We leave for about 5 months in the winter and by the time we
get back our sword ferns have sprouted and it’s hard to prune the old
fronds out without cutting off the new ones. These ferns are in a fairly
protected area, so I was wondering if it would be okay to cut off the old
fronds in October before we leave? Also would it help if we just cut the
old fronds and lay them over the plant to help protect it over the
winter?
There are some slight differences of opinion on cutting back sword ferns.
It might be fine to cut the old fronds this fall and leave them as
protection over the winter, but it isn’t really necessary to cut them
back until early spring, if at all. The local web site for Great Plant
Picks recommends cutting sword ferns to the ground in late winter, or
only cutting back every 3 years or so on plants growing in poor soil:
Paghat’s Garden, another local gardening site recommends only cutting away dead fronds. Excerpt:
It was once believed it was necessary to cut all the fronds off in
February immediately before new growth begins, but it is now the
recommendation to only trim dead fronds. By April when the fiddleheads
are thickly erupting, any of last year’s fronds that have lost their
beauty should be removed, but only for looks’ sake, removing up to as
many as all of them. They’ll soon enough be replaced by new. Just don’t
remove the fronds before winter’s final frosts, as the reason this fern
adapted itself to keeping its fronds green at least until winters’ end is
to shelter & protect the humping crown from excessive cold or from
sunlight in winter when deciduous trees might not adequately shade the
rootcrown.
Since your plants are in a protected area, you might be able to go ahead
with your October trimming, but really the main reason to trim is an
aesthetic one, so it isn’t absolutely necessary.