There was a time when our lime tree wouldn’t fruit and we weren’t sure why. After doing some research, I found out some reasons why and today it has plenty of fruit. Here’s what I found.
Lime trees won’t fruit due to a lack of age, pollination, watering, sunlight, and nutrients. Some pests and diseases also cause little to no fruiting. Ideally, only water when the top 2-4 inches of soil is dry, apply organic fertilizer or compost, and provide 6+ hours of sunlight per day.
So, while lime trees won’t fruit for several reasons, how can we tell what the issue is, and from there—how can we fix it? Let’s take a closer look.
1. Not Yet Mature
Before a lime tree fruits reliably, it needs to first establish a mature canopy and root system to collect nutrients (via the sun and soil minerals). After that, it will have enough resources to flower and fruit.
To know your lime tree’s fruiting potential, it’s helpful to know the difference between a grafted lime tree and one grown from seed.
Grafting
Grafted lime trees will fruit within the first 2-3 years.
Grafted lime trees are essentially a clone of an existing tree. This is done by taking a clipping of a branch (or cutting) and growing it into another tree. If you bought your lime tree from a nursery, it’s most likely grafted.
Grown from Seed
On the other hand, lime trees that are grown from seed can take between 5-10 years to start flowering and fruiting.
This is because a tree grown from seed has brand-new genetics and requires more time to mature (more like a child than a clone).
Grafted trees use budwood from an already mature tree, so they’re essentially a clone and don’t need to wait to mature. Trees grown from seed are a child of the original tree (with brand new DNA) and need to properly mature before flowering and fruiting.
Lime trees normally fruit year-round, with May-June and November-December being the heavier fruiting months.
So, if your lime tree isn’t of age, then it likely explains why it doesn’t have normal fruit sets yet. Once it matures and establishes a canopy and root system, it should start fruiting regularly.
To find out if your lime tree is grafted or grown from seed, contact your seller or inspect the tree to see if you can find a grafting scar.
But what if your lime tree is mature and it’s still not producing fruit?
2. Lack of Pollination
While most lime trees are self-pollinating, they do best if they are cross-pollinated.
“Although it has been suggested that cross pollination on Washington Navels is not required to increase yield, there is evidence to show that pollination by bees may contribute to less fruit drop.”
Malcolm T. Sanford, University of Florida
While the above quote mentions fruit drop for orange trees, it’s also true for lime, citrus, and most other fruiting plants.
Because of this, plant multiple lime trees of the same variety within 50 feet of each other. This is the appropriate distance between trees so pollinators have the best chance to visit both trees.
Some other ways to boost pollination are:
- Companion Plants
- Beekeeping (one hive recommended per 2 acres of grove)
- Manual Pollination
If you’d like to manually pollinate your lime tree’s flowers, use a clean paintbrush, toothbrush, or Q-tip, and lightly brush from flower to flower.
While you can plant lime of different varieties, you’ll likely get hybrid fruits (which some people prefer).
Keep in mind to overlap the flowering times of your lime trees to ensure the best pollination. An easy way to do this is to plant 2 or more of the same variety.
Now, if you have plenty of flowers and pollinators flying around, and your lime tree still isn’t fruiting, the next potential issue to look at is watering.
3. Improper Watering
| Over-Watering | Under-Watering | |
|---|---|---|
| Symptoms | Yellow or Dropping Leaves | Curled, Dried, Browned, or Dropped leaves |
| Soil Quality | Soaking Wet Soil (for over 24 hours) | Bone Dry Soil |
| Solution | Finger Test and Compost | Finger Test, Compost, and Mulch |
Lime trees that are over or under-watered are typically too stressed to produce fruit. This is because the water that is available is used to support the tree’s primary functions (such as the root, canopy, and immune systems).
If the lime tree’s watering is not addressed in time, these systems begin to fail and you’ll see symptoms.
The best way to water lime trees is to only water when the first 2-4 inches of soil is dry. This prevents both over and under-watering.
I check this by pushing my finger into the soil (“the finger test”). If the soil is wet, hold off on watering. If it’s dry, water it.
However, there are times when you need to amend the soil, either for better drainage (over-watering) or for better water retention (under-watering).
Compost is the best solution for both under and over-watering as it both retains water and provides proper drainage. It does this by adding organic matter to the soil, allowing water to flow not too fast and not too slow.
For example, every 1% increase in the soil’s organic matter holds an additional 20,000 gallons of water per acre. Compost also provides essential nutrients and promotes beneficial soil life such as earthworms and mycorrhizal fungi.
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
For best results, apply 2 inches of compost every 1-2 months.
For under-watered lime trees, I also recommend providing 4-12 inches of mulch every 3-6 months such as leaves, wood chips, or straw. Mulch dramatically reduces evaporation, regulates soil temperature, and prevents erosion. Apply the mulch on top of the compost.
However, avoid using mulch for lime trees that are over-watered or have poor drainage. The reduced evaporation effects of mulch can make these issues worse. Once the soil has proper drainage, start putting on layers of mulch.
Keep both materials at least 3 inches from the lime tree’s trunk to avoid mold buildup.
4. Extreme Weather
As lime trees are from the subtropics, they prefer plenty of heat and sunshine. For best results, keep lime trees between 25ºF and 90ºF. If it gets hotter or colder, the tree can become too stressed to produce fruit and can take up to a year to recover.
Like other citrus trees, lime trees prefer USDA hardiness zones 9-11. To see which hardiness zone you’re in, use the link provided above in the image caption. If you’re outside of these zones, consider establishing a microclimate (such as greenhouses, food forests, etc.)
Hot & Dry Weather
When temperatures are too hot or dry, lime trees can lose much of their stored water. This is made worse if the soil also becomes dry (which is why composting and mulching are so important).
It may be helpful to know that lime trees keep themselves cool by sending moisture from their roots to their leaves and through a process called transpiration.
Transpiration is when plants exhale moisture (much like how we do). This is the reason why walking into a dense forest can feel extremely humid.
Professional German forester Peter Wohlleben mentions in his book, The Hidden Life of Trees, the top side of a leaf is generally as a solar panel (photosynthesis) while the bottom side is for breathing (transpiration).
The problem occurs when transpiration and root moisture can’t keep up with the extreme heat and dryness. It loses more moisture than it gains, causing curled, dried, browned, and dropped leaves.
Here are some tips to help cool your lime tree:
- Apply 4-12 inches of mulch for reduced evaporation
- Apply 2 inches of compost for better water retention
- Provide 2+ hours of partial shade from the west sun (the afternoon sun is the hottest). You can use shade sails, structures, or other trees
Cold Weather
Most varieties of lime trees don’t like frost (under 32ºF), but can typically survive down to 25ºF. If temperatures drop below this, or stay cold for too long, the lime tree can die.
Symptoms of a lime tree affected by frost are brown and dropping leaves (green leaves can drop as well). You can tell if a lime tree is still alive by scratching or pruning a small branch and seeing if there’s still green inside.
Here are some tips to keep your lime tree warm:
- Apply 4-12 inches of mulch for insulation
- Cover the canopy with bedsheets of canvas in times of frost
- Insulate the trunk with cardboard or other insulating materials
As mentioned earlier, planting in or establishing a microclimate can help your lime tree survive in times of extreme weather. Even an adjustment of a few degrees can mean the survival of your lime tree.
To learn more about microclimates, check out this helpful video by Gardener Scott.
5. Improper Nutrients
Excess Nutrients
Too many nutrients are often caused by fast-release chemical fertilizers as compost isn’t potent enough. When this happens, the tree’s roots can become chemically burned, causing the tree stress and leading to a decline in health and fruiting.
If you believe you’ve over-fertilized your lime tree, I suggest removing as much of the fertilizer as possible via leaching. To do this, soak your lime tree’s soil to dilute the existing fertilizer and allow it to flow deeper into the soil (out of reach of the tree’s roots). You may have to do this at least a few times.
However, avoid leaching if your soil has poor drainage as the soil can become waterlogged. In this case, either apply generous amounts of compost and garden soil or repot the tree with fresh potting soil (for potted lime trees).
Lack of Nutrients
| Nutrient Deficiency | Leaf Symptom |
|---|---|
| Nitrogen | Entire leaf is pale or yellow |
| Iron | Dark green veins, rest of the leaf is yellowing |
| Zinc | Yellow blotches |
| Manganese | Broadly pale leaves, foliage color looks mottled or smeared |
If you haven’t fed your lime tree in the past several months, there’s a good chance a lack of nutrients is causing little to no fruiting.
However, symptoms of a lack of nutrients depend on the deficiency.
For example, lime trees commonly get a nitrogen deficiency (they require double the nitrogen compared to other fruit trees) and get lightly colored or yellow leaves. This is more likely in younger lime trees as nitrogen is the primary nutrient needed for growing a canopy.
Let’s take a look at the optimal way to prevent a lack of nutrients for your lime tree.
The Best Way To Fertilize Lime Trees
If you decide to use a fertilizer, opt for one with double the nitrogen to phosphorus and potassium (NPK) such as a 6-3-3. Each brand has different potencies, so follow the instructions on the label for the best results.
Alternatively, use compost. I recommend applying 2 inches of compost every 1-2 months under the tree’s drip-line (canopy). Applying mulch on top of the compost goes a lot further and adds to the water retention and nutrients.
Generally, I prefer using compost over fertilizers, and many gardeners are finding that compost is replacing their chemical fertilizers.
Either one you choose, if you’d like to see which fertilizers and compost I recommend, check out my recommended fertilizer page.
Keep in mind that while nutrients are essential, they aren’t everything.
Imbalanced Soil pH
When lime trees have an imbalanced soil pH, they can develop issues such as poor fruiting as well as discolored and dropping leaves. Additionally, their flowers and fruit can drop early and the tree is more likely to develop other issues.
Lime trees prefer a soil pH of 6.0 to 7.0.
The reason lime trees (and most plants) prefer a slightly acidic soil pH is that it helps dissolve the nutrient solids in the soil, making them more accessible to 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 test your soil’s pH are with pH strips or a meter. I prefer using a pH meter since they’re affordable and easy to use. To see which pH I recommend, check out my recommended tools page.
If you find your lime tree’s soil is too alkaline (above 7.0), provide acidic amendments such as peat moss, sand, and coffee grounds.
On the other hand, if your soil is acidic (under 6.0), provide alkaline amendments such as charcoal, wood ash, and lime (ground limestone).
6. Pests and Diseases
Aphids
Aphids are small bugs that suck the sap from underneath the lime tree’s leaves. This loss of sugar and moisture causes the leaves to curl, discolor, and drop.
When aphids suck the plant’s sap, they deposit honeydew—which attracts ants. If left unchecked, aphids can damage the 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 mites) on lime 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.
Root Rot
Root rot, also called Phytophthora Root & Crown Rot, is a root fungus that causes lime tree leaves, blossoms, and fruit to droop, yellow, brown, and drop.
This disease typically occurs in areas with poor drainage. To prevent and treat root rot, promote well-draining soils and transplant young trees with fresh soil if necessary. Raised beds or planting in mounds of soil are also helpful in improving soil drainage.
There is no chemical control available for crown and root rot in the home garden. The most important control strategy is careful water management.
Clemson University Cooperative Extension Service
My potted Kaffir lime tree had root rot recently, which I was able to tell based on the sopping wet soil and swampy smell. Fortunately, after repotting the tree with fresh potting soil and waiting a few days, the tree made a full recovery!
