If you are a fan of palm trees, you will be aware that – like any plant – they sometimes suffer from problems, and they can be quite vulnerable to disease and illness. This usually shows itself in the foliage of the palm. Let’s find out why do palm tree leaves can turn yellow.
Palm tree leaves turn yellow because the palm is missing some of the nutrients it needs to make chlorophyll properly. The chlorophyll is what makes the palm’s leaf bright green, but if the tree can’t make it, the leaf will turn yellow and look sickly. Yellowing leaves may also be due to age or infection, or sometimes water stress.
What Makes Palm Leaves Turn Yellow?
There are a number of things that can cause leaf yellowing for palm trees, and it’s important to work out what the exact cause is so that you can fix it.
There is no point in adding nutrients to the soil if the yellowing is caused by water stress, and likewise, you can’t fix a nutrient deficiency by treating the plant for fungal infection.
So, how do you know what is causing the leaf yellowing and how can you reverse it and restore your palm tree to its usual healthy green state? Palm trees should not have yellow leaves, so let’s look at the possible causes and their solutions.
Cause One: Water Stress
Water stress is a big cause of problems in all plants, and palms are no exception. It is very easy to kill a palm by over or under-watering it, and if you don’t pay attention to the soil conditions and how much your palm tree has to drink, this is quite likely to happen.
Palms have very shallow roots, so they cannot reach down deep to soak up water reserves in the cool of the ground. That means they need reasonably regular rainfall (or artificial watering by a human) if they are to survive. However, they are also plants that have adapted to dry, hot conditions, and they don’t want to be wet a lot of the time.
The root ball of your palm should not be sitting in water at any point. It should be damp around the roots, but not sodden or rotting. The soil needs to be damp right down to the bottom of the roots, rather than just on the surface.
It can be a challenge to water a palm tree well, but with practice, you will learn how to do it. Consider getting a water gauge so you can tell how dry (or wet) your palm’s soil is and correct any issues.
You should not need to worry too much about rainfall unless you live in a really wet part of the world. In general, this will just drain away into the ground, and won’t cause problems. However, heavy flooding and lots of standing water could kill even a healthy palm tree.
Cause Two: Nutrient Deficiencies
Like all plants, palm trees need the right nutrients in the right quantities, and if something goes wrong here, they are more likely to suffer from leaf yellowing because they won’t be able to produce chlorophyll and grow properly.
Nutrient deficiencies may result in yellow or orange or brown spots on the leaves, or bands of these colors. Palms require nitrogen, manganese, and magnesium in order to produce healthy leaf growth.
If you haven’t fed your tree for some time, consider giving it a dose of palm plant fertilizer, like this one above. It will contain these three macronutrients and should give your tree a boost if it’s suffering. You can use a soil testing kit to check the nutrient levels around your palm if you aren’t sure whether it needs more food.
Ideally, you should fertilize most palm trees three or four times a year, but make sure you check this information against your specific palm’s care recommendations, as different kinds of palms may have different requirements.
Cause Three: Movement Stress
If you have recently relocated your palm, either in a physical area or into a new container, it may show its stress at the move through leaf yellowing. As long as this is still accompanied by fresh, healthy green growth, you don’t need to worry too much.
As the plant adjusts and gets over the shock of being moved, it should drop these yellowed leaves (or you can remove them yourself with a sharp, sterilized tool if necessary) and replace them with more healthy growth.
Cause Four: Fungal Infections
Unfortunately, palm trees are somewhat vulnerable to fungal infections, especially when they are grown in humid environments. They like to be misted and they will enjoy it if you lightly spray them from time to time, but it’s important to also provide good airflow, or you may find that you are dealing with fungal infections.
You may be able to identify a fungal infection using a magnifying glass, and by looking at photographs of the different infections online. If your palm has got a fungal infection, you need to take action.
Fungi like damp, warm conditions, so you should take steps to change the environment. Only water your palm when it has dried out. Provide a light but constant airflow that will dry out the fungi. Keep your palm away from other plants so the air around it keeps moving and it can’t affect others.
You can couple this with fungicide treatments, such as a copper fungicide option. Remove affected growth and keep trying to gently dry your palm without letting it die of thirst. The drier it is, the less the fungi will thrive.
Cause Five: Insect Attack
Palm trees also suffer from a range of pests, and if they are being attacked by a lot of insects, they may start to struggle. Their leaves will turn yellow as a result of stress.
You can look for insect infestations on your palm using a magnifying glass. Things like palm aphids (small black and white rounded insects) will attack the leaves, sucking sap from the veins.
Mealybugs and scale insects – which you may be familiar with if you have other kinds of houseplants – are also common palm predators. Mealybugs are small and look like little cottony balls. They can get into the roots of the palm, and they like to eat the palm’s buds as well. They prefer warm, damp environments.
Scale insects are small, brown circles that will also attach themselves to the undersides of the palm’s leaves and drink the sap. They can be hard to spot, as they just look like little blemishes on the leaf.
Spider mites are another common palm pest, and these are very hard to spot. They will leave tiny threads all over the leaves, which are often easier to see than the insects themselves.
There are many other kinds of insects, too, but these are the common pests you might see on indoor palm trees. If possible, quarantine a sick palm tree so that it cannot spread its unwelcome guests to other plants.
Outdoor palm trees are even more vulnerable to being infected by insects from wild palm trees, which can totally ruin your palm and may even kill it.
You may need to seek expert advice for the pests that attack large outdoor palms, as these can be serious. For indoor palms, some of the common treatments that you might use on any infected houseplant should work.
Use rubbing alcohol on scale insects, and soap and water sprays on other kinds of insects. Repeat the process multiple times to ensure that the infestation has actually been dealt with, and keep your plant isolated in the meantime to prevent the insects from spreading.
Cause Six: Age
A few yellow leaves on a healthy palm tree can safely be ignored because as the leaves age and the palm gets ready to shed them, they will turn yellow or brown. They should then drop off, and end up being replaced by healthy greenery.
All plants need to shed foliage that they have finished with, and palms are no exception. One or two yellow leaves that are soon discarded are nothing to worry about. You should only be concerned if the palm tree’s leaves seem to be turning increasingly yellow, or if the foliage is not being dropped.
If this happens, look to the other causes and see if you can pinpoint an issue. You may need to get a specialist to look at your palm if it seems to be getting seriously sick.
Palm tree leaves can turn yellow for a whole variety of reasons, and there is no single cause that is the most common. If you have recently relocated your palm, it may be stressed from the move. You might be over-watering it, or it might be suffering from an infestation by fungus or insects.
Keep an eye on any leaf yellowing, because it usually shows that something is wrong with the palm tree, and you may need to fertilize, treat for pests, or change your watering routine. Hopefully, as long as you take swift action, your palm will soon be back to full health!