Last Updated on February 28, 2022 by Zachary Smith
Image: Jason Thien via Flickr / CC by SA 2.0
Are the leaves of your outdoor palm trees turning yellow or brown, and you’re not sure why?
You rely on your palm trees to bring beauty to your property, and watching them turn yellow is concerning. You’re worried that your trees might die or make the other trees on your property sick.
Fortunately, there are several remedies available to treat your sick palm tree.
At Zachary Smith Arboriculture, we treat yellowing California and Washington Fan Palms, as well as True Date Palms, in the San Francisco Bay Area each month with our tree health services.
In this blog, we’ll share our top tips for returning your palm trees to optimal health.
Let’s dive in.
Why is My Palm Tree Yellow? 4 Causes
Image: Jason Thien via Flickr / CC by SA 2.0
Palm trees are beautiful, resilient plants that are well-suited to hot, dry landscapes.
Still, diseases, improper planting conditions, and other factors can cause palm tree fronds to turn yellow or brown.
Here are the leading causes of discolored palm leaves:
1. Age
As palm trees mature, the old fronds turn yellow or brown and fall off. This is part of the tree’s natural pruning process. Usually, these fronds are the ones closest to the tree’s base. If most of the fronds are still green, this is nothing to worry about.
2. Insufficient Nutrients in the Soil
Palm trees need adequate nitrogen, phosphorus, and potassium to survive and thrive.
When palms don’t have access to these nutrients, you’ll see signs of nutrient deficiency in their leaves. Nutrient deficiencies are especially common in Majesty and Queen palms, which thrive in nutrient-dense soil.
The effects of nutrient deficiencies are as follows:
- A nitrogen deficiency may create yellow-green fronds.
- A potassium deficiency will cause yellow spotting on the leaves.
- A magnesium deficiency will cause the tips of the fronds to turn bright yellow.
- Unlike other nutrient deficiencies, phosphorus deficiency usually creates no easily recognizable leaf symptoms. Instead, phosphorus-deficient palms may be stunted and slow-growing, with short fronds and a distinct pyramid shape to the tree.
- A manganese deficiency can be fatal to palm trees. Common in soils with pH levels of 6.5 or higher, manganese deficiencies create yellowing between the veins of the leaves, or leaves that look withered, scorched, or smaller than usual.
- Boron deficiencies cause leaves to look small and shriveled.
3. Pests or Fungus
In some cases, pests or fungus can cause palm tree leaves to turn yellow.
Common palm tree pests and infections include the following:
- Leaf-spotting fungi.
- False smut caused by Graphiola species.
- Ganoderma Root & Bud Rot.
- Palm aphids.
- Mealybugs.
- And more.
While healthy palm trees are generally disease- and pest-resistant, infections can happen.
If you’ve ruled out other possible causes of yellow leaves and you’re in the San Francisco Bay Area, contact our team. We’ll inspect your palm trees for signs of disease or pest damage. If we find indications of either, we’ll recommend a treatment plan to restore your tree’s health.
4. Over- or Under-Watering
Different palm species have different watering requirements, with most requiring about 30-44 inches of water annually.
If you’re overwatering your palms, the leaves will turn yellow or brown and fall off before they die. If you’re under-watering, you’ll notice leaves that turn brown and crispy at the tips.
How do I Treat Yellow Leaves on my Palm Tree?
In some cases, yellow leaves don’t mean your palm tree is dying. In fact, many palm tree problems can be relatively easy to treat on your own.
If your palm tree has yellow leaves, follow these steps to resolve the issue:
- Start with a soil test. The most common cause of palm leaves turning yellow is inadequate soil composition. With this in mind, we recommend starting with a soil test. You can purchase a DIY soil test at your local garden center or hire our team to conduct one for you if you’re in the San Francisco Bay Area. The results will help you understand your soil composition, identify missing nutrients, and amend the soil as needed.
- Apply fertilizer. Depending on your soil test results, you may need to apply a slow-release, nutrient-rich fertilizer – especially if you have nutrient-hungry Queen or Majesty Palms on your property. Don’t just dump any fertilizer on your palm, though – contact our team for recommendations on which fertilizer to choose, when to apply it, and how much to use, based on the needs of your specific trees. We serve clients throughout the Bay Area and Central Coast. Once you’ve amended the soil, keep your trees on a regular fertilization schedule. We recommend fertilizing Queen and Majesty palms at least 3-4 times per year, while once a year may be sufficient for other varieties.
- Look for signs of pests or fungus. Drooping, withering leaves, root decay, and other signs of poor tree health could indicate a fungal infection. Webs, sticky film on palm fronds, or visible bugs on leaves, meanwhile, are all signs of a pest infestation. Because fungal and pest problems can be tough to treat on palm trees, we recommend working with a certified arborist like Zachary Smith Arboriculture to diagnose and resolve the issue.
- Make sure your tree is getting the right amount of moisture. Both over- and under-watering can cause significant problems for a palm tree. With this in mind, make sure you understand the moisture requirements for the type of palms on your property and the age of each tree (young trees require more water than older, established trees). If you’re not sure how much to water your tree and you’re in the San Francisco Bay Area, give our team a call. We’ll make irrigation recommendations that will help keep your trees healthy, strong, and disease resistant.
Should I cut off Yellow Palm Leaves?
As a rule – no.
Palm trees don’t generally require pruning. In fact, removing yellow fronds can worsen existing problems.
For example, if your tree is suffering from a nutrient deficiency, removing yellow fronds will cause the nutritional deficiency to migrate up the tree into new growth.
With this in mind, avoid cutting off yellow leaves. If you’re going to prune your palm tree, make sure you’re only cutting dead fronds (the ones that are entirely brown) at the tree’s base.
Can Brown Palm Leaves Turn Green Again?
Unfortunately, the answer is probably no.
While yellow leaves won’t generally turn green again, acting quickly can prevent additional yellowing on your tree.
Eventually, the yellow leaves will naturally turn brown and fall off, leaving room for plenty of new growth.
How Arborists Treat Yellowing Palm Leaves
When you hire an arborist to care for your yellowing palm tree, the team will follow these steps to diagnose and treat the tree’s condition:
1. Soil Testing
The first step in good palm tree care is always a soil test. A soil test allows the arborist to understand soil composition, amend the soil accordingly, and pinpoint nutrient deficiencies that could impact your tree’s health.
2. Soil Amendments
Based on the soil test results, an arborist will deliver targeted nutrients back to the soil around your palm tree. Usually, arborists will gradually introduce slow-release fertilizers and keep the tree on a regular fertilization schedule in the future.
We recommend applying a slow-release fertilizer at least once a year – generally in the early spring. Contact our team to learn more about the ideal fertilization schedule and formula for your palm trees.
3. Routine Trimming and Tree Care
Routine trimming of dead fronds makes room for new growth, while regular tree inspection allows the arborist to spot warning signs (like early indications of fungal infections or pest damage) and treat them before they do severe damage to your tree.
4. Treating Pests and Infections
One common fungal infection that affects palm trees is called Ganoderma root. This white-rot fungus degrades the woody tissue of a palm tree’s trunk and makes it harder for the tree to absorb water and nutrients. Infected trees exhibit signs like wilting and discolored leaves, slow growth, and more dead lower leaves than usual.
When it comes to pests, palm trees are susceptible to mealybugs, palm aphids, and more. Both of these pests cause damage to palm trees by feeding on palm leaves and causing leaf distortion, discoloration, and death.
Masses of mealybugs have a white, cottony appearance. Palm aphids, meanwhile, have oval, convex bodies that are dark brown. They like to hide in unopened fronds and may look like a scale on the foliage.
What Palm Trees Need to Grow & Thrive
Palm trees are resilient plants that usually require minimal maintenance. All types of palms, including the Majesty Palm, Areca Palm, and Sago Palm, need just a few basic things: plenty of water, adequate light, good soil, and occasional trimming.
Here’s a breakdown of each:
1. Water
Newly planted palm trees should be watered at least twice a week until the plant is established, which can take about 2-3 months. Once the tree is settled, palms are quite drought-tolerant and rarely need to be watered.
2. Light
Most palms grow in full sun, but some species can tolerate a bit of shade. Palms that don’t get adequate light may grow slowly or develop health problems.
3. Nutrients
Palm trees, like all plants, need nutrients to grow and thrive. Palms planted in good soil can draw most of those nutrients from the ground around their roots. Still, we recommend applying a good-quality slow-release fertilizer in the early spring. More on this later.
4. Trimming
Generally, palm trees don’t require annual trimming. We do recommend removing dead fronds, though. If you notice a dried-out, brown frond on your tree, trim it to make room for new growth.
How do you Keep Palm Trees Healthy?
Photo: Rictor Norton via Flickr / SA 2.0
It’s easier to keep palm trees healthy from the start than it is to restore a sick or dying palm.
Follow these tips to keep your outdoor palm trees strong, resilient, and beautiful:
- Prune sparingly. We can’t say it enough: palm trees, unlike other outdoor trees and plants, don’t require regular pruning. Palms get most of their nutrients through their leaves. Removing palm fronds unnecessarily can cause malnutrition or leave the tree vulnerable to pests, disease, and damage from the elements. If you’re going to prune your palm, make sure you’re only removing dead fronds that are entirely brown.
- Be careful how you plant new palms. When introducing new palms to your landscaping, ensure you’re planting them correctly. Never put fertilizer down before placing your palm in a new location since this can burn the delicate new root system. Instead, plant the palm in a 50/50 mixture of native soil and sand and let the tree settle for 3-4 weeks before applying any fertilizer.
- Provide special care while palms get established. If you’ve purchased your palms from a greenhouse or transplanted them from a different area of your property, pay special attention to them for the first few months. Palms transplanted from shady areas may need screening to protect them from sunburn, and all newly planted palms will need to be watered heavily at least once a day for the first few weeks.
- Apply fertilizer correctly. When it’s finally time to fertilize your new palm trees, make sure you apply the fertilizer correctly. For best results, keep fertilizer at least two feet from the trunk of the trees, which will prevent burns to the palm.
Are your Francisco Bay Area Palm Trees Turning Yellow? We Can Help!
You don’t have to live with sick, yellowing palm trees.
Here at Zachary Smith Arboriculture, our team of arborists helps keep palm trees healthy on residential and commercial properties in Northern California – from Marin to Monterey.
If you’ve noticed signs of yellowing or discoloration in your palm tree leaves, we can help. We’ll carefully inspect your trees and soil to identify the problem and create an action plan to resolve it.
Contact us today to learn more about our services or book your consultation.
