Why Are My Avocado Leaves Turning Brown?

Avocados are an exciting tree to grow since they are exotic and hold the promise of producing those oh-so-delicious fruits. They aren’t the easiest plant to grow or to get to bear fruits, however.

Avocado leaves turn brown because of underwatering, chemical build-up, nutritional deficiencies, rootbound plants, cold, pests/diseases, and overwatering.

Published: December 23, 2022.

You may be at the point where you are asking, Why do the leaves on my avocado plant keep dying? You are in the right place. Read on for the most common reasons for avocado leaves turning brown and the most common remedies.

Underwatering

Probably the most common reason for browning avocado leaves is underwatering. Avocado trees require a great deal of water since they use a lot of water for transpiration (cooling) in very hot weather, which can lead to the tree drying out.

If you are underwatering, you will notice your leaves start to droop. After that, if the plant is not watered, the leaves turn brown, curl up, dry out and then eventually fall.

If you see drooping, it is time to test your plant to see if it is dry. (Avocados may also droop due to overwatering, so don’t just water it if it is droopy. Check the moisture of the soil.)

Water your tree when the top three inches of soil are dry. Keep in mind you will probably have to water more frequently in the hot, sunny summer months and less in winter.

If your tree is in a very sunny spot, it will probably also need more water than a tree in the shade. This is why it is difficult to determine a schedule for watering. You will just need to monitor your specific plant to determine its water needs.

Chemical Build Up

The tips of avocado leaves may turn brown at the end of the growing season due to the concentration of chloride in the soil. The leaf tips will brown first, but then the leaves will turn completely brown and fall if the problem isn't addressed.

Chloride is present in a lot of water sources, though this problem may be especially acute in places that are fed by rivers that are very high in chloride (such as Southern California). If you don’t know whether this is a problem in your area, you can get a soil test from your local extension service.

The best way to remedy this problem is to soak your plants with water regularly to wash away the chloride that has built up in the soil. When you water, make sure you soak the plant completely to wash away any build-up. Do this at least twice a week during the late growing season.

Don’t water your plants just a little bit at a time. You will need to use a soak and drain method.

Make sure that you have very good drainage, so you don’t end up overwatering your plants.

Nutrients deficiency

You may be growing your tree in nutrient-poor soil, which could lead to a nutrient deficiency. Most commonly, this is zinc, iron, or nitrogen deficiency in avocados.

If your tree is over two years old, you can fertilize your avocado with an all-purpose fertilizer to remedy this problem and see if the leaf color improves. If you don’t want to use commercial fertilizer, try adding compost to your soil. Aim for soil being 10% compost or other organic matter.

Spring is the best time to fertilize avocados, although one can always dig in a little bit of compost or worm castings in the soil to improve the soil and to add some, but not too much, nutrients.

If the problem doesn’t improve with these remedies, you can get a soil test at your extension service that will tell you what nutrients are lacking.

Rootbound

If your avocado is potted, you may need to repot it in a larger pot. If you notice the roots making a ring around the bottom of the pot, then your plant needs more space! Roots need room to access nutrients and water from the soil.

A rule of thumb is to repot young avocado trees every 1-2 years. More mature trees can be repotted every three years.
Make sure you use a pot with drainage holes and add around 10% compost when repotting.

Cold Temperatures

Avocados don’t like frost or cold temps for long periods. If you have experienced a cold snap, and that is the cause of your brown leaves, then your leaves should improve when the cold has passed.

Typically a cold tree will have brown, mottled spots in the interior of the leaf. This is sometimes called “bronzing.” It looks like your tree has freckles. Once the cold has passed, the leaves may remain brown, but their health will improve, and new growth will be green.

However, if your tree is in a place where it is exposed to cold or frost regularly, it will need to be moved or protected if you notice the problem getting worse. You can use screens or covers to keep your tree warm when the temperature dips.

If your tree is indoors, make sure it is away from drafty windows where it might freeze.

A freezing tree’s leaves will look droopy, black or brown, and curled. This tree will need to be moved, or it will die.

Sun Scorch

Avocados can tolerate high sun and high temps, but young avocado trees can get sunburned. This is especially common when trees are moved from indoor or shady greenhouse spots to the outdoor sun too fast.

Sunburned leaves will turn yellow first and then will turn brown. This may occur in very high-altitude places or after a heat wave of several days over 100℉. Make sure your tree is adequately watered in a heat wave, and move potted plants out of the bright sun if the temperature is very high.

Fungus/Disease

Avocado trees are susceptible to fungal infections. If you notice brown spots or brown edges to your leaves, it may be a fungus. Not all avocado fungal infections should be treated with fungicides, however. You can find more information on fungal infections here.

Make sure you move any diseased plant away from all other plants.

Pests

You may have dry, brown spots due to the avocado lace bug, caterpillars, mites, or other pests.

The avocado lace bug will produce dry, brown spots that look like sunburn. This will be accompanied by black specks on the underside of the leaf.

Mites will leave tiny spots on the top and bottom of the leaf or along its veins. You might also see silvery webbing.

If leaves are curling on the ends, look inside. You might find a caterpillar.

The best way to avoid a pest problem is to keep your tree healthy, so it can fight off pests by itself. Keep it watered and fertilize it as needed.

Pesticide is not always the answer with avocados–since you might be killing off bugs that are natural predators of these pests.

If you have a tree that is very infected, it should be moved away from all other plants to avoid spreading.

Overwatering/Humidity

Overwatering is not typically a problem with avocados since they use up so much water, though if you live in a very humid climate, you may notice that your tree’s leaves are sparse, small, and pale. They may eventually develop brown spots or swollen veins.

This is due to the roots getting too much water. Waterlogged roots cannot adequately absorb nutrients, so your tree will not thrive.

Make sure your soil is not too compact or dense. It needs to have some aeration to dry out. Let it dry out until the top 3-4 inches are dry. Ensure that your tree has adequate drainage. If it is in a pot, make sure there are drainage holes, and it isn’t rootbound.

Should I Cut Off Brown Avocado Leaves?

If the leaves are totally brown, withered, and dry, then they are not contributing to the health of the plant. You can remove these leaves.

However, if the leaves are healthy but have been injured for some reason, such as by cold or by chloride, you can leave those leaves. They will eventually fall naturally as new growth fills in.

Other Tips for Growing Avocado Trees

If your tree is outdoors, you can mulch around it with a 6-inch layer of mulch. It’s a good idea to leave around a foot of space around the tree trunk for good drainage, but otherwise, mulch typically helps avocados thrive.

If you are growing your tree outdoors, make sure you choose a variety that can tolerate your climate zone. Some varieties are hardier than others.

Avocados need 6-8 hours of sunlight per day.

Conclusion

It can be very frustrating and anxiety-inducing when you notice your avocado leaves turning brown. Don’t panic, however. The most important thing is to get to know your tree.

You will need to monitor its conditions so you can identify the problem and find the solution. It may take a little while, but don’t give up! Be patient, and you will get your tree back on track.