Does your fern have shriveled, brown fronds or a bleached, discolored appearance? We know that people are susceptible to sunburn, but we don’t think of plants as being able to get sunburned as well.
It’s a common problem. When shade-loving plants like ferns are put into a sunny situation, their fronds shrivel around the edges, and their leaf color may become pale and bleached. This may be because you misjudged the amount of light the location gets, or it could happen as a result of a tree being pruned and letting in more light than the plant is used to.
This can also happen with new plants. If a plant’s been under cover in a greenhouse and hasn’t been properly “hardened off”, it can get sunburnt, even if that variety would ordinarily do well with that amount of light.
Here are some photos so you can compare and contrast healthy with sunburned ferns:
Happy tassel fern:
Tassel fern with sunburn:
Happy autumn fern:
Autumn fern with sunburn:
Now, this browning due to sunburn isn’t to be confused with the normal shedding of leaves. Ferns usually retain their leaves for 1-2 years, and then the oldest leaves usually turn brown and die back. You know you have a problem if your fern fronds start looking funky sooner than that. The new growth should stay looking green and attractive for at least a year.
Normal browning of fern fronds usually occurs on the oldest fronds that are closest to the base. When dealing with sunburn, the fronds that are browning are the ones at the top of the plant that are exposed to light. If you shift a brown frond, the ones beneath it are usually nice and green.
You can see in this photo of sword ferns in the wild, that the natural die-off of fern fronds happens on the lowest fronds only:
So, what do you do if you suspect your plant is sunburnt?
First, make sure it’s not a watering issue. Too little water as well as too much can cause the same issue of leaves going brown before they are supposed to or shriveling at the edges. Is the soil soggy, or very dry? If so, fix that issue before assuming sunburn is the problem, and wait to see whether the new leaves that unfurl over the next six months or so develop the problem as well. If they do, it is likely sunburn and the plant will need to be moved to a shadier location.
Second, if it’s a newly purchased plant, sometimes just giving it time to settle in and get acclimated is enough to solve a mild case of sunburn. While the plant can’t repair any leaves that have already been damaged, any new fronds that unfurl should stay healthy and green. If they too become damaged either right away or over the course of a few months, you probably need to move the plant.
Once you move the plant to a new location, it should settle in quickly. After the first month, any new fronds that unfurl should come out looking healthy and green, and should stay that way for at least a year.
Ferns are low-maintenance, easy-care plants that rarely suffer from pests or disease. If you give them the light and water they prefer, they’ll perform well for you for years to come.
Read about my favorite ferns here.
Check out a great book about diagnosing garden problems easily, What’s Wrong With My Plant? by Deardorff and Wadsworth.