I’ve had my Meyer lemon tree for a while now, and there was a time when its leaves were turning brown at the tips. I was worried the browning would get worse and lead to leaf drop, so I did some research to find out what causes it and how to fix it. Here’s what I found.
Lemon trees get brown leaves from a lack of water or a buildup of salts in the soil. These salts are typically caused by hard water or too much fertilizer and can be flushed out with soft water. For best results, use rainwater, avoid fertilizing in the winter, and use well-draining soil.
So, while lemon trees most commonly get brown leaves from dryness or excess salts, what are more details around this, and what can we do to fix it?
Under-Watering
Lemon tree leaves can curl and brown if they get too dry. Typically, this is from a lack of water, but extreme heat or dryness can also cause it. To prevent this, keep the tree’s soil moist, and avoid temperatures of 100ºF or more. You can bring potted lemon trees indoors, but avoid placing them near central heat.
Like all trees, lemon trees need to have sufficient moisture in their soil to thrive. Since they’re native to the tropics, they’re used to plenty of water and high humidity.
When starting to dry, their leaves will curl or droop to conserve moisture. If not addressed, they’ll dry completely and turn brown in the process.
Of course, depending on the weather, the soil can get drier faster and require more water. This can make growing them in hot and dry climates, such as Arizona or California, challenging.
So, what’s the best way to water lemon trees?
How to Fix
The best way to water your lemon tree is to only water when the first 2-4 inches of soil gets dry. You can check this by pushing a finger into the soil, up to the second knuckle. For best results, use 1-2 inches of both compost and mulch on top of the soil to improve water retention and reduce evaporation.
Aside from watering, it’s also important to make sure the lemon tree’s soil has proper drainage.
Too much drainage and the soil will dry out quickly. Too little drainage and the soil will hold excess water, leading to root rot and other conditions such as yellow leaves.
This is why checking your lemon tree’s soil is the best way to gauge how much water it needs. And you can do this by simply using a finger. Push it into the soil, up to the second knuckle and feel how dry or wet the soil is.
Soil should not be bone dry or sopping wet but have consistent moisture.
If you find that the soil remains sopping wet at least 1 hour after watering, it most likely needs to be amended to promote better drainage. You can do this by adding sand or perlite to the top of the soil. Over time, these materials will be worked down into the soil. Transplanting or repotting your lemon tree should be saved as a last-resort solution.
On the other hand, if your lemon tree’s soil is draining or drying too fast, use compost and mulch.
Compost improves the richness of the soil, which increases water retention. For example, each 1% increase in a soil’s organic matter can help hold 20,000 gallons more water per acre.
Mulch drastically reduces evaporation from the soil and protects it from drying in the sun and wind. Soil can easily bake from strong sunlight, while high winds can act as a blow dryer.
The goal is for the soil to hold moisture for at least a few days, and ideally for a week.
If your lemon tree is potted and indoors, make sure not to place it near any central heat vents (I accidentally did this and it caused more dryness and leaf loss).
While this might be a lot of information, these techniques will help make sure your lemon tree receives the right amount of water.
In short, use the finger test and water only when the soil is dry. Add compost and mulch as needed to protect the soil from drying out too fast.
Compost can also usually replace fertilizers (more on this later)!
Excess Salts
Salt buildup in the soil can cause brown leaves on lemon trees. Generally, these salts are accumulated from hard or treated water (such as tap water). Over-fertilizing can also lead to excess salt in the soil. To reduce salt buildup, avoid fertilizing in the winter, flush the soil, and use rainwater if possible.
Let’s take a closer look at what causes salt buildup in the soil and how we can reduce (and fix) it.
Hard Water
Just like how we perform better with healthy food and clean water, so do trees. While we’ll cover fertilizer and nutrients in the next section, what exactly makes water clean (or dirty)?
Tap and irrigated water can often be heavily treated with added minerals and chemicals, which then accumulate as the water evaporates—leaving salts in the lemon tree’s soil. Most commonly, these excess salts are chlorine and sodium salts.
Salt accumulation is more common with potted lemon trees as they have a limited amount of soil to work with. This is because planted lemon trees have much more soil and benefit from getting regular flushes from rainfall. More salt can also build up if the soil has poor drainage.
Since the solution is similar to that of over-fertilizing—I’ll include them both together below.
Over-Fertilizing
Salts can build up in soil if you provide your lemon tree with excess fertilizer. While lemon trees are evergreen, and not too dormant in the winter, they can still benefit from a break from fertilizers during this time. If the soil has poor drainage, it can easily be overpowered by fertilizers.
Like hard water, fertilizers contain different chemicals and salts, all of which can accumulate in the soil. This can especially be a problem if the lemon tree gets a potent and frequent dose of fertilizers.
How to Fix
The best ways to reduce salt buildup in the soil are to flush the soil, use rainwater, and switch to compost. You can flush the soil by watering for 5 minutes. If rainwater is not possible, you can use reverse osmosis water or let the tap water sit for 4.5 days for the chlorine to evaporate.
These are the 3 best ways to reduce salts from building up in your soil:
- Flush the soil
- Water with soft water
- Switch from chemical fertilizers to compost
Flushing the soil will help dissolve the salts and push them further down into the soil (or drain out of the pot). A good way to do this is by watering the soil under the lemon tree’s canopy for 5 minutes with soft water.
Rainwater is the best soft water to use and trees absolutely love it (more on soft water below).
While chemical fertilizers can be convenient and are easy to use at scale, they have many downsides including damaging the soil and tree’s health. If using fertilizers, use organic, slow-release fertilizers when possible and follow the instructions and amount listed on the package.
Lemon trees do best with a fertilizer that has twice the nitrogen to phosphorus and potassium (NPK), such as an NPK of 6-3-3. Compost is also a great source of nutrients.
If you’d like my recommendation for the best lemon tree fertilizers, check out my recent post: The Full Guide to Lemon Tree Fertilizer (& The Top 3 Brands).
Alternatively, you can use compost, which not only provides a rich supply of nutrients to the tree but also promotes beneficial soil life and helps retain water.
How To Get Soft Water
Rainwater is simply the best water to use for any of your plants. Some benefits of watering with rainwater include:
- 100% soft water
- Slightly acidic
- Contains nitrates
Soft water means it has little to no harsh chemicals or minerals, while the acidity and nitrates (nitrogen) are great for acid-loving lemon trees.
However, if rainwater is not possible in your area (if you have limited rainfall, live in an apartment, etc.), other methods can reduce the hardness of your water.
Reverse osmosis water is a method to purify water by using pressure to push it through special filters. While reverse osmosis systems can be a bit expensive to install, you can also buy the water separately. For example, I buy my RO water at Whole Foods in 5-gallon jugs. Even though we mostly use it for drinking, I have watered some smaller potted plants with it.
Distilled water is similar to reverse osmosis, just slightly less clean. Distilled water is essentially made by collecting steam. It’s still a great option to water your lemon trees, especially compared to tap water.
However, if you do use tap water, there are a few ways you can reduce the chemicals and salts from building up.
Chlorine is commonly found in tap and irrigated water as it helps disinfect it. Unfortunately, it also causes chlorine salts to build up. Different types of water will have different levels of chlorine.
| High Chlorine Water | Low Chlorine Water |
|---|---|
| Tap water | Rainwater |
| Irrigation water | Chlorine-evaporated water |
| Most other treated waters | Charcoal-filtered water |
Luckily, an easy way to reduce the chlorine in tap water is to let it sit, uncovered, for 4.5 days. By doing so, most of the chlorine will evaporate, which means much less for your lemon tree’s soil.
Some other ways to flush the salts from the soil are to use vinegar or add chemical amendments such as gypsum or calcium chloride. While using vinegar is fairly easy to do, chemical amendments can be a bit more complex.
How To Test for Salts in Soil
If you believe you have salts that built up in your soil and would like to confirm it with a test, you can send a sample out to a testing laboratory. I’m not sure about other states, but here in Texas, you can send your soil sample to the Texas A&M AgriLife Extension Service.
Check for Pests and Disease
While the above sections are the most common reasons why lemon trees get brown leaves, if you’re noticing the leaves getting brown spots instead, it could be from a pest or disease.
Inspect the top of your lemon tree’s leaves for any small, circular, brown spots. Additionally, check the underside of the leaves for any white, yellow, or black dots (which are most likely aphids).
Even though there aren’t many pests and diseases that can cause brown leaves on lemon trees, they can vary from region to region. To get the most accurate information about your specific region, check with your county extension office.
Final Thoughts
Today, I’m letting my tap water sit for several days to reduce the chlorine and feeding my plants with compost instead of chemical fertilizers. Because of this, my Meyer lemon tree is doing much better, but I’m still keeping an eye on it and seeing if it gets any other brown or dropping leaves.
If it gets brown leaves in the future, I now know to check the amount of water it gets, if it’s hard or soft water, and if it has any other buildup of salts!
