QuestionMy 3 Japanese painted ferns, which I planted last spring, came up and leafed out this spring, only to turn brown and shriveled after a few freezing nights. Are they dead, or just shocked back into dormancy?
AnswerJapanese Painted Fern -- 'Athyrium nipponicum Pictum' to botanists -- grows around 1 foot tall in light to full shade under brush and trees. It grows best with a constant supply of moisture, but it will tolerate short periods of drought. It is one of the most beautiful ferns you ever did see.
So it would worry anyone that one lovely spring morning, they stepped outside to greet their Ferns and found frost on the grass nearby, their Painted Ferns 'brown and shriveled'.
This went on for days?
Repeat patterns of freeze/thaw isn't just bad for leaves. It's murder on roots, as well. The heaving breaks delicate roots and leaves them open to more cold damage. You just don't see it. The chilled fronds, meantime, are frosting up as well.
One way to deal with cold damage is to keep an exposed plant 'hydrated' -- watering in this situation actually helps keep it from drying out as water moves up the stem into the leaves and evaporates, especially in windy situations. With their large surface area, fern leaves are prime candidates for this kind of damage.
A cold WINDY night makes it absolutely imperitive that you keep your Ferns well watered.
Cold-damaged individual fronds may be badly damaged by severe cold, and the worst ones should be removed. Even hardy ferns, as you have learned, can suffer cold damage, although their proximity to the ground keeps them one or two degrees warmer than taller shrubs and plants -- sometimes this is all it takes.
Dormancy is a slow, gradual process that takes weeks. Plants cannot be 'shocked' into dormancy, although that would be a nice trick if we could do it. Still, I think it is likely that new fronds will emerge for the next month or so. If so, your plants will recover. My money's on their survival mechanisms, built over millions of years. Wait and see. And keep me posted.