By Mowerman
East Sussex coast,
United Kingdom 
Contradiction on Gardeners World?
Last Friday (26/4) on GW Monty was removing the dead fronds from a Dicksonia tree fern. He cut them back to the bottom of the stem where they emerged from the top of the trunk.
However about this time last year he performed the same procedure on GW and advised cutting the dead fronds off leaving about 4 inches of the stem remaining. From my experience this latter method is probably correct as otherwise the trunk will, over the years, taper as it grows, as mine has done – see photo-although this may just be peculiar to my fern. Anyone have experience with exactly where to cut off the dead fronds?
3 May, 2019
It is usual to take them off as close as possible to the trunk, but without damaging any emerging fronds, so I'd say he got it right this year. No idea why he said to leave 4 inch stubs - they only die anyway, so what's the point? According to the link below, narrowing of the trunk over time is due to insufficient water at various times, especially if the tree is sited somewhere it gets sun... they do better in dappled sun or shade.
https://www.kelways.co.uk/page/tree-fern-care/79/
3 May, 2019