One of our two lemon trees isn’t growing and we were wondering if there’s anything we can do to speed it up. While I had an idea, I wanted to do some more research. Here’s what I found.
- Only water when the top 2-4 inches of soil gets dry
- Grow in well-draining, sandy loam soil
- Grow in USDA hardiness zones 9-11
- Provide high nitrogen fertilizer 3x per year
- (Optional, but recommended) Provide 2 inches of compost every 1-2 months, and 4 inches of mulch every 3-6 months
- Prune any flowers and fruit off to redirect nutrients and encourage canopy growth until the tree reaches a mature size
So, while lemon trees won’t grow new leaves for several reasons, how can we tell which issue is slowing down lemon trees, and from there—how can we fix it? Let’s take a closer look.
Are Lemon Trees Slow Growing?
Like most hardwood fruit trees, lemon trees are fairly slow growing, growing about 1-2 feet per year. They also require at least 3-5 years to grow and mature before they provide regular amounts of fruit.
This is because lemon trees need time to grow a sufficient canopy and root system to support the weight, water, and nutrient demands of the fruit.
Tip: Lemon trees grown from seed take longer to grow than grafted (cloned) trees from nurseries. For example, expect lemon trees grown from seed to take 5-10+ years to fully mature. This is because they have brand new DNA (like a child) that needs time to mature and develop before it fruits.
When your lemon tree reaches 3 years old, you should start to see regular fruiting (typically blooming in the spring/fall and fruiting in the winter). Here’s an idea of how much fruit to expect from your lemon tree, based on age:
|Age of Lemon Tree
|Amount of Fruit
|3 Years Old
|38 lbs (~152 lemons)
|4-5 Years Old
|over 100 lbs (~400 lemons)
|5+ Years Old
|100-200 lbs (~400-800 lemons)
Now, let’s take a look at the most common reason why lemon trees won’t grow.
1. Improper Watering
According to a study done by the American Society for Horticultural Science, providing lemon trees with moderate amounts of water and regular fertilizer (more on fertilizer later) proved to be the two biggest contributors to canopy and leaf growth.
But, what’s the best way to water lemon trees?
Only water lemon trees by only watering when the top 2-4 inches of soil is dry. This method avoids both under and over-watering.
I check this with the “Finger Test”, by pushing my finger into the soil, under the tree’s canopy. If the soil is wet, hold off on watering. If it’s bone dry, water it.
The goal is to have soil moisture similar to a wrung-out sponge.
However, there are times when the lemon tree’s soil is holding too little or too much moisture. In this case, we’ll need to do more than the finger test.
If you find your lemon tree’s soil is drying within a matter of hours of watering, it’s likely draining too fast. Common symptoms of under-watered lemon trees are leaves curling, drying, browning, and dropping.
Here’s how to fix soil that’s draining too quickly:
- Provide 2 inches of compost every 1-2 months. Compost greatly increases water retention, provides essential nutrients, and promotes beneficial soil life such as earthworms.
- Apply 4-12 inches of mulch. Mulch dramatically decreases evaporation, regulates soil temperature, and prevents erosion. Use mulches such as bark, straw, leaves, and pine needles.
For example, every 1% increase in the soil’s organic matter (compost) leads to an additional 20,000 gallons of water per acre.
For potted lemon trees, I also suggest applying 2 inches of compost. You can still mulch around the base, but you may have to use less depending on how much room is left in the pot. Mulching indoor lemon trees isn’t as necessary and can lead to mold or bugs from the trapped moisture.
You can tell if your lemon tree is over-watered if its soil is staying sopping wet for more than 24+ hours after watering. Common symptoms of over-watered lemon trees include yellow and dropping leaves and root rot (more about root rot later).
Here’s how to fix over-watered lemon trees:
- Apply 2 inches of compost every 1-2 months. Interestingly, compost also fixes over-watering. This is because compost not only retains soil moisture but breaks up the larger clumps of soil, allowing proper drainage.
- Avoid mulching your lemon tree until the soil is draining properly. In this case, mulching decreases evaporation and can make over-watering and poor drainage worse.
For potted lemon trees that are over-watered or waterlogged, the best way to amend the soil is to repot them with fresh potting soil.
2. Extreme Weather
For best results, grow lemon trees in USDA hardiness zones 9-11. This is between 20ºF and 90ºF. While lemon trees can tolerate temperatures slightly above and below these ranges, this guideline will help them grow best.
Let’s take a look at the climates that lemon trees prefer.
Too Hot and Dry
When lemon trees are exposed to temperatures of 90ºF and above, their leaves get too hot which stresses the plant and hinders the growth of leaves and fruit. In this case, the plant can’t send moisture from its roots to its leaves fast enough, which causes the leaves to dry, curl, brown, and drop.
As lemon trees are tropical plants, they generally do best in warmer climates. However, they can be grown in cooler climates if grown indoors or in greenhouses.
Avoid growing lemon trees in dry climates as they prefer higher humidity. Still, lemon trees can grow in dry climates especially if they have regular watering and other plants nearby (to increase humidity via transpiration).
Aside from watering when the soil is dry, here are some other ways to keep your lemon tree cool:
- Provide 2 inches of compost for water retention
- Apply 4-12 inches of mulch for insulation
- Provide at least 2 hours of partial shade in the afternoon. You can use shade sails, structures, or other trees to create shade
Since lemon trees are native to the tropics, it’s easy for them to get cold. For example, most varieties can tolerate down to 20-25ºF. After that, lemon trees begin to die.
However, I found that lemon trees stop growing and decline even in slightly warmer temperatures.
When I lived in Austin, Texas (Zone 8b), I had a potted lemon tree. While I thought I could push the recommended zones of 9-11, when the temperature dropped below 55ºF, I noticed my lemon tree stopped growing. When it dropped below 32ºF, the lemon tree began to lose leaves and die.
Here’s how to keep your lemon tree warm when temperatures dip below 32ºF:
- Provide 4-12 inches of mulch for root insulation
- Cover the canopy with a bedsheet to reduce windchill and frost buildup
- Wrap the trunk with cardboard or another insulating material
- Bring potted lemon trees inside, but keep them away from the central heat as it dries out their leaves (I ran into this issue myself).
Not Enough Sunlight
Lemon trees require at least 6 hours of direct sunlight a day. While some lemon trees can grow with as little as 4 hours per day, you’ll often see reduced growth the fewer hours the plant receives.
Sunlight is critical for plant and fruit growth as it encourages photosynthesis, or how the plant gets its food and water.
If your lemon tree’s leaves are curling or browning, it could be a sign it’s getting too hot and could use some water, and shade from the afternoon sun.
In this case, use the shade from other trees, structures, or items such as shade sails. 2+ hours of daily, partial shade from the western sun will work.
Here are some tips to boost the sunlight for your lemon tree:
- Plant on the south side of your property for maximum sunlight (if you live in the southern hemisphere, this is the north side).
- Place the tree near a south-facing wall to allow heat and sunlight to reflect onto the tree (however, you’ll likely need to provide it with more water than usual)
- Prune any trees above the lemon to allow for more sunlight. You can also prune the lemon tree’s excess and overlapping branches to increase sunlight and airflow into the canopy (and reduce pest and disease exposure).
3. Improper Nutrients
Excess nutrients (over-fertilizing) chemically burn the lemon tree’s roots, causing stress and leading to poor growth as well as decreased flowering and fruiting. Normally, fast-release chemical fertilizers are the cause of over-fertilization as organic fertilizers and compost aren’t potent enough.
Lack of Nutrients
|Entire leaf is pale or yellow
|Dark green veins, rest of the leaf is yellowing
|Broadly pale leaves, foliage color looks mottled or smeared
A lack of nutrients also stresses the tree, leading to similar conditions such as stunted growth and little to no flowers and fruit. This is commonly caused by poor soils, leaching, and other conditions such as improper pH.
Nutrient leaching occurs when the nutrients seep too far down into the soil, out of reach of the plant’s roots (beyond about 2-3 feet). This normally happens when soils have too much drainage or are over-watered. For example, sandy soils are notorious for their leaching properties.
Fortunately, most of these issues can be resolved by properly fertilizing lemon trees.
The Best Way To Fertilize Lemon Trees
The three main nutrients for lemon trees (and most plants) are nitrogen, phosphorus, and potassium (NPK). Nitrogen is by far the most important (vital for root and canopy growth), but phosphorus and potassium are essential for flowering, fruiting, and the overall health of the tree.
The two main ways to fertilize your lemon tree are with fertilizer or compost. If you choose a store-bought fertilizer, aim for one with an NPK with double the nitrogen. For example, use a 6-3-3 NPK.
Tip: Citrus trees aren’t the only fruit trees that prefer double the nitrogen. Avocado trees are also heavy feeders and require plenty of nitrogen to grow properly.
Chemical Fertilizer vs Organic Fertilizer vs Compost
I do recommend organic fertilizers and compost over chemical fertilizers. While chemical fertilizers have nutrients in quantity, they typically don’t have quality nutrients.
Even though chemical fertilizers might be sufficient over the short term, over the long term they often short-circuit the nutrient exchange between the tree and its beneficial soil life (such as mycorrhizal fungi). This leads to dry and dead soil (AKA dirt) and overall decreased plant health.
Mycorrhizal fungi promote many aspects of plant life, in particular improved nutrition, better growth, stress tolerance, and disease resistance.Department of Biology, University of Fribourg, Switzerland
On the other hand, organic fertilizer and compost provide more than sufficient nutrients, increase water retention, and promote healthy soils. Many gardeners are even finding that compost is replacing their fertilizers.
If you choose to use compost, select one with the highest quality and freshness if possible as its beneficial organisms will still be alive.
Tip: Grow nitrogen-fixing companion plants such as acacia or pigeon pea and use their branches as mulch (chop and drop) to provide amazing nutrients to your lemon tree.
Either one you choose—you can see my recommendations for both compost and fertilizer on my recommend fertilizer page.
When to Fertilize Lemon Trees
According to Down to Earth and The University of Arizona Cooperative Extension, lemon trees should be fertilized 3 times per year:
Because lemon trees are evergreen (keeping their leaves year-round) and commonly fruit 1-2 times per year, they typically require more frequent fertilizer application than cold-climate plants.
So, to recap:
- Provide organic fertilizer with double the nitrogen (such as a 6-3-3). Apply three times a year if possible.
- (Optional, but recommended) Provide 2 inches of compost every 1-2 months and 4 inches of mulch every 3-6 months
Lemon trees do best with a soil pH of 6.0 to 7.0
While nutrients are important, they’re next to useless if the soil does not have a proper pH. This is because a slightly acidic pH is necessary to dissolve the nutrient solids in the soil and make them accessible for the plant’s finer roots.
Fourteen of the seventeen essential plant nutrients are obtained from the soil. Before a nutrient can be used by plants it must be dissolved in the soil solution. Most minerals and nutrients are more soluble or available in acid soils than in neutral or slightly alkaline soils.Donald Bickelhaupt, Instructional Support Specialist, Department of Forest and Natural Resources Management
Two good ways to check your soil’s pH are either by using a pH strip or a pH meter. I prefer using a pH meter since they’re affordable and easy to use. To see which pH meter I use and recommend, check out my recommended tools page.
If you find that your lemon tree’s soil is too alkaline (above 7.0) you can add acidic amendments such as coffee grounds, sand, and peat moss. On the other hand, if your lemon tree’s soil is too acidic (below 6.0), add alkaline materials such as wood ash, charcoal, or lime.
Additionally, cold and/or wet soils are not good at promoting nutrient uptake as the lemon tree will either be dormant during the cold or too stressed in wet soils.
4. Transplant Shock
If your lemon tree was recently planted or repotted, and its leaf growth has slowed or stunted, it’s likely due to transplant shock. Transplant shock occurs when a plant is exposed to a new environment and has to establish a new root system.
In this case, the lemon tree is stopping its canopy growth to instead regrow its roots.
Avoid transplanting lemon trees unless necessary as it can take up to 1 year for recovery.
To help avoid transplant shock, I like to plant with the following steps in mind:
- Have the new ground (or pot) prepared
- Remove as much of the plant’s current topsoil as possible, without damaging the shallow roots
- Grab the base of the plant’s stem and wiggle lightly
- Using your other hand, scoop up and support the rootball
- Lightly place the plant in the new ground (or pot) and fill it in
- Make sure the soil is at the same level on the plant as before
- Apply 2 inches of compost and 4-12 inches of mulch to the top of the soil
- Water generously and add more soil as needed
Aphids are small bugs that suck the sap from underneath the lemon tree’s leaves. This loss of sugar and moisture causes the leaves to curl, discolor, and drop. Aphids also deposit honeydew, which attracts ants.
If left unchecked, aphids can damage the lemon tree’s health and potentially stunt or kill it.
These bugs come in multiple colors including white, yellow, or black, and usually are found hiding underneath the leaves. Typically, aphids won’t cause damage to the fruit, but because they suck sap from the plant, they can compromise its health and therefore reduce fruit size and yield.
The best ways to get rid of aphids (and spider mites) on lemon trees is by spraying the infected leaves with water or neem oil, or releasing ladybugs (a natural predator of aphids and mites). Most often, a jet of water is enough to knock them off and kill them, but neem oil is a good second option.
For example, when my potted Kaffir lime tree had aphids, I found that a jet of water was sufficient to blast them off and prevent them from coming back. All I did was remove the hose nozzle and used my thumb to increase the pressure. Just keep in mind that too strong of a blast can damage the leaves.
To attract ladybugs to your garden, you can plant lemon tree companion plants such as dill, fennel, and yarrow.
Spider mites are similar to aphids, except they’re part of the spider family. They also feed on lemon trees and cause stunted growth as well as leaves turning yellow, red, and dropping.
The main differences in appearance between aphids and spider mites are the spider mite’s ability to spin webs. These webs can cause damage to other parts of lemon trees such as the twigs and fruit.
So, if you see small dots on your lemon trees, see if they’re depositing honeydew or webs and you’ll likely identify if they’re aphids or spider mites.
Remember, the methods to treat aphids on your lemon tree are the same as spider mites.
Root rot kills off the lemon tree roots, which stresses the plant and causes symptoms such as fruit, flowers, and leaves yellowing, browning, and dropping. If not addressed, it leads to stunted growth or a dying lemon tree.
You can typically tell if your lemon tree has root rot if the soil is staying sopping wet and starts smelling. Allowing the soil to dry out or repotting lemon trees with fresh potting soil are the best ways to amend this disease.
For example, I noticed my potted Kaffir lime tree had root rot as its soil smelled swampy and was staying wet for many days at a time. In this case, I repotted it with fresh potting soil, and the tree quickly recovered.
Verticillium wilt is a fungus that is similar to root rot in that it usually occurs in soils with excess water. Additionally, over-fertilizing can also cause it.
The most susceptible fruit crops that contract verticillium wilt are nightshade (tomatoes, peppers, and eggplants), but other fruiting plants such as lemon trees can also be infected. Symptoms of this disease include leaves wilting, yellowing, and dropping, and potentially branch dieback.
Prevent and treat verticillium wilt by pruning infected branches, avoiding excess water and fertilizers, and following best gardening practices.