Asparagus fern is a common name used for several different species of plants belonging to the Asparagus genus. Even though they are different species, they share many of the same characteristics, such as their delicate, green, feather-like foliage that can make a living space feel as though it is in the middle of a forest.
Contrary to its name, the asparagus fern is not actually a fern but a perennial plant that is more closely related to the asparagus that we eat.
In their natural habitat, in South Africa, asparagus ferns are low-growing, spreading plants, but as they have grown in popularity worldwide, most people choose to plant them in hanging containers and let their foliage spill over the edges.
As with all houseplants, asparagus ferns suffer their share of problems, a common one being browning foliage. If your asparagus is turning brown, the most likely causes of the discoloration are underwatering, overwatering, low humidity, insufficient light, excessive light, temperature changes, or natural aging.
In this article, we will discuss the different causes of a browning asparagus plant, and what you can do to fix the problem.
Why is my asparagus fern turning brown?
Underwatering
The asparagus fern is tolerant of the occasional underwatering, but if you neglect to water it constantly, it can cause the plant to turn brown.
If it does not get the water it needs to survive, your asparagus fern will not only lose moisture from its cells; it will also become nutrient deficient. Plants need water to transport essential nutrients from the soil into their roots and throughout the rest of the plant. Thus, both the dehydration and the lack of nutrients will contribute to the weakening and browning of the plant’s foliage. If the issue is not resolved in time, the affected foliage will fall off and the plant may even die.
If you think that your asparagus fern has been underwatered, first confirm your suspicions before taking any measures to save the plant. Touch the top two inches of soil in the pot to feel if they are dry. If the soil is bone dry and crumbly, the plant is most likely dehydrated.
To fix your underwatered asparagus fern, it is best to water it from the bottom. Place the pot in a shallow basin filled with three inches of tepid water and leave it there for 10 to 15 minutes. The thirsty soil and roots will absorb the water through the drainage holes at the bottom of the pot.
After 10 to 15 minutes, remove the pot from the basin and place it on a drying rack to allow the excess water to drain before placing the plant back in its usual spot.
Although it may be tempting, do not overcompensate for your underwatering. The plant is better off being eased back to full rehydration than overly soaked with water from the outset. Remember that the roots are probably weak and stressed from being deprived of water for so long, so the last thing they need is to be overwhelmed with a deluge.
For seven days, give the plant a little water, gradually increasing the volume each day. After the seventh day, the soil should be appropriately moist and you can then return to your regular watering schedule.
The best way to avoid underwatering in the future is to check the soil regularly. If the top two inches of soil are dry, that is your cue to water the plant; if the soil is still damp, wait one or two days before checking it again.
Overwatering
While underwatering is bad for your asparagus fern, overwatering can have even more damaging consequences, starting with browning foliage.
When the plant’s soil is constantly waterlogged, the roots will never get to dry out between waterings. This means they will not have access to oxygen, which is as vital to them as it is to us, and they will eventually drown. It goes without saying that dead roots will not absorb water and nutrients from the soil, with dire repercussions for the entire plant.
Once the roots are dead and decomposing from root rot, the foliage will follow by turning brown and drooping.
If you manage to catch the overwatering in its early stages, all you will need to do is to stop watering the plant and place it somewhere sunny, with good airflow. The heat from the sunlight and the air circulation will help dry out the soil in the pot as fast as possible.
If you suspect the plant has already developed root rot, you will need to unpot it and wash the soil from its roots to inspect them. Do this gently, so as not to do any more damage to the already fragile roots.
Inspect all of the roots closely, looking for sections that have turned brown or black. These roots are rotten; remove them using a sterile pair of scissors, until only the healthy, white roots remain. If there is any brown foliage, remove that, too.
Let the plant’s roots air-dry on a flat surface for a few hours after pruning them. Once they have dried, choose a new pot with drainage holes and fill it halfway with fresh, well-draining potting mix. Place the plant in the middle of the pot and cover the roots completely with more soil.
Do not water the plant immediately after repotting it; wait a week to give the roots enough time to recover from the trauma of repotting.
Avoid overwatering your asparagus fern in the future by knowing when it actually needs to be watered. Using the same method as to avoid underwatering, touch the top two inches of soil in the pot to check whether they are dry before you water your plant. If the soil is still a bit damp, wait one or two days before checking the moisture level again.
Low humidity
If you keep your asparagus fern indoors, the air may be a bit too dry for it. This can cause its foliage to dry out faster than it should, resulting in browning.
The dry indoor air is usually due to air-conditioning or central heating. If the plant is exposed to this low humidity for a prolonged period, its needles will start to fall off.
To give your plant a little more humidity, you can mist the foliage with water from a spray bottle a few times a week. This will help alleviate the dryness of its foliage. Mist it in the early morning, so that the water droplets have time to dry out over the course of the day. If you mist it at night, the foliage might remain wet until morning, which increases the chances of fungal growth and rotting.
Another method you can try is to place the plant’s pot on a tray filled with pebbles and water. As the water evaporates from the tray, it will moisten the air around it.
You can also keep your plant in the kitchen or the bathroom, as these are the most humid rooms in your house.
If you have other humidity-loving plants, place the asparagus fern close to them so that together they can create a microclimate around each other.
Finally, if you have the means, you can purchase a humidifier to automatically regulate the humidity in the room where the plant is kept.
Insufficient light
If your asparagus fern is kept in low light conditions, this can also cause it to turn brown.
Plants need light in order to photosynthesize – the process by which they create their own food and energy. Photosynthesis also allows plants to create more chlorophyll, which is the pigment that gives plants their green color.
So, if your asparagus fern is too far away from a window or other light source, it will start to become paler in color, weaken, and develop stunted growth. Eventually, its foliage will droop and turn brown from the lack of necessary resources.
If your asparagus fern is turning brown because of insufficient light, you can fix the problem by moving the plant closer to a light source. Ideally, place it near a north- or east-facing window, because these let in bright, gentle light in the morning, while being in the shade for the afternoon.
If you live in a place where sunlight is scarce in the winter time, you can use a grow light as an alternative until spring arrives and the sunlight is sufficient again.
Excessive light
The asparagus fern needs bright, indirect light, and direct sunlight can scorch its foliage and turn it brown. The intense light and heat of full sun will dry out the foliage in a matter of hours, especially during the summer. If you do not resolve this problem in time, the plant’s needles will start to fall out.
If you suspect that overexposure to sunlight is the reason your asparagus fern is turning brown, move it to a shadier spot immediately. If it is outdoors, move it under a large tree so it is only exposed to the dappled sunlight that filters through the tree’s branches.
If you keep the plant indoors, move it a little further away from the closest window, or try hanging a sheer curtain over the window to diffuse the light’s intensity.
You can cut off the burnt foliage with sterile scissors if you find it aesthetically unappealing. Otherwise, just wait for it to fall off over time.
Usually, a sun damaged plant will also be dehydrated, because the sun’s heat will dry out the soil very quickly, too. Check the moisture in your plant’s soil and water it if needed, as you would an underwatered asparagus fern.
Temperature changes
The asparagus fern is native to South Africa, so it likes its temperature fairly warm – ideally between 55 and 70 degrees Fahrenheit. If you expose it to temperatures lower than 55 degrees for extended periods of time, either by leaving it out in the winter cold, placing it under an air-conditioning vent, or keeping it near a drafty door or window, the low temperature will stress and shock the plant and its foliage will turn brown.
Being in a cold room also makes the soil dry out more slowly, which can increase the risk of overwatering and root rot.
If you think that temperature changes are causing the browning of your asparagus fern, try using a thermometer to monitor the temperature in the room where you keep your plant. Keep it away from air-conditioning vents and drafty doors and windows, and if you keep it outdoors, make sure to bring it in before the frost starts.
Natural aging
If you have ruled out all of the other possible reasons for your asparagus fern turning brown, it might simply be the plant’s natural aging process.
Like all plants, the asparagus fern sheds its old foliage to make room for new growth. It has limited resources, so it will naturally get rid of its older foliage to focus its energy on growing new leaves.
You can tell when the browning is due to natural aging, because it will be the leaves nearest the base of the plant that are turning brown. Often the browning happens just one leaf at a time, as opposed to all the other causes, where almost all of the foliage turns brown at the same time.
There is nothing you need to do in this situation, since the plant is probably completely healthy. If the brown foliage bothers you and you cannot wait for it to fall off on its own, you can always prune it off with sterile scissors.
Conclusion
The asparagus fern is a perennial plant native to South Africa that has extremely delicate, feather-like foliage. It is actually not a fern at all, despite its name, and is more closely related to edible asparagus than to ferns.
When grown indoors, this plant gives your living space the feel of a forest. It is often grown in hanging containers, because its branches spill so beautifully over the edges.
As with all plants, however, the asparagus fern is prone to certain problems, one of which is browning foliage. The possible causes of this are underwatering, overwatering, low humidity, insufficient light, excessive light, temperature changes, and natural aging.
Once you have established exactly which of these is causing your asparagus fern to turn brown, you will be able to take the correct measure to restore it to health as soon as possible.
Image: istockphoto.com / GOLFX