Ferns are a beautiful plant addition to both indoor and outdoor gardens. Too often though, they have challenges that cause them to turn yellow and sometimes brown on the leaves.
It isn’t alarming for a few fronds to be light green or yellow on a plant. Sometimes new fronds are lighter in color than the more mature ones.
They will darken with age. Older fronds at the base of the plant may turn yellow and then brown and drop off.
This is normal and not a cause for alarm. If you notice a lot of the fronds turning color, then it is time to evaluate the possible cause. There are several reasons why this could be happening.
1. Watering Challenges
Ferns require their soil to be evenly moist. They cannot be too moist or too dry. A common issue with caring for ferns is to overwater or underwater them.
Either of these things can make the fronds turn light green and then yellow and wilt. I water mine only when the soil is dry on top and I always water from the top.
My pots always have draining holes, so the roots don’t sit in water. This will cause the plant to yellow or wilt. I don’t water at all if the soil is still damp to the touch.
2. Too much light or not enough light
Ferns do best in the shade. Sometimes when a fern is subjected to a bright environment it will cause the fronds to turn light and yellow.
In direct sunlight, a fern can turn brown from sun damage. It will look scorched and dry if this happens.
Ferns need to be in indirect light for small periods during the day. If a room is too dark, the fronds will turn, and eventually, the plant will wilt and die.
When I brought my last greenhouse-grown fern home, I naively tried to move it outdoors without hardening it first.
The fronds turned light green and then yellow even though I had placed them in the shade.
In order to prevent this, it is a good idea to harden the fern first by putting it outside in the shade for short periods of time each day, adding more time daily. I start with one hour and add an hour each day.
3. Temperature Issue
Sometimes ferns turn brown if they are cold. It is normal for an outdoor fern to turn yellow and then brown as the plant goes into its dormant winter season. Indoors, however, ferns do not follow this cycle.
They can turn brown on the tips if the air temperature is too cool for them. Ideally, the day temperature should be between 65 and 75 degrees, but it can drop up to 10 degrees in the evening. I
f it is warmer than that, the fern will need to be watered more to prevent the leaves from turning yellow.
Ferns will sometimes turn yellow and wilt if there is not enough humidity in the air. A fern room should never be less than 50% humidity and can go as high as 80% or more to keep them bright green and healthy.
Ferns are susceptible to various types of pests including scale insects, mealybugs, and mites. An infestation can cause the fronds to turn light greenish-yellow in color.
Inspect your plant carefully for an infestation. Ferns are easily damaged by pesticides, so it is better to use something natural to manage the infestation. I use a cotton swab soaked in alcohol or Neem oil on my ferns.
You will be able to tell right away if the fern has spider mites. These pests weave webs in the fronds, just like a spider.
If the plant is yellow and has a speckled look, this can also point to spider mites, even if the webs aren’t visible to you.
Sometimes when a fern turns yellow, it is due to a lack of nitrogen or too much nitrogen in its growing soil.
You can give the fern a balanced houseplant food. 20-20-20 or 20-10-20 is ideal for a fern as they are relatively light eaters.
If the fronds are yellow it can be a lack of nitrogen but if the tips look burned or brown, this can be a sign of too much.
I add organic compost, pine bark, or perlite to the soil for my ferns. It seems to keep the pH balance optimal for them.
6. Root Problems
A fern can turn yellow from being rootbound in its pot. If none of the other interventions have fixed the issue, lift the pot, and take a peek at the roots.
If the roots are slimy and black, root rot is the culprit to its yellowing leaves. In this case, prune the dead roots, cut back on watering, and change the soil to a fast-draining soil.
If the roots are coiled and wrapped around each other in a tight ball, the culprit to the yellowing leaves is likely that the plant is root-bound. In this case, you will need to repot the plant in a pot that is at least 2 inches bigger than it’s current one.
7. Transplant Shock
Ferns are notorious for turning brown at the tips and suffering stress after transplanting. Although there is no easy way to avoid this, it is always a good idea to transplant in the spring whenever possible.
This will lessen the stress on the plants and the fronds are more likely to stay bright green and healthy.
To transplant it with as little stress as possible, I dig around in the root a bit before removing the plant from the soil.
I try to remove as much of the root system as possible and I am very gentle when I lift it out with my two trowels so as not to damage their delicate roots.
The new hole should be 2 inches wider than the root system and as deep. This will help the plant settle and keep its fronds from getting stressed and turning brown.
I find ferns to be a bit of a fussy plant to look after but with these 7 tips, you will have all the bases covered to have beautiful and lush plants that are a gorgeous addition to any garden, inside or out.
If any of your ferns are yellowing, this list will help you to troubleshoot, identify, and remedy the causes of yellowing on ferns.
Marcel runs the place around here. He has a deep passion for houseplants & gardening and is constantly on the lookout for yet another special plant to add to his arsenal of houseplants, succulents & cacti.
Marcel is also the founder of Iseli International Commerce, a sole proprietorship company that publishes a variety of websites and online magazines.