickly old fronds to get a hand held shot imposed certain constraints on composition.  I'll do better when the clouds roll over and I've tidied up the dead old growth from the 2012 season.

Dicksonia antarctica fronds beginning to unroll in mid April
In the previous post I speculated that I might celebrate my 70th birthday under a crown of fronds starting above the 6ft / 180cm level. Seven more growing seasons at the revised growth rate leaves me a little short - but not by much.  I might just have to live a little longer to enjoy it.

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