Native to Northeast India and South Asia, Citrus limon trees, better known as lemon trees, are evergreen trees belonging to the Rutaceae plant family.
Lemon is popular for eating raw, adding to drinks, making juice, and as a main staple in lemon meringue pie.
Believe it or not, it is also known for its acidic properties that make it an excellent ingredient in homemade cleaning supplies.
Growing lemon trees is simple enough, compared to many fruit trees. That said, there are a few tell-tale signs that something may be wrong with your lemon tree, including curled leaves and leaf drop.
Why Does Lemon Tree Leaf Drop Happen?
Lemon tree leaf drop is caused by a host of reasons, including environmental issues and human error. Overwatering, too much or too little sun, excess winds, fungus, disease, and pests, top the list why leaves drop from your lemon tree.
10 Reasons and Remedies for Lemon Tree Leaf Drop
Many times, the reason for lemon trees dropping their leaves is simply overwatering.
To avoid this common issue, evaluate your watering schedule and readjust to a more suitable amount of water for lemon trees.
New lemon trees need watering on alternate days for the first few weeks. Afterward, they should be watered no more than once every week.
The older the tree becomes, the less it needs watering.
Two-year-old lemon trees, and older, that are outside, require watering just once every two to three weeks when it’s dry. Indoor trees should only be lightly watered once a month.
If the leaves falling from your tree show signs of something eating them, mold, or other strange markings, the culprit is most probably pests.
Depending on the area you’re living in, there are numerous pests to look out for that may affect your lemon tree.
To remedy the issue, you’ll first need to identify the specific type of pests causing your leaf drop problem.
Once you know what sort of bugs you’re dealing with, choose a proper oil, spray, or powder-based pesticide and apply it as needed.
A simple issue to fix, but one that many folks overlook is cold temperatures. Being Citrus trees, lemon trees do not do well in any temperatures below 50 degrees Fahrenheit.
That said, some varieties may not begin dropping leaves, or taking damage in general until temperatures drop down to below freezing (32 degrees Fahrenheit).
To combat this problem, either bring your lemon trees inside for the colder parts of the year or cover them up outside.
Also, make sure to water your tree a couple of days or so before freezing temperatures occur.
4. Root Rot
Lemon trees also drop leaves due to root rot. The soil-borne pathogen Phytophthora is one of the main reasons for root rot development on lemon trees.
Likewise, overwatering, especially coupled with poor drainage, may cause root rot.
Keeping the base of your tree clear of debris, including weeds, grass, and low-growing plants, is one of the best ways to prevent root rot from happening.
Another great remedy for root rot, and leaf drop in general, is improving your tree’s irrigation or drainage.
5. Leaf Spot Disease
Leaf Spot disease is another issue that causes leaf and fruit drop. Identify Alternaria, or Leaf Spot, by the blackish color it produces in the veins of leaves and dark pits with yellow rings on the lemons themselves.
Planting disease-resistant species and keeping your trees spaced properly is your first line of defense against Leaf Spot disease.
In addition, spraying fungicides onto your trees’ leaves when the leaves begin opening in the spring, and again once they’ve opened all the way, is another method for beating Alternaria.
If yellowish-brown spots and blisters accompany your lemon tree’s leaf dropping, you are more than likely dealing with one of the most common fungal species that affect lemon trees, Greasy Spot fungus.
This particular fungus not only causes leaf drop, but it also makes your tree more prone to pests, cold, and other issues.
To combat it, and other fungi, spray your trees with copper fungicide during early summer and again in late summer. Make sure to cover all of the leaves, including the undersides.
7. Moving From Inside to Outside
When you move your lemon tree from inside to outside, typically in the spring, it should be done with great care and attention.
Failure to “harden” your tree to the weather may result in serious leaf drop.
Hardening is a process in which you gradually expose your indoor plants or trees to the sun, and outdoor temperatures, a few hours at a time, over the course of several days, before placing them outside to stay.
However, once your tree is acclimated to the temperature and environment outside it should begin to start growing new leaves within a couple of weeks.
Likewise, fruit production should take place as normal.
8. Lack of Nutrients
A lack of nutrients is another of the most common issues that cause leaf drop in lemon trees.
The best way to make sure your trees are receiving enough nutrients is by feeding them with fertilizer for fruit trees, which includes one pound of nitrogen, at least once per year.
That said, if your trees are smaller than 15-feet in diameter, it is more effective to give them much smaller doses of fertilizer each month when watering them rather than fertilizing them once per year.
9. Not Enough Sun
Another common problem that causes leaf drop with lemon trees is a lack of sunlight. For the best results, lemon trees require around eight hours of sunlight daily.
For outside trees, take care to place them in a spot that gets full sun for an adequate amount of time.
10. Too Much Wind
Last but not least, your tree may be suffering due to copious amounts of wind. A bit of airflow is good for your lemon tree, but constant wind isn’t.
For this reason, inside trees should be situated out of the way of fans or air conditioners that are frequently blowing.
Likewise, outside trees do best when they are near some sort of wind block in place. This could be a row of bushes, other trees, a fence, or even a wall.