Why Is My Asparagus Fern Turning Brown? (And How to Fix It)


Potted Asparagus Fern Turning Brown.

The beautifully green and dainty Asparagus Fern is an attractive addition to any home.

But what about when your vibrant, fresh plant starts to turn crispy and brown? When this happens, it can be hard to know how to care for your Asparagus Fern to get it back to full health.

Read on to find out how to keep your Asparagus Fern looking bright and strong.

The most common reason for an Asparagus Fern turning brown is a lack of humidity. Asparagus Ferns love humidity and need to be misted with water daily. Other causes for it turning brown include sunburn, too much heat, and nutrient deficiency.

There are several reasons why an Asparagus Fern may turn brown, but they are a hardy plant and relatively easy to revive once you identify the problem.

Causes of Asparagus Fern Turning Brown

When your plant starts to look dry and brown, it’s not always easy to know what steps to take to revive it.

Fortunately, below you will find a comprehensive guide of the reasons Asparagus Ferns turn brown and how to combat each problem.

Lack of Humidity

Asparagus Ferns are native to rainforests. This means that they are used to living in very humid environments.

It’s common for ferns placed indoors to lack humidity. The air inside is often much drier than outside. Heating and air conditioning can also increase dryness.

If it isn’t humid enough, your Asparagus Fern will start to show signs of drying out and turn brown. You may even find that its needles start to drop.

How to Fix

The easiest way to create a more humid environment for your Asparagus Fern is to spray it with a light misting of water daily.

Be careful not to place your fern too close to air conditioning units or heaters, as the air will have the lowest humidity there.

Additionally, you might consider standing your plant in a gravel tray to increase humidity:

  1. Add a thin layer of gravel to a large tray.
  2. Put your Asparagus Fern in its pot on top of the tray.
  3. Keep the gravel moist (but not wet).

When the water evaporates the humidity in the air around your plant will increase.

Overwatering

An overwatered Asparagus Fern is not a pretty sight. The leaves will turn yellow and brown, sometimes to the point where there is hardly any green.

It’s quite easy to overwater an Asparagus Fern because it is accustomed to drought. Ideally, the top two inches of soil should be dry to the touch before watering your fern.

Asparagus Ferns have thick roots which retain water well. As a result, if the soil is too wet the roots will rot. This will cause brown leaves because they are not getting the necessary nutrients delivered to them.

How to Fix

An overwatered fern is generally easy to fix. Firstly, don’t water your Asparagus Fern again until you’ve checked a few things:

  • Are the top two inches of soil dry? Make sure the soil is dry to the touch before watering.
  • Test how humid the air is. If the plant is receiving moisture from the humid air (which it loves), it will not require as much moisture from the soil.

As a general rule, water your Asparagus Fern once or twice a week. Be sure to mist your plant daily so that it is receiving moisture in the right places and not solely in the roots.

Underwatering

Asparagus Ferns retain a lot of their water in their thick roots, but if this store diminishes, they will suffer.

An indication of underwatering is drooping, brown/yellow leaves which have turned spindly and may even drop off.

Although Asparagus Ferns are used to drought conditions, it is still possible to underwater them.

A lack of water will result in browning because there is not enough water to carry the necessary nutrients to all areas of the plant.

How to Fix

The dryness of the soil is a good indication as to whether you have been underwatering your plant.

To have about two inches of dry soil below the surface is optimum and the perfect indication that you should water your Asparagus Fern.

Soil any dryer than this is evidence that you are underwatering your plant.

Keep humidity levels high to help stop your fern drying out, and make sure to water more frequently during hot temperatures. You should be watering your fern 1-2 times per week.

Too Much Heat

So, we’ve already established that Asparagus Ferns are no strangers to hot and humid conditions in their natural habitat. But is there such a thing as too much heat?

Unfortunately, yes. If your fern gets too hot it is prone to drying out. A dried-out fern is a sorry sight, with scorched, crispy, brown leaves.

The ideal temperature for an Asparagus Fern is between 60 – 70°F (15.5 – 21°C). Any hotter than this and the soil may struggle to retain its moisture.

Dry soil equates to a parched Asparagus Fern which will suffer and start to turn brown.

How to Fix

If temperatures are above 70°F (21°C), consider moving your Asparagus Fern to a cooler room. Use a thermometer to see which area of the house is the best for your plant.

In warmer temperatures be sure to keep an eye on the soil, you may have to water more frequently if the water is evaporating very quickly.

Opening windows in the mornings and evenings, and keeping them closed during the hottest part of the day, can help keep things cooler.

Sunburn

Asparagus Ferns grow on the rainforest floor – a shaded and damp location. Direct sunlight doesn’t often find its way through the lofty tree-boughs to the floor below.

As a result, Asparagus Ferns aren’t very well adapted to sitting directly in the sun. They much prefer a shadier spot which better represents the conditions of a tropical rainforest.

If you notice that the leaves of your plant are starting to look scorched and turning yellow or brown, it may be that your Asparagus Fern has had a bit too much sun.

The sun directly dries out the leaves, whilst also drying out the soil as well. This means that sunburn will cause double damage to your fern, attacking the leaves whilst also dehydrating the plant.

This will lead to a dry plant which has visibly turned crispy and yellow or brown.

How to Fix

First, determine if sunburn is the cause of the browning. Are any of the following statements applicable to your plant?

  • It is sitting on a window-ledge or somewhere that receives direct sunlight.
  • The damage is most visible on one side of your fern, the side where sunlight hits it.
  • It sits in direct sunlight for more than two hours per day.
  • You recently moved your plant nearer to a window and are now noticing this problem.

If any of the above statements apply to your plant, it is very probably that your Asparagus Fern is suffering from sunburn.

To fix the problem, consider moving your plant to a shadier area in your house.

If you are still concerned about the amount of direct sunlight it is receiving, there are covers such as ‘window films’ which can block the number of UV rays that can get through windows.

The ideal growing condition for your Asparagus Fern is a combination of indirect light and partial shade.

These conditions can be achieved in a room that is well lit for part of the day. Once out of the direct sun, no further leaves should change color.

Pest Infestation

There are a few pests which are particularly fond of the Asparagus Fern. These include Spider Mites, Scale Insects, and Mealybugs.

One of the biggest problems with pests is that they feed off the plant and rob it of its nutrients.

Your Asparagus Fern will be working hard to draw in water and nutrients from the soil, but the pests will be reaping the rewards!

In addition, pests cause damage to the plant by eating its leaves and Mealybugs will also leave behind a sticky substance which can encourage mold growth.

An indication of the presence of insects are the appearance of white webbing on the leaves and branches, or lumps and spots appearing on the leaves.

If your Asparagus Fern is struggling with a pest infestation, its leaves will likely turn brown.

This happens because the little critters feed on the plant, stealing its nutrients and weakening it.

How to Fix

You have two main options when trying to combat a pest infestation on your Asparagus Fern. You may find that you have to try a combination of both.

  1. If the infestation is not out of control, consider treating your Asparagus Fern with an insecticide. Bear in mind the following factors:
  • Asparagus Ferns do not respond well to pesticides – be sure to check that you are using an insecticide.
  • The best tactic is to use insecticidal soap to treat the infestation.
  • Insecticidal soap needs to come into direct contact with the pests.
  • Spray treatment on plants in the morning or in the evening when temperatures are at their coolest. This will avoid it evaporating before it has time to work!
  • If you find yourself confronted with a more severe infestation or one which does not seem to have been curbed by insecticidal soap, you should prune the infected leaves/branches from your plant. You may have to cut the whole plant down the soil line.

Diseases

Brown spots on Asparagus Fern leaves.

The biggest challenge that your Asparagus Fern will face, in terms of diseases, is fungus. There are several types of fungi that affect Asparagus Ferns and they impact different parts of the plant.

Crown rot is caused by one type of fungus and often lives in the soil.

It infects the Asparagus plant through the roots and damages them so that they are unable to carry nutrients to the stem and leaves. Affected ferns will wilt and turn brown.

Asparagus rust is caused by a fungus and makes orange and brown spots appear on the leaves and stem of an Asparagus Fern.

These patches spread and grow and cause the fern to have a brown appearance.

How to Fix

Crown rot is best caught early, try pruning the plant and moving it to new soil. Make sure to dispose of the old soil away from other plants as the fungus may infect them too.

Fungicides don’t work on this type of fungus and it may cause irreversible damage to the fern.

You can treat asparagus rust by pruning the infected parts of the plant and using a fungicide. These treatments should result in your Asparagus Fern returning to full health!

Inadequate Light

Whilst Asparagus Ferns may not appreciate direct sunlight, they also don’t want to be left in the dark!

Your plant can survive in a shadier spot, but the best choice for your fern is to give it the opportunity to experience some sun.

All plants need sunlight to allow them to carry out the process of photosynthesis.

This process allows them to turn their ingested nutrients into food and, in turn, keeps their leaves green.

Without enough sunlight your fern isn’t able to make sufficient food for itself. You may notice that your fern isn’t growing very well and that its leaves and branches are turning yellow and brown.

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How to Fix

The best thing you can do for your fern is to find it a spot where it’s getting a good amount of natural sunlight. Just be careful that it isn’t receiving too much direct sun.

Rooms with windows which face east, west, or north are ideal for letting in enough light for your plant.

If you don’t have access to a room with sufficient natural light, you can always substitute sunlight using a specifically designed plant light.

These grow lights recreate the properties of sunlight, making them a great option to ensure your Asparagus Fern is getting everything it needs.

Nutrient Deficiency

Asparagus Ferns thrive in rich soil. In their natural habitat on the rainforest floor, they would receive a lot of nutrients from the surrounding decomposing organic matter.

Therefore, it is easy for an Asparagus Fern to have a nutrient deficiency when planted in a pot indoors, but there are ways to combat this problem!

Your fern likes to have an equal balance of potassium, nitrogen, and phosphorous in its soil.

If your plant is suffering from a nutrient deficiency you will notice that the leaves are starting to look unhealthy and turning yellow or brown.

Browning of the leaves occurs because the main body of the plant has to use the available nutrients, and there are none left over to feed the rest of the fern.

How to Fix

  1. Use a DIY kit to test the nutrient levels and PH of the soil
  2. If you find that the soil is lacking in potassium, nitrogen, or phosphorus, or that it has a PH level which is not between 6.5 and 7.5, your plant likely has a nutrient deficiency.
    • Having the wrong PH levels will affect the plants’ ability to absorb nutrients.
  3. To combat a nutrient deficiency feed liquid fertilizer, or water-soluble fertilizer, to your Asparagus Fern. Dilute it to half strength. Feed your plant every 1 to 2 weeks.
    • If you need to alter the PH levels use lime to make the soil less acidic, and peat moss to increase acidity.

Overfertilization and Salt Build-Up

It can be easy to think that fertilizing your plant can only do good. Unfortunately, too much fertilizer can cause salt build-up in the soil and cause damage to your plant.

Too much salt in the soil can cause plants to dry out. This is because the salt absorbs a lot of moisture instead of the plant.

Particles from the salt can also be carried up to the plant via the roots and the toxic substance will build up in the leaves.

An Asparagus Fern which is suffering from overfertilization will appear wilted and brown with dry leaves. Dryness is caused by the toxic build-up in the leaves as well as the salt in the soil robbing the plant of its moisture.

How to Fix

Focus on leaching the salt from the soil of your plant:

  • Make sure the plant pot has big enough holes in the bottom to allow for proper drainage when watering.
  • Leach your soil by running water through it, this will wash the salt out.
  • Put your plant somewhere which will help the soil dry out after this process.

In general, you should pay attention to how much fertilizer you have been feeding your Asparagus Fern.

Asparagus Ferns favor liquid fertilizer and it should be diluted to half strength. One application every 1-2 weeks is sufficient.

Cold Drafts

The Ideal temperature for your fern is between 60 – 70°F (15.5 – 21°C). Generally, this makes them a great house plant as this is a common temperature for inside the home.

However, your Asparagus Fern will struggle if temperatures drop below 60°F on a regular basis.

Asparagus Ferns also appreciate a still environment without much movement. This means that another factor which will disturb their growth is a draft.

So, there are two main things which you should avoid exposing your Asparagus Fern to: cold temperatures and cool drafts.

Bear in mind that it’s not only a problem if the air outside is cold, such as in winter, but also if you use air conditioning or fans.

Cold temperatures and drafts can affect the plants ability to take nutrients from the soil. If the roots are too cold, they won’t be able to work effectively.

If roots are unable to carry out their task of carrying nutrients up from the soil to the plant, your Asparagus Fern will suffer.

Ineffective functioning will lead to brown and dead looking leaves and branches.

How to Fix

Have a look at where your Asparagus Fern is placed. If there is a nearby window or a door, or even an air conditioning unit or fan, there is a chance that your Asparagus Fern is sitting in a draft.

Move your fern away from anywhere with a lot of airflow, such as drafty corridors or windowsills and be careful not to use air conditioning and fans around your Asparagus Fern.

You could consider blocking drafts by using a draft excluder or caulk to seal up gaps which let air in.

Similarly, keep an eye on the temperature of the room and, if necessary, move your Asparagus Fern to a warmer one.

Conclusion

If you notice your Asparagus Fern turning brown it is likely that there is an easy fix to the problem.

You’ll soon find that your feathery fern is back in no time, brightening up your house with its pleasant greenery.

Have you had any problems with your Asparagus Fern? What did you do to solve the issue?

Arifur Rahman

I'm the owner of gardenforindoor.com. After completing my bachelor of science in agriculture, I'm serving as a civil service officer at the Department of Agricultural Extension, Bangladesh. I started Garden For Indoor to make your indoor gardening journey easy and enjoyable.

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