A couple of readers asked me why their olive trees are getting brown leaves and brown-tipped leaves. While I had a good idea of what was causing it, I did some research to learn more. Here’s what I found.
Olive trees commonly get brown leaves from under-watering or hot weather. These create drought-stress and cause the leaves to begin to die, starting with browning and curling at the tips. To fix, water the tree when the top 2-4 inches of soil is dry. Also, apply 2 inches of compost and 4 inches of mulch.
So, while olive trees commonly get brown leaves from a lack of water, what are some other causes, and how can we fix them? Let’s take a closer look.
In this article:
- Improper Watering
- Weather Stress
- Transplant Shock
- Improper Nutrients
- Pests
- Diseases
1. Improper Watering
Compared to other fruit trees (such as apples, cherries, and peaches), olive trees are far less sensitive and require less care when watering and fertilizing.
“If olive trees are having problems, one of the last things likely to be causing it is a nutritional deficiency.”
Paul Vossen, Farm Advisor, University of California Cooperative Extension
But while olive trees can thrive with poor soil, they still grow best with regular watering. This is why the most common reasons olive trees get brown leaves are from under or over-watering.
The best way to water olive trees is to only water when the top 2-4 inches of soil gets 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.
This is called the “Finger Test” and it prevents both under and over-watering.
Under-Watering
While olive trees are natively from Mediterranean or dry climates and are highly drought-tolerant, they grow and fruit best when watered regularly.
You can tell if your olive tree is under-watered if you see the below symptoms:
- Yellow Leaves
- Curled Leaves
- Brown Leaves (or Browning at Tips)
- Dropping Leaves
- Soil Feels Bone Dry
Tip: A good way to tell if your olive tree is drought-stressed is if its leaves are turning brown at the tips. This indicates the leaves don’t have enough moisture and are dying from the tip first. These leaves may also curl.
When under-watered, olive trees can’t provide sufficient water to their leaves. The leaves then start to discolor, dry, and curl to conserve moisture.
If not watered soon, the leaves continue to dry until they turn brown and drop from the tree. Eventually, the olive tree dies.
You can tell if your olive tree is under-watered if the soil is bone dry. This happens much faster in hot weather (90ºF and above). For this reason, composting and mulching your olive trees are essential.
So, here’s how to fix under-watered olive trees:
- Water when the top 2-4 inches of soil is dry (water down to 2 feet as 90% of the roots grow here)
- Apply 2 inches of compost every 1-2 months
- Provide 4 inches of mulch every 3-6 months
Compost provides essential nutrients, increases water retention, and promotes healthy soil. For example, every 1% increase in the soil’s organic matter (compost) holds an additional 20,000 gallons of water per acre.
Mulch dramatically reduces evaporation, regulates soil temperature, and prevents soil erosion. It also provides extra nutrients and suppresses weed growth.
Tip: Once mature, olive trees require much less water and nutrients as their roots are deeper. It’s only in the first few years that olive trees need more regular care.
By following these three steps, you’re not only ensuring your olive tree gets the proper amount of water, but you boost its water retention. With this, you’re making your olive tree more drought-tolerant and reducing the amount of care you need to provide your tree.
But what happens if your olive tree’s soil stays sopping wet for more than 24 hours?
Over-Watering
| Causes of Over-Watering | Fixes |
|---|---|
| Watering too Frequently | Only water when the top 2-4 inches of soil is dry |
| Clay Soil | Amend with 2 inches of compost every 1-2 months |
| Poor Drainage | Apply compost or plant on a mound of soil |
| Watering During Rainstorms | Hold off on watering until the soil feels dry again |
Olive trees that have too much water, or “wet feet”, get issues such as poor aeration and even root rot (more about this later).
Here’s how to tell if your olive tree is over-watered:
- Yellow Leaves
- Dropping Leaves
- Sopping Wet Soil for Over 24 Hours
- Soil Smells Swampy
The best way to avoid over-watering is to only water when the top 2-4 inches of soil is dry. By checking the soil before watering, you significantly reduce the chance of over-watering.
However, if your olive tree’s soil is staying sopping wet for 1-2 days, it has a drainage issue and needs to be amended.
Poor Drainage
Poor drainage creates pools of water, which stresses the dry-loving olive trees. This causes their leaves to yellow, brown, and drop.
More specifically, the excess water blocks nutrients from being absorbed by the roots and leaches nutrients from the soil (diluting and pushing them too deep, out of reach of the tree’s roots).
Here’s how to fix olive trees with poor drainage:
- Check – See if the soil is staying sopping wet for 1-2 days. If it’s smelling like a swamp, root rot is likely setting in and you need to act quickly.
- Test – If you’re not sure about the drainage, you can also do a percolation test. To do this, dig a 1-foot by 1-foot hole, place a yardstick in, and fill it with water. Well-draining soil should be around 2 inches per hour.
- Amend – If you determine your olive tree’s soil has poor drainage, it needs to be amended. Potted olive trees should be repotted with fresh potting soil. Planted olive trees should have compost mixed into their soil. Compost not only retains the proper moisture but breaks up the larger clumps of soil.
Tip: Avoid mulching olive trees with poor drainage. In this case, it reduces evaporation and makes the drainage worse. Once the soil is well-draining, apply 4 inches of mulch every 3-6 months.
If you’d like more information about how to dry out wet soil, see my other post: The 7 Quickest Ways to Dry Out Garden Soil
2. Weather Stress
As olive trees are natively from Mediterranean climates, they prefer warm and dry (but not desert) weather. Because of this, they grow best in USDA Hardiness Zones 8-11.
Tip: If you live in the US, it’s helpful to know your USDA hardiness zone. Once you do, check the preferred zone of your variety of olive tree and see if it does well in your climate. This will help you plan and provide the right care for your olive tree (and other plants).
When olive trees are exposed to weather that’s too hot or cold, they get stressed and begin to show symptoms such as:
- Brown Leaves (or Browning at Tips)
- Wilting Leaves
- Dropped Leaves
Let’s take a look at how to care for olive trees based on your climate.
Tips for Hot Weather
If your olive tree is commonly exposed to temperatures 90ºF and above, it’s likely causing the brown leaves.
Before we jump into ways to cool your olive trees, it’s helpful to know how they cool themselves.
Olive trees (and other plants) cool themselves by:
- Sending moisture from their roots to their leaves
- Transpiring (exhaling moisture from their leaves)
Now that we know this, let’s use it to help cool our olive trees.
- Water – Water only when the soil is dry, but don’t let it get bone dry—especially in hot weather. Use the finger test and try to maintain the soil moisture similar to a wrung-out sponge.
- Shade – Provide at least 2 hours of afternoon shade (from the western sun). You can use umbrellas, other trees, structures, or shade sails. Don’t over-shade—give your olive tree at least 6 hours of daily sunlight.
- Compost – As mentioned, compost is great at retaining moisture in the soil. Apply 2 inches of compost every 1-2 months.
- Mulch – Follow up by putting 4 inches of mulch on top of the compost. Reapply the mulch every 3-6 months. Keep both the compost and mulch at least 3 inches from the trunk to prevent mold.
- Density – Using transpiration, planting your olive trees with other plants increases the humidity around them and keeps them cooler. A great way to do this is by growing olive tree companion plants.
Tips for Cold Weather
If your olive tree is frequently exposed to temperatures of 32ºF and below, it’s likely getting brown leaves from the cold.
Tip: Olive trees are evergreen, so they don’t drop their leaves in the fall and winter as deciduous fruit trees (such as apple, pear, and cherry).
If your olive tree is getting exposed to frost, here’s how to keep it warmer:
- Cover – Covering your olive tree’s canopy significantly reduces wind chill and provides a barrier to frost. Bedsheets are an affordable and common material to cover olive trees.
- Mulch – Insulate your olive tree’s soil with 4-12 inches of mulch. If you want, you can even add 2-4 feet of mulch. This helps prevent the ground (and roots) from freezing.
- Wrap – While the canopy and roots are protected, you can also protect and insulate the trunk by wrapping cardboard around it.
- South – If you live in the northern hemisphere, the southern sun is the hottest. So, if cold is a concern for your olive trees, plant on the south side of your property or plant along a south-facing wall to reflect heat onto the plant.
- Potted – Bring your potted olive tree inside if it gets too cold (typically under 32ºF). Keep the olive tree away from your central heater as it dries out the leaves quickly and causes more brown and dropped leaves (this happened to my potted Meyer lemon tree).
But what if you’ve been watering your olive tree properly and have had fair weather? What could be the issue then?
3. Transplant Shock
If your olive tree was recently planted or repotted, and it has brown leaves or is dying, 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 olive 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
If you haven’t planted your olive tree recently, let’s take a look at nutrients next.
4. Improper Nutrients
According to Paul Vossen, Farm Advisor for the University of California Cooperative Extension, the only common nutrient deficiency olive trees get is nitrogen. While potassium and boron deficiencies are possible, it’s highly uncommon.
| Nutrient Deficiency | Leaf Symptom |
|---|---|
| Nitrogen | Yellow Tinge and Poor Growth |
| Potassium | Light Green Leaves or Brown Tips |
| Boron | Small Leaves, Brown Tips, Short Branches |
It’s also possible the olive tree has a magnesium deficiency. This is normally seen by yellow leaves with green veins.
Olive trees are much tougher than other fruit trees (especially apples, pears, and peaches) and easily grow in poor and even rocky soil.
Because of this, nutrients are likely one of the last reasons olive trees get brown leaves.
However, providing your olive tree with decent soil and nutrients helps it grow and fruit better.
Also, a lack of nutrients is still possible for olive trees, and you’ll begin to see symptoms such as leaves curling, yellowing, browning, and dropping.
So, here’s how to fix olive trees with insufficient nutrients:
- Provide proper watering and drainage (promoting proper nutrient uptake)
- Apply 2 inches of compost every 1-2 months
- Provide fertilizer 1-2 times per year
Providing the proper drainage and watering allows olive trees to absorb sufficient nutrients from the soil, while compost and fertilizer replenish nutrients in the soil (and promote 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
To see the olive tree fertilizers I use and recommend, see my recommended fertilizer page.
Recommended: Are Epsom Salts Good For Fruit Trees? (The Surprising Truth)
Imbalanced pH
Olive trees do best with a soil pH between 5.0 and 8.5.
For context, most other fruit trees prefer a soil pH of 6.0-7.0, so olive trees are incredibly forgiving with soil quality and pH. However, your olive tree can start to have issues if its soil pH is below 5.0 or above 8.5.
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 olive tree’s soil is too alkaline (above 8.5) you can add acidic amendments such as coffee grounds, sand, and peat moss. On the other hand, if your olive tree’s soil is too acidic (below 5.0), add alkaline materials such as wood ash, charcoal, or lime (ground limestone).
Additionally, cold and/or wet soils are not good at promoting nutrient uptake as the olive tree will either be dormant during the cold or too stressed in wet soils.
5. Pests
Aphids
Aphids are small bugs that suck the sap from underneath the olive 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 olive 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 olive trees are:
- Spraying the leaves with a jet of water
- Spraying the leaves with neem oil (a natural insecticide)
- Encouraging 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 olive tree companion plants such as dill, fennel, and yarrow.
Spider Mites
Spider mites are similar to aphids, except they’re part of the spider family. They also feed on olive trees and cause stunted growth as well as leaves yellowing, browning, 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 olive trees such as the twigs and fruit.
So, if you see small dots on your olive trees, see if they’re depositing honeydew or webs and you’ll likely identify if they’re aphids or spider mites.
6. Diseases
Root Rot
You can typically tell if your olive tree has root rot if the soil is staying sopping wet for more than 1-2 days and starts smelling swampy. Allowing the soil to dry out or repotting olive trees with fresh potting soil are the best ways to amend this disease.
Root rot kills off the olive 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 olive tree.
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
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.
Peacock Spot
While the above conditions lead to brown leaves, if your olive tree’s leaves have yellow, brown, or black spots it’s likely peacock spot disease.
Peacock spot (Spilocaea oleaginea) is a fungal disease that causes olive tree leaves to get brown and black spots with yellow rings around the spots. After some time, the leaves drop from the tree. The tree’s flowers, fruit, and growth are also affected.
This disease is most common in the fall when it’s warm and wet, and is usually found in coastal climates.
Treatment typically involves a spray. To learn more about which sprays are recommended for peacock spot, contact your local cooperative extension office.
Alternatively, Stefan Sobkowiak – The Permaculture Orchard has a great video on a safe, homemade, and more importantly—effective fungicide (hint: the secret ingredient is whey). You can see his video below.
Need More Help?
You can always ask us here at Couch to Homestead, but you should know the other resources available to you! Here are the resources we recommend.
- Local Cooperative Extension Services: While we do our best with these articles, sometimes knowledge from a local expert is needed! The USDA partnered with Universities to create these free agriculture extension services. See your local services.
- 7 Easy Steps to Grow Fruit Trees (Free Guide): Need more fruit tree help from the ground up? See our free guide to make growing fruit trees a breeze.
- Ask the Free Community: Join The Couch to Homestead Community and connect with other members discussing gardening, homesteading, and permaculture.
- 30-Day Permaculture Food Forest Course: Learn how to turn your backyard into a thriving food forest in just 30 days with our online course.
Sources
- https://cesonoma.ucanr.edu/files/27175.pdf
- https://ipm.ucanr.edu/agriculture/olive/phytophthora-root-and-crown-rot/
- https://ipm.ucanr.edu/agriculture/olive/peacock-spot/