My parents have a few avocado trees, but one of them is dropping fruit early. While many of the dropped fruits are small, some are almost fully grown. They weren’t sure what was causing it, so I did some research to help them out. Here’s what I found.
Avocado trees drop their fruit early if the tree is either too young or too stressed. Typically, when avocado trees mature around 3+ years, fruit sets are more consistent and less likely to drop. However, stressors such as improper watering, root damage, and extreme temperatures lead to early fruit drop.
Generally, avocado trees drop some fruits that are defective or weak, as this doesn’t lead to good reproduction. This fruit drop event commonly occurs in June and is commonly called June drop. However, if your avocado tree is dropping many of its fruits prematurely, it’s likely due to age or stress.
First, let’s take a look at age.
Age
Depending on how you grew your avocado tree, it can take 3-15 years for it to mature enough to provide consistent and reliable fruits.
Generally, avocado trees that are purchased from a nursery are grafted, and mature in about 3-5 years, while those grown from seed can take up to 10-15 years.
In short, grafted trees fruit faster because they’re a clone of a mature tree. On the other hand, trees grown from seed have brand new DNA and need time to develop (just like children).
Because of this, avocado trees that have not yet matured may flower and fruit, but will likely drop them as the tree decides to grow its canopy or root system first. This is a good thing as a larger canopy will allow for more fruiting, while larger roots allow for better nutrient absorption, water intake, and anchoring.
So, if your avocado tree is grafted and under 3 years old, you may have to wait for the tree to mature before it develops its fruits and holds onto them better. If your avocado tree is grown from seed, and under 10 years old, you may have to wait longer for it to mature and fruit properly.
However, there’s always a risk that trees grown from seed might have inedible fruits or no fruits at all. Because of this, for the best chance of fruiting, purchase grafted avocado trees (grafted trees also have the same fruit as the tree it was cloned from, so there’s a high chance it’ll have edible fruits).
Generally, avocado trees that are purchased from nurseries are grafted, but you can always ask your seller to confirm.
Under or Over-Watering
Too little or too much water causes avocado trees to become stressed and drop their fruit as an attempt to shed parts of the tree that are draining resources. Flowers and leaves can also drop as a result. Generally, only water when the soil is dry and apply 2 inches of compost and 4 inches of mulch under the canopy.
The best way to tell if your avocado tree is under or over-watered is by the finger test.
Simply push a finger into the top 2-4 inches of soil. If it’s dry, water it. If it’s wet, hold off on watering until it’s dry.
While this is the golden rule of watering, it won’t work if the soil has poor drainage. Poor drainage is also the most common cause of over-watering. In this case, the soil should be amended for better drainage if possible.
You can check for poor drainage by seeing how quickly the water runs through the soil.
If you have a potted avocado tree, you can identify poor drainage if the soil still has surface water an hour after watering. Additionally, wet soil that’s left for too long starts to smell swampy. To fix poor drainage in potted trees, you can simply repot it with fresh soil.
If you have a planted avocado tree, poor drainage can be identified by digging a nearby 1-foot by 1-foot hole, filling it with water, and waiting for it to drain.
If the hole drains slower than 2 inches per hour, it has poor drainage.
Just make sure to dig the hole in a separate area of the garden (outside of the tree’s drip line) to prevent any shallow root damage (more on root damage later).
Unfortunately, it’s difficult to amend garden soil, especially if it’s heavy clay soil. Instead, amend the top of the soil by applying compost and mulch, which breaks down and works their way into the soil, amending it over time. Planting the tree in a mound also helps avoid issues with clay soil.
If not addressed, waterlogged soil begins to smell swampy, and leads to root rot. Over time, the tree begins to drop more leaves, flowers, and fruits, before dying.
The good news is that once your avocado tree’s soil is well-draining, it’s easy to maintain.
Once your avocado tree’s soil is well-draining, apply 2 inches of compost and 4 inches of mulch under the drip line of the tree.
Compost provides valuable nutrients and retains soil moisture, with every 1% increase in soil richness holding 20,000 more gallons of water per acre (source).
Mulch protects the soil from drying out in the sun and wind, helping shield the tree’s roots and beneficial soil life (like 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
Some good mulches for avocado trees are leaves, bark, pine needles, and straw.
Combined with the finger test, these two practices are incredibly helpful in simplifying watering and preventing both under and over-watering.
As a result, these practices work extremely well to help prevent fruit drop, among other issues.
Transplant Shock and Root Damage
If your avocado tree was recently transplanted or has shallow roots exposed, there’s a chance the tree is stressed, leading to issues such as early fruit drop. Generally, only transplant when necessary and provide mulch to help protect the tree’s shallow roots. Transplant shock can take up to one year for recovery.
Transplant shock typically occurs when the plant is exposed to a new environment and has to establish a new root system. This is common after avocado trees are moved to another area of the garden or are repotted.
After being transplanted, it can take some time for the tree to adjust and recover from the shock, especially if the roots were damaged. While recovery can take up to one year, if the damage is too great, the tree will likely decline in health before dying.
To help avoid transplant shock and root damage, I like to plant with the following steps in mind:
- Have the new ground (or pot) prepared
- Remove as much of the tree’s current topsoil as possible, without damaging the shallow roots
- Grab the base of the tree’s trunk and wiggle lightly
- Using your other hand, scoop up and support the rootball
- Lightly place the tree in the new ground (or pot) and fill it in
- Make sure the soil is at the same level on the trunk as before
- Apply 2 inches of compost and mulch to the top of the soil
- Water generously and add more soil as needed
Generally, as long as you avoid damaging and breaking the roots, and you keep your avocado tree comfortable during the move, the amount of stress from transplant shock will be reduced or eliminated.
To help avoid shallow roots from becoming exposed and damaged, apply 4 inches of mulch under the drip line of the tree. Mulching also has many other benefits (as mentioned in the watering section above).
However, avocado trees with bound roots can also become stressed and drop their fruit.
Root binding normally happens for potted avocado trees, but those that have too small of a root barrier can also be affected. You can tell if a potted avocado tree has bound roots if they’re starting to come through or circle the bottom of the pot (you may have to lift the tree out slightly to check).
To fix root binding, repot avocado trees into larger pots with fresh potting soil every 3-5 years.
Extreme Temperatures
Avocado trees are natively from the tropics, so they have little to no tolerance for frost. They can get stressed and drop their leaves, flowers, and fruit early either in cold weather (45ºF or below) or in hot and dry weather (above 100ºF). Generally, avocado trees do best in USDA hardiness zones 9-11.
If you’re growing avocado trees outside of these zones, or have an unusually hot or cold season, here are some climate tips that might help:
Cold Weather Tips
- Insulate the tree’s canopy with bedsheets or its trunk with cardboard. Provide windbreaks if possible.
- Plant avocado trees facing the south to get the maximum amount of sunlight and warmth. Planting along southern facing walls also helps.
- Apply mulch to help insulate the roots.
Hot Weather Tips
- Provide compost and mulch to prevent the soil from drying out and baking in the sun.
- Check the soil’s moisture often, especially on hot days. Water when it’s dry.
- If possible, shade the tree when temperatures exceed 100ºF or if you notice scorched leaves.
Keep in mind that moving avocado trees indoors can cause leaves to droop or fall off. This is either due to a sudden temperature swing (of 20ºF or more), or the central heat is drying out the leaves.
For example, last winter I moved my Meyer lemon tree inside and the central heat started stressing it out. Its leaves started to drop. I then moved the tree to a cooler room, without heat or fans (which can also dry out the air) and the tree’s leaves started growing back immediately.
If you’re interested in learning more about growing your plants in microclimates and stretching your hardiness zones, check out this cool video by Gardener Scott.
Final Thoughts
So, other than from June drop, avocado trees drop their fruit largely due to age and stress.
If your avocado tree is still young (under 3 years old if grafted, and under 10-15 years old if grown from seed) consider waiting a bit longer. If not, then stressors such as improper watering, transplant shock, and extreme climates all contribute to early fruit drop.
However, one stressor that I did not mention yet is a lack of nutrients. So, if you’ve checked the above list and aren’t any closer to helping your avocado tree overcome fruit drop, feel free to check out my other post: Avocado Tree Fertilizers: The Full Guide & Top 3 Brands.
