We had a couple of citrus trees lose their leaves. First, our lime tree after it was heavily pruned, and then our potted Meyer lemon tree after going through a cold winter. In both cases, the leaves grew back, but that prompted the question–what are some other reasons why citrus trees lose their leaves? We did some research to find out. Here’s what we found.
Citrus trees tend to drop some leaves when the tree is blossoming and forming fruits. However, if leaf loss is significant, it’s usually a sign that there’s a problem, such as nutrient deficiency, root rot, extreme temperatures, and overly dry soil. Leaf loss can be reversed if the issue is resolved quickly.
In this article, we’ll cover more details about the problems causing leaf loss in citrus trees. We’ll also give you some tips we’ve learned about how to keep your citrus trees from losing more leaves. Let’s get into it.
Do Citrus Trees Lose Their Leaves in Fall or Winter?
It’s not normal for citrus trees to lose leaves in the fall or winter. If they do, it’s likely from frost damage. Citrus trees are evergreen and not deciduous trees–which shed their leaves every year during the fall and winter seasons. If many leaves are dropping, check if frost or another issue could be causing it.
Citrus trees generally don’t like cold and freezing temperatures, which of course naturally occur in the fall and winter. Frost damage happens when your citrus tree is exposed to a temperature of 28ºF (-2ºC) or below for at least four hours. Lemon trees normally aren’t as cold-resistant, which is why they’re often grafted onto orange tree rootstocks.
Light frost doesn’t usually cause severe damage to a citrus tree, however young and tender trees, along with new growth can be affected.
Hard frost freezes the water content in the trees’ cells, which causes damage and dehydration to the walls of these plant cells. When the sun comes up, cold injury is likely to occur as the water in the cells defrosts too fast, killing the stems and leaves and stems.
If you have potted citrus, consider moving them indoors for the winter. If you have planted citrus trees, consider covering them with sheets, cardboard, or other insulating materials.
Planting them on the southern end of your property can provide them with more sunlight in the winter. Additionally, planting alongside a southern facing wall is beneficial as it can hold heat for most of the day and reflect it on the tree.
Why Do Citrus Leaves Turn Yellow and Fall Off?
Citrus trees like orange, lime, lemon, and grapefruit are evergreen, which means they don’t lose their leaves in the fall as many trees do. For example, apricot trees are deciduous, so it’s normal for them to lose their leaves in the fall. So, what does it mean if your citrus tree starts losing its leaves?
Citrus trees’ leaves can turn yellow and fall off due to poor nutrients, pests, disease, extreme temperatures, over or under-watering, and anything else that could stress the tree. The best way to reverse yellow leaf drop is to identify the issue and fix it as soon as possible.
If your citrus tree drops a lot of leaves, this indicates that there is something wrong with your plant. It could be because of extreme heat and wind, temperature fluctuation, overly dry soil, a nutrient deficiency, pest infestation, or root rot due to fungal infection or overwatering. Leaves typically turn yellow before they fall.
Leaf drop and yellowing are two of the most common problems for orange, lemon, and lime trees. It’s vital to determine the exact cause so you could save your tree before it loses all of its foliage and dies.
Let’s take a closer look at some of the reasons why citrus trees’ leaves turn yellow and what we can do about it.
If your citrus tree is dropping more leaves than necessary, it could be a symptom of root rot. Root rot is usually caused by overwatering, which creates an environment for a fungal infection to develop in the roots.
For example, the Phytophthora fungus causes root rot by invading the root system. The fungus can be found in the soil or the tree’s trunk and thrives in a wet and moist environment. When the infection has taken hold, it can result in citrus leaves turning yellow and eventually dropping.
Overwatering can easily occur when your citrus tree has poor drainage. For this reason, potted citrus trees are the easiest to overwater as they’re notorious for not having great drainage. If your potted citrus tree has water that’s sitting for too long, and root rot begins to take hold, repotting your citrus tree with fresh soil is likely the best bet.
Because drainage is so important, make sure your pot or the area where you plant your tree has good drainage and that you’re using well-draining soil. A great way you can improve a planted citrus tree’s drainage is by providing it with a slight elevation, like on a small hill, or by planting it in a raised garden bed.
Minimizing irrigation is also recommended. You can do this by mulching to improve water retention and deep watering to train the tree to hold more water. Straw, leaves, and other organic materials or clipping work great as a mulch and can also provide a slow-release of nutrients in the soil.
Fluctuation in Temperature
Another common cause for leaves yellowing and dropping is temperature fluctuation. Citrus trees love warm weather, but they prefer it mild. If it’s too hot or cold, the trees can become stressed and start to shed leaves to protect the rest of the tree. Generally, citrus trees prefer temperatures above 30ºF and below 90ºF. Keep in mind that wind chill is also a factor for determining the temperature of citrus trees.
While they can tolerate colder or hotter temperatures for a time, potted citrus should be moved indoors and planted citrus should be shaded or insulated if possible.
If your citrus tree suffers from extreme temperatures, leaf drop would start slowly but would continue turning yellow and falling off until the tree can handle the conditions better.
The lack or loss of essential nutrients from the soil and the citrus tree can also cause leaves to yellow and drop. Additionally, it can slow or prevent flower and fruit production. These vital nutrients include nitrogen, iron, magnesium, zinc, and manganese.
The best way to supplement your citrus trees is with a high nitrogen fertilizer. The nitrogen should be twice as much as phosphorus and potassium (these three nutrients make up the “NPK” you see on store-bought fertilizers). For example, Down to Earth’s organic citrus fertilizer has an NPK of 6-3-3.
The amount of fertilizer to use depends on the size of your tree and the type of fertilizer you buy. Fortunately, most store-bought fertilizers provide calculations on the back of the package. Remember that potted citrus trees need less fertilizer since they have a finite amount of soil to work with.
Be careful about overfeeding your citrus trees as a high concentration of nutrients (and especially nitrogen) can burn the roots and cause leaf drop, slowly killing the tree.
For more about store-bought fertilizers for your potted citrus tree, I put together a guide that covers the best two that you can buy. Both brands have worked extremely well for our citrus trees, so check out the post if you’re interested.
If you’d like a safer and more natural method of fertilizing, consider adding 1-2 inches of compost on top of the soil (under the mulch if you’re mulching) 1-2 times per growing season.
The compost will slowly break down and provide a wide range of nutrients for the soil for a long time to come.
You can also make your own homemade citrus fertilizer. In the post linked above, I put together a big table that shows all the nutrients from foods you can find in your kitchen and make into fertilizer.
Remember that citrus trees are heavy feeders, check that you’re fertilizing your tree sufficiently, at least once per growing season.
Pests like scale insects may also be one of the reasons for leaf drop in citrus trees. You can remove these pests from the leaves with the help of a sharp knife or a blast of water from a hose. You can also get a cotton swab, soak it in alcohol, and wipe it on the affected areas.
However, if the scale infestation is so bad that it is near impossible to remove manually, you can simply use spray. Aside from the alcohol, you can mix garlic juice, lemon juice, and cayenne pepper. An all-natural option would be to use a neem oil spray.
While overwatering can cause root rot, inadequate water can cause overly dry soil. Both conditions can result in leaves turning yellow and eventually falling off.
A good practice to get into is deep watering as it helps your citrus trees efficiently grow more roots and hold more water in the soil. Not only does deep watering help your citrus trees in times of drought, but the increased moisture in the soil benefits other nearby plants. Again, mulching is also a good idea to minimize evaporation and the soil baking in the sun.
How to Fix Leaf Drop in Citrus Trees
If your citrus tree is currently going through leaf drop, identify the exact cause of the problem so you can fix it before it’s too late. Start with the process of elimination. Here’s a checklist that should help.
- Check for pest or disease
- Check the soil for dryness or wetness
- Shelter the tree from extreme temperatures
- Provide a 2-1-1 NPK fertilizer with a soil pH of 5.5-6.5
First, you need to inspect your tree and its leaves, then check for signs of pest infestation. If you see pests like scales, you spray and get rid of them.
But if you don’t see any, the next thing you need to do is inspect the roots or the soil around the tree. If the soil is constantly moist, even without watering, your tree is likely suffering from root rot. You can confirm by checking the soil near the roots if possible. If the soil is sopping wet or smells like a swamp, root rot has likely started.
If the root rot is severe, you may have to remove the tree from the ground (or the pot) cut off rotten roots, and then replant in new soil. While this can cause transplant shock for the tree and pose a risk, the tree is more likely to survive than if it continued sitting in the stagnant water in the soil.
Temperature fluctuation is easier to address if your citrus tree is in a pot. You can take your citrus tree pot indoors when you expect it to get too hot or too cold outside. You’ll have a better chance of keeping temperatures constant inside the house. Because of this, you can prevent leaf drop and wait for ideal temperatures before moving your tree back outside.
For planted trees, it can be a little tougher, but providing afternoon shade for extreme heat and insulation for frost can go a long way and prevent leaf drop.
Now, when it comes to nutrient deficiency, the only way to fix the issue is by testing your soil’s pH levels and feeding your tree the right kind of fertilizer.
Citrus trees prefer a pH of 5.5-6.5, which is slightly acidic. This is necessary for the tree to properly absorb nutrients from the soil. To maintain healthy citrus trees, fertilize at the start of each growing season. This is different for each type of citrus tree, so become familiar with your tree’s growing season.
Will Citrus Tree Leaves Grow Back?
Leaves can grow back on your citrus tree after a few of them have fallen off. Developing buds are the first sign that your tree is on the road to recovery. However, this only happens if you have addressed the cause of the leaf drop.
If it’s just the change in temperature that caused the leaf drop, your citrus tree will grow back the leaves it lost when the conditions are back to normal. Just give your tree a couple of weeks to recover.
Our lime and potted Meyer lemon tree were both affected by leaf drop, but we were able to identify the issues (over-pruning for the lime tree and extreme temperatures for the Meyer lemon). Now, the lime tree has made a full recovery and the Meyer lemon is doing better staying indoors this winter.
Leaf drop in citrus trees is normal, but when the dropping gets heavy, that should signal a serious problem. Leaves dropping usually comes hand in hand with yellowing. If this is happening to your citrus tree, try to find out what’s causing your tree’s leaves to turn yellow and fall off.
Start by eliminating each problem until you find out what’s causing it. When you’ve managed the issue, your tree should hopefully make a recovery and grow back its leaves.