A fern can vary in color and texture along the length of its leaves, but becoming brown and crispy are signs that something is seriously wrong with your fern. If your fern is turning brown and crispy, I’ll walk you through the most likely causes and what you can do to prevent each of them.
Why is my fern turning brown and crispy? Your fern can turn brown and crispy for a variety of reasons, including high heat, too much sunlight, or transplant shock. Even a pot that’s too small can cause changes in your fern’s foliage texture and color.
I’ve compiled my personal list of reasons your fern is most likely turning brown or feels crispy or even brittle. By the time you’re done reading, you’ll be able to pinpoint what could be wrong with your fern and how to fix this common fern issue!
Why Is My Fern Turning Brown and Crispy? 7 Common Causes
Ferns are considered easy-to-grow indoor plants, but they can still suffer a variety of conditions that can strip them of their appealing, vibrant green foliage.
Per the intro, let’s delve into the causes of fern browning and crisping.
Most fern species grow best in a standard room-temperature range between 65 and 75 degrees Fahrenheit by day.
In many homes and offices, it won’t get hotter than 75. If your heating and cooling systems aren’t always running though, then the temps can often creep up higher without you being aware.
Once the temperatures reach closer to 80 degrees and certainly if they exceed that, your fern is likely going to start to experience a degree of leaf burn.
The plant’s wispy foliage will begin to dry out, which will in turn cause yellowing and browning of the leaves.
Be very careful, as in temperatures of 90 degrees, many fern species will die. These conditions are far too hot for this plant.
Most people are more focused on the fern’s cold intolerance when growing this plant indoors, as it doesn’t do well in cold and breezy conditions. You should be too, but don’t forget to watch your thermostat’s higher-end as well. Both are important!
Too Much Sunlight
When it comes to how much sunlight a growing fern needs, the answers vary.
Some species do grow best in full sun aka direct sunlight. Other species prefer shadier conditions.
This information can be confusing for beginner indoor gardeners, and so they assume that every fern species must require full sunlight.
Pro Tip: Most ferns don’t require full sunlight.
If your fern is sensitive to too much sun, then the effects of prolonged direct sun exposure will become apparent quickly.
The foliage will first become brown, usually around the leaf edges and especially the tips. Without further intervention, you might come home to see your fern leaves turning black!
While a sun-scorched plant can be saved, you’d have to prune all the damaged leaves and dead fronds of your fern. Sunburned or browned leaves don’t heal or return to their original vibrant green color.
How to Know How Much Light Your Fern Needs
The only way to be sure what kind of lighting your indoor fern needs is to determine the particular fern species as soon as possible and follow its recommended lighting needs.
A second and much more satisfying and time-consuming method would be to cautiously experiment with your fern. This is done by paying close attention to your fern for days or even weeks while consistently providing the fern indirect light on as steady of a schedule as you can possibly control.
If the leaves or fronds of your fern are standing up on their own more days than they’re laying flat or appearing droopy and not becoming burnt on their tips then you’ve found the perfect amount of light your fern needs for the current stage in its growth cycle.
If the leaves of your fern are standing upright but begin to show signs of browning or becoming dried out or crispy this means that your fern needs less light than you’re currently providing it.
Whether you’re using the natural sunlight from the sun or you’re using a grow light to provide a consistent light source for your fern plant, it’s best to lower the strength of light or position the fern further away from the light slowly over a day or two.
Many indoor gardeners, myself included, have “overcorrected” by making drastic changes to the amount of light or the placement or position of their potted fern at the first site of browning.
While I completely understand the desire to save and protect your fern, overcorrecting so quickly can often lead to even worse issues for an already stressed fern.
Making these adjustments too quickly often leads to leaf drop or transplant shock so please consider implementing as much of a transition as you can when making lighting or placement corrections.
Sometimes you can care for your fern perfectly and the fronds of your fern still turn brown and crispy.
You assess and reassess the fern’s watering schedule. You smoothly transition the fern out of the indirect sun and give it more shade.
Yet still, its foliage is burned and so brittle that when you touch the leaves, pieces of it break off and leave a brown wiry leaf stalk that once was lush and green.
In situations like these, transplant shock is the likeliest culprit.
For example when you take your office fern home because you want to provide better conditions for it. Or in situations where your fern is too big for its pot, so you buy it a bigger one.
A plant that has a case of transplant shock, fern or otherwise, will experience a variety of telltale symptoms.
Entire branches of the plant can die, which is very distressing to witness. The indoor plant’s leaves will either fall off the plant or noticeably wilt.
Leaf scorch can also occur, but it’s not due to sunlight or heat this time. Leaf scorch often happens as a result of transplant shock.
What does leaf scorch look like in an indoor plant like the fern?
Your fern’s leaves can take on a bronze hue or a more golden color. This discoloration will be the most apparent along the leaf margins.
Sometime later, the golden areas will become brown and dry out.
If you suspect your fern has a case of transplant shock, leave the plant where it is. Maintain its watering schedule and cut back on the direct sun for now.
PRO TIP: Try diluting some table sugar with water and feeding the mixture to your fern. It may help pep it back up.
Pot Is Too Small
Ferns are not indoor plants that need frequent repotting. Every two years or so, you might want to upgrade the size of the plant’s pot.
I recommend an annual root inspection, as this will indicate when it’s time to expand your fern’s home.
During the root inspection, you’re looking for signs of the fern’s root ball becoming rootbound.
A rootbound plant is one that has outgrown its pot. The roots will encircle the perimeter of the pot over and over and can latch onto the pot.
You want to ideally move your fern to a new pot before that happens, as getting it out once it’s very rootbound is next to impossible.
Your fern becoming rootbound is not the only risk that can occur if it continues to grow in a pot that’s too small.
A small pot has less soil, which means the fern receives less hydration. The soil can dry out fast too, possibly before the root ball receives the water it needs.
Your poor fern is dried out even though you might be watering it as often as you should (which I’ll talk more about a little later in this guide, so check that out). The only solution is to upsize the pot.
How to Know What Size Pot to Use for Repotting Your Plant
To determine the new size of your fern’s pot, measure the diameter of its current pot. Then add two to four inches to that measurement.
Keep in mind that upgrading your fern to a new pot can induce transplant shock per the information above. In many cases, you can’t avoid transplant shock, but at least you know how to mitigate it now.
Overdoing It on Fertilizer
If you’ve ever grown an indoor plant and had it thrive due to its frequent fertilizer schedule, then you might assume you can catch lightning in a bottle and do it again.
The issue with that kind of thinking is that each indoor plant species has its own fertilizer requirements, including the fern.
Ferns generally grow between the spring and summer from April through September. You should fertilize the plant only monthly.
That makes the fern a rather light feeder, especially compared to some of the other plants in your indoor garden which may need fertilizer twice per month.
Remember though, your fern is not those plants, so don’t ascribe their care onto your fern.
The type of fertilizer you use for ferns is important
Ferns do best with a balanced fertilizer with an equal mix of nutrients (which will read 20-20-20 on the label).
When you overdo it on the fertilizer, your fern is overfed with nitrogen. Although nitrogen is a critical macronutrient that supports plant growth and coloration, too much can dry out and burn the tips of the fern’s foliage.
Once you see white crust on the surface of the fern’s soil, that’s a very obvious indicator that you need to scale back on the fertilizer application. That white crust is fertilizer residue.
For now, take your fern out of its pot, soak it to remove the salts and minerals, and repot it in fresh soil without any nutrients. Your fern should recover, but that’s not a guarantee.
As I promised, I want to talk about how your watering habits can contribute to the dried, crispy appearance of your fern.
Some fern species are drought-tolerant if they’re in shady conditions. After all, the lack of bright sunlight allows the fern to hold onto the hydration it has for longer.
In direct sun though, an underwatered or neglected fern will lose all its moisture to evaporation.
When you factor in high temperatures on top of that, it’s no wonder your fern looks like you feel when you spend too long on the beach without sunblock.
In the future, I’d suggest doing the fingertip test. All you have to do is plunk a finger into the fern’s soil and feel around. When moisture is sparse, water your plant.
Yes, following a watering plan is really that easy, and this is a much more reliable way of determining when your fern needs water than watering the plant every Tuesday and Thursday.
The last reason your fern is turning brown and crispy could be due to its humidity or lack of humidity.
Most people assume that humidity is heat, but that’s not quite right. Rather, humidity is moisture, and ferns love moisture.
You know how in the dry winter air, your skin dries out, your lips chap, and your hair feels like hay? That’s from too little humidity in the air.
Your fern will also dry out. The lack of moisture can cause yellowing and/or browning of its foliage.
How much humidity does a fern need? It can vary by species, but the humidity baseline is 50 to 70 percent.
Homes and offices contain about 50 percent relative humidity at most. Your fern thus may be happy with the humidity in these environments, but it could just as easily require more.
Since ferns are shade lovers, a bathroom is a great place to grow your fern. Be sure to move it into a sunnier room every now and again.
If you grow ferns at work and the bathroom is not a feasible location, then buy a mini humidifier and direct it towards your fern. After a few hours, its humidity should be much better.