Asparagus ferns will turn yellow if they are experiencing any kind of environmental stress. The best way to approach this situation is to figure out the cause of the discoloration so that you can quickly remedy it.
The most common causes of yellowing asparagus fern are overwatering, underwatering, too much light, insufficient light, incorrect fertilizing, transplant stress and pests.
In this article, we will discuss the different causes of yellowing asparagus ferns and how to remedy each.
Why is My Asparagus Fern Turning Yellow?
The plant is overwatered
Overwatering is the most common cause of yellowing asparagus ferns. This is because the waterlogged soil can cause damage to the roots which can eventually result in leaf damage.
It can be easy to make the mistake of overwatering if you plant the fern in a pot that has no drainage holes, or if the soil you are using does not drain the water well.
You can also overwater the plant if you keep it indoors or in low light, even if you are watering it only moderately. The water in this case is unable to evaporate as quickly as necessary, causing the same problems as in any other case of overwatering.
Overwatering causes yellowing leaves because the roots are not able to take up oxygen, as they are constantly in boggy soil. The soil needs time to be dry enough for air to flow through the spaces in the soil, so that the roots have access to the oxygen they need. When its ability to effectively transport nutrients is impaired, the plant cannot get what it needs to survive.
You can tell whether your asparagus fern is overwatered by checking the soil to see how much moisture it retains after watering. If it takes the water a long time to drain after watering, you might need to change the soil. You can make your own soil mix by mixing one part compost with three parts perlite and six parts peat.
You should also check the pot you are using. The pot should not be too big for the plant, because a big pot needs more soil to fill it, and more soil means it will take a longer time to dry out between watering. The pot also needs to have drainage holes at the bottom so any excess water can flow out instead of adding unneeded moisture.
Using terracotta or clay pots is also helpful to prevent overwatering. These materials are more porous, allowing air and water to travel more easily through them compared with plastic or steel pots.
You can remedy an overwatered plant by reducing the frequency of watering to allow the plant to dry out more. If the plant does better by just lessening the watering frequency, that should be enough. If the plant has been overwatered for so long that root rot has set in, it will be much harder to remedy. You can try to save the plant by removing it from the soil to check the roots. If there are parts of the roots that are brown or black, remove them using sterile scissors.
The plant is underwatered
Even though asparagus ferns look high-maintenance, they are actually quite hardy. These plants are drought-resistant because of their tuberous roots that store water for times when there is little to no rainfall.
Despite asparagus ferns doing well despite long periods without water, this does not mean they should be constantly deprived of water. A lack of water can cause the plant’s leaves to turn yellow and then brown. The first signs can be seen on the leaf tips and peripheral foliage, but it will affect the rest of the leaf over time. They will feel dry and crispy to the touch.
This issue is much easier to identify, because the soil will look and feel bone dry. You should also think of the last time you watered your plant.
You can fix this by simply resuming the correct watering schedule for your plant. Underwatering is easier to correct compared to overwatering and soon enough, new foliage will grow to replace the leaves that dried up. You can also remove the dried parts of the plant to retain its aesthetic appeal.
Note that there are also other factors that can increase the likelihood of underwatering. These include high temperatures in the plant’s environment, low humidity, and if the plant is pot bound.
Too much light
Excessive light can cause the leaves of your asparagus fern to yellow due to scorching. These plants can only tolerate sunlight for one to two hours a day, which is why they much prefer being kept in indirect light. Keeping the plant in a north or east-facing window should do the trick. Be sure not to keep the plant too close to a window that gets a lot of light, especially during the summer.
Not enough light
Another common cause of yellowing asparagus fern leaves is low light. This problem may be hard to identify in its early stages because the signs develop slowly. You might notice the plant stretching, known as etiolation, because it is growing in the direction of the nearest light source out of desperation.
Plants need light for photosynthesis to make their food. So, if there is insufficient light, the plant will not be healthy, and its leaves will turn yellow.
Fortunately, this problem is easily fixable. Place the plant in a location that is able to provide the plant with the little light it does need for the day. They like bright, indirect light such as near a window, but not directly under the sunlight that flows in.
You can check whether the plant is getting sufficient light by holding up your hand: If the shadow cast on the wall is clear, the light is sufficient. If the shadow cast is faint and indistinct, the light in that spot is not enough for your plant.
You can help a plant that has not been getting enough light by moving it into a spot that does have the correct light. This is a bit tricky since light can change depending on the seasons, so make sure you check the location of the plant every couple of months.
Fertilizer problems
Your asparagus fern will do well if it gets a steady supply of nutrients, but be wary of over fertilizing. You can dilute your fertilizer to half strength if you are afraid you are going to give too much.
A plant that does not get fertilized enough will also develop yellow or brown leaves.
You can counteract overfertilizing by thoroughly flushing out the soil with water. Run water through the soil for several minutes so that the excess fertilizer salts dissolve and wash out of the soil. Do not fertilize your plant again for a few months.
Transplant stress
When you buy your new asparagus fern, it probably came from a nursery with a greenhouse that provided it with ideal conditions. The conditions in your home are not as perfect as those in the nursery, so your new plant will need time to adjust. The leaves on your plant will turn yellow or brown in the first few weeks.
There really is not much you can do about a plant going through transplant stress. You just need to provide conditions for your plant that are as close to ideal as possible, and the plant will acclimatize over time.
Pests
The most common pests to attack asparagus ferns are scale insects, mealybugs and spider mites. In particularly bad infestations, the leaves will turn yellow because of the pests sucking out their sap. They pierce the leaves to steal water and resources, and thereby weaken the plant.
You can prevent the plant from infestation by regularly checking the asparagus fern for these insects. Isolate any new plants you have for at least a week before placing them near your other plants. Observe the new plant for any signs of bugs and get rid of them while keeping your other plants safe.
Conclusion
Asparagus ferns turn yellow when they are experiencing some kind of environmental stress. Being able to correctly identify the cause of the stress is important if you want to fix the plant.
The most common causes of yellowing asparagus ferns are overwatering, underwatering, too much light, insufficient light, fertilizer problems, transplant stress and pests.
Asparagus ferns are hardy plants, so as long as you provide them with their basic needs, you will have no problem growing them successfully.
Image: istockphoto.com / Nahhan