We have a few avocado trees and every now and then one of them starts to die for seemingly no reason. I wanted to find out more, so I did some research. Here’s what I found.
Avocado trees most often die from improper watering, climate, and nutrients, as well as pests and diseases. Ideally, only water when the soil is dry, and apply 2 inches of compost and 4-12 inches of mulch under the canopy. Avocado trees grow best in USDA hardiness zones 8-11, which are generally between 15ºF to 90ºF.
So, while avocado trees die for many reasons, how do you identify the issue, and how can you fix it? Let’s take a closer look.
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Can Dying Avocado Trees Be Saved?
A dying avocado tree can be saved if the issue is caught early and it hasn’t done too much damage. For example, if under-watering is the issue, and the tree has only lost a few leaves, it’s reasonable to expect the tree to make a full recovery.
However, if the tree is drought stressed to the point where it lost all of its leaves, the tree might not make it. At this point, it’s up to the existing stored energy in the tree and roots if the tree will survive and grow new leaves.
3 Steps To Save a Dying Avocado Tree
If you’ve already tried finding out which issue your avocado tree has, and you’ve gotten stuck, there’s still hope.
Here are 3 steps you can use to save your avocado tree, for just about any condition.
1. Identify the Possible Issues
The first step in reviving a dying avocado tree is to identify the possible issues. After all,the process of elimination wouldn’t work if we didn’t know which options we were eliminating!
If you haven’t seen them yet, reference the below sections for the top 6 most common avocado tree issues.
2. Isolate the Actual Issue
Once you’ve checked the specific symptoms your avocado has, you can now cross off potential issues from your list.
Try to get it down to 1-3 potential issues that best match the symptoms your avocado tree is exhibiting. This will give you the best chance to provide the right solution for it (you don’t want to repot the plant if the problem is a watering issue).
3. Test Solutions
Now that you have a narrowed-down list of the potential issues, it’s time to try the solutions one at a time.
Start with the least invasive solution and work your way up to the most invasive. Again, it’s much easier on the plant (and you) to provide less water than to repot or transplant it. Try to save those options for last.
Continue testing the treatments you believe are most likely to fix the issue. Hopefully, one of them sticks.
Worst case scenario, start from step 1 and make a new list of possible issues. There’s a chance you might have missed something or notice something new the second time around.
Stay persistent! It’s easy to say, “Dumb plant, why don’t you want to live?”, but there’s always a reason why plants act the way they do. Stay the course and see if you can uncover it.
If you have no idea what issue your avocado tree might have, that’s okay! That’s what I’m here for. To give you a head start, let’s explore the 6 most common reasons avocado trees die.
The Top 6 Reasons Why Avocado Trees Die (& Fixes)
1. Under-Watering
When an avocado tree has too little or too much water for an extended period, the tree becomes stressed and shows signs of declining health. Common symptoms of under-watering are leaves curling, drying, browning, and dropping.
The best way to water avocado trees is to only water when the top 2-4 inches of soil is dry. You can check this by pushing a finger into the soil. The goal is to have soil moisture similar to a wrung-out sponge.
When watering, make sure to soak the soil down to at least 2 feet deep. The reason behind this is that 90% of the tree’s roots are found at this depth.
Deep watering also promotes deeper roots, allowing the tree to become more water independent in times of drought.
On the other hand, shallow roots are more common in trees that are water-pampered. They have a tougher time surviving when a watering session is missed or when the ground gets too hot for the shallow roots.
I also recommend providing the avocado tree with 2 inches of compost and 4-12 inches of mulch.
Compost provides valuable nutrients and increases the water retention of the soil. For example, every 1% increase in the soil’s richness (organic matter) leads to an additional 20,000 gallons of water held per acre (source).
Mulch drastically reduces evaporation, regulates soil temperature, and prevents soil erosion. As avocado trees evolved as understory species in forests, they became used to plenty of mulch in the form of fallen leaves and branches. As permaculture guru Geoff Lawton says, “A forest grows from a fallen forest.”
To recap, provide 2 inches of compost and 4-12 inches of mulch under the tree’s drip line or canopy. Reapply compost every 1-2 months and mulch every 3-6 months. Keep these materials at least 3 inches away from the tree’s trunk to prevent mold.
Compost and mulch are two of the most beneficial practices you can do for your avocado trees, and by only watering when the soil is dry, you’re dramatically reducing the likelihood your avocado tree gets under-watered.
However, what if you feel your avocado tree’s soil and it’s been sopping wet for days at a time?
2. Over-Watering
You can generally tell if your avocado tree is over-watered if it has yellow leaves, green leaves dropping, and root rot (more on this later).
While over-watering is possible in all soil types, it’s most common in poorly draining soils or those that are lower in the ground. This issue is compounded if the depressed soil is at the base of a hill and receives plenty of runoff.
Poor drainage is usually caused bycompacted soils or those withheavy clay content.Since clay particles are much smaller than sand or silt, they easily form a tight layer that allows little to no water to pass.
Another way of determining soil drainage is by doing a percolation test.
Here’s how to do one:
- Dig a 1-foot by 1-foot hole (outside of your tree’s drip line to avoid damaging its shallow roots)
- Place the yardstick in the hole and fill it with water
- Wait an hour and measure the rate that the water falls
The ideal rate of drainage is 2 inches per hour.
Naturally, if the percolation test is slower than 2 inches per hour the soil has poor drainage. Faster than 2 inches is fast drainage.
However, this is a guideline and not a rule, so don’t worry if yours is way off. The idea of this test is to quickly gauge if your soil’s drainage is poor or quick.
Pro-Tip: Perform multiple percolation tests in different areas to get a more complete picture of your overall property’s soil drainage.
What’s interesting is that poor-draining soils and fast-draining soils have the same solution—to increase the soil’s organic matter (AKA compost).
Organic matter not only breaks up the clumps of poorly draining soil but provides ideal water retention. It’s because of these effects that compost amends soils of all types and drainages.
In this case, I’d suggest applying 2 inches of compost every 1-2 months until the soil is amended. It can take some time, but the compost’s smaller particles work their way into the soil and break up the clumps over time.
The compost also encourages beneficial soil life such as earthworms to move in, which help aerate, stir, and further fertilize the soil.
You can also use gypsum to amend the soil’s drainage.
However, avoid using mulch until the soil has sufficient drainage. Mulch can make poor drainage worse by trapping the moisture between the ground and the mulch, preventing evaporation.
3. Excess Heat and Frost
Avocado trees do best in USDA hardiness zones 8-11, which are generally between 15ºF and 90ºF.
When avocado trees are consistently in temperatures of 90ºF and above, the tree’s leaves begin to overheat. Symptoms of this include leaves curling, drying, browning, and dropping (usually in that order).
If an avocado tree is already under-watered, any heat quickly compounds this, drying the tree extremely quickly. If this happens, avocado trees can die in a matter of days or hours.
Before looking at solutions, it’s helpful to know how avocado trees cool themselves.
Avocado trees stay cool by sending moisture from their roots to their leaves and through a process called transpiration.
Much like how humans breathe and release moisture when we exhale, plants do the same. Only, this is called transpiration. This increased moisture from plants is why a forest can feel more humid than its more open surroundings. And it’s extremely helpful for plants to stay cool and not dry out.
Now, looking at solutions, there are a few things we can do to adjust the tree’s microclimate and make it more comfortable during heat waves.
Tips for Hot Weather
- Compost and Mulch – as mentioned earlier, compost and mulch are incredibly effective practices for keeping avocado trees properly watered and cool. As long as the soil is staying moist and is not sopping wet, the tree can cool and support its leaves.
- Partial Shade – using other trees or structures to provide partial shade for avocados mimics their natural forest environment and gives them a break from the hot sun. Generally, it’s best to provide relief from thewesternsun as it’s the hottest. Even 2 hours of partial shade a day goes a long way.
- Dense Planting – by densely planting avocado with other plants, more roots hold groundwater, more canopies provide shade, and more leaves increase moisture through transpiration. So, not only does the ground stay cool and moist, but the air does as well! Densely planting different species also provides manycompanion plant benefits.
Tips for Cold Weather
While it’s a bit tougher to protect avocado trees against frost, it’s still possible. Here are some of the best ways.
- Mulch – aside from reducing evaporation, mulch is incredibly good at insulating the soil and regulating the avocado root’s temperature. Placing a 4-12 inch layer of mulch dramatically assists avocado trees with temperature control.
- Plant South – plant avocado trees on the south side of your property if possible as it provides the most sunlight and heat (north side if you’re in the southern hemisphere). You can also plant avocado trees along a south-facing wall to reflect and retain even more light and heat.
- Greenhouse – of course, if you live in zone 8 or colder, growing avocado trees in a greenhouse is a huge win. Similarly, you can grow dwarf avocado trees in pots and simply move them indoors during the winter.
To learn more about influencing your avocado tree’s microclimate, check out this cool video by Gardener Scott.
4. Improper Nutrients
Excess Nutrients
When avocado trees receive too many nutrients, their roots become chemically burned, stressing the tree and causing a decline in health. Excess nutrients are often caused by fast-release chemical fertilizers as compost isn’t potent enough.
If you believe you’ve over-fertilized your avocado tree, I suggest removing as much of the fertilizer as possible via leaching.
Leaching also works well if your avocado tree’s soil is high in salts, which is a fairly common issue and causes leaves to brown.
To leach, heavily water your avocado tree’s soil to dilute the existing fertilizer and allow it to flow deeper into the soil (and 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 avocado trees).
A 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 avocado tree in the past several months, there’s a good chance it may be dying from a lack of nutrients.
Symptoms of a lack of nutrients depend on the deficiency.
For example, avocado trees commonly get a nitrogen deficiency and get lightly colored or yellow leaves. This is more likely in younger avocado 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 avocado tree.
The Best Way To Fertilize Avocado Trees
If you decide to use a chemical fertilizer, opt for one with double the nitrogen to phosphorus and potassium (the three main plant nutrients, NPK), such as a 6-3-3. Each brand has different potencies, so follow the instructions on the label for the best results.
Alternatively, you can use compost. I recommend applying 2 inches of compost every 1-2 months under the tree’s drip line. Applying 4-12 inches of mulch on top of the compost goes a lot further and adds even more water retention and nutrients.
If you’d like to see which fertilizers I recommend, check out my recommended fertilizer page.
Keep in mind that while nutrients are essential, they aren’t everything.
Imbalanced Soil pH
Avocado trees prefer a soil pH of 5.0 to 7.0.
The reason avocado 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
When avocado trees have an imbalanced soil pH, they can develop issues such as discolored and dropping leaves. Additionally, their flowers and fruit drop early and the tree is more likely to develop other issues.
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 avocado 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 too acidic (under 5.0), provide alkaline amendments such as charcoal, wood ash, and lime.
5. Transplant Shock
If your avocado tree was recently planted or repotted, and it’s starting to die, 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.
Avoid transplanting avocado 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
6. Pests & Diseases
Western Avocado Leafroller (Amorbia)
Western Avocado Leafrollers are small caterpillars that are fairly common in California avocado orchards. They bind the plant’s leaves together to make a nest and can damage the tree, resulting in a great loss of fruit. Leafrollers also affect citrus trees.
Avoid using sprays as they typically damage the caterpillar’s predators and make the issue worse. Instead, encourage the caterpillar’s predators such as beneficial wasps and flies by planting companion plants, using pheromone baits, or ordering the wasps.
Monitor parasites and other natural enemies several times to determine if their numbers are increasing. If they are, the amorbia presence will decrease. Spraying with malathion often leads to outbreaks of other pests and is not recommended.
University of California Agriculture and Natural Resources
Root Rot
Root rot, also called Phytophthora Root & Crown Rot, is a root fungus that causes avocado 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 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!
Final Thoughts
While avocado trees die for many reasons, it turns out ours was declining from a lack of water and too much heat. After we put down a bag of each compost and mulch and provided partial afternoon shade, our tree started recovering.
If you think your avocado tree is declining from a pest or disease and you’d like to learn more, check out this helpful article by Plant Village, or this guide from the University of California Agriculture and Natural Resources.
