Lemon and citrus trees are some of the easiest and most common plants to put in the backyard. However, if the plants get neglected a common symptom is the lemon tree leaves yellowing.
Like all living things, citrus trees get sick too if they don’t receive the correct nutrients. And because citrus trees are quite ornamental, the symptoms clearly show in yellowing leaves, warts, fungal growth, and shedding.
The yellow leaves on citrus trees are an indication of chlorosis. The pallid coloring speaks of a deficiency in micronutrients. Likewise, the plant cannot produce enough chlorophyll for its green and healthy color.
Without chlorophyll, your plant cannot get energy from the sun and cannot produce carbohydrates. In short, the paleness is an apparition of your plant’s possible demise. And we don’t want that.
Prevention is better than cure. If you’re just planning to plant a citrus tree, make sure that you have the best environmental conditions – or simulate the ideal cradle for growth if your climate does not permit.
Citrus trees grow best in cool areas but need to be kept indoors for winter weather. Nevertheless, they can still grow in warmer climate. They require deep watering that would drain well.
Ideally, citrus plant fertilizers should have a 2:1:1 ratio of nitrogen, phosphorous, and potassium respectively. Practically, this means that you need to get a fertilizer with a higher nitrogen content.
Yellow leaves on citrus trees is your plant’s way of saying change your fertilizer. You can order citrus fertilizers online or you can always visit your local shop and check the contents yourself.
Depending on the discoloration, the treatment and management for chlorosis varies. If the yellow-leaves symptom is showing on your adolescent plant, here are some ways to address it:
Soil testing can ensure that plants grow on good soil. Soil with pH 6-8 is the most ideal type to grow citrus trees.
Citrus trees with lower pH get yellow leaves due to magnesium deficiency. With this acidity in the soil, you have to use 10L water with 2 tablespoons of Epsom salt (magnesium sulfate) to water the plant. Dolomite can also address this problem with acidity. However, if you used calcareous soil, foliar feeding may be necessary.
Alkaline soils have pH higher than six. This means that your plant is either deficient in iron or zinc. When leaves become pale but have darker veins, they lack iron; when leaves become yellowish and pointed at the top, zinc is lacking.
To address iron deficiency, apply chelated iron or use an iron fertilizer supplement. Meanwhile, spraying 2 tablespoons of zinc sulfate dissolved in 10L water can address zinc deficiency.
Nitrogen deficiency manifests in overall yellowing of leaves on citrus trees. The discoloration may be random as nitrogen is a mobile macronutrient. Usually, nitrogen transfers from old leaves to new ones to support new growth. As a result, older leaves tend to fall earlier and new ones tend to be more fragile than usual.
Nitrogen deficiency usually happens in the rainy season as water-logging is key culprit. This can easily be resolved in the dry season that comes afterward. However, it may also stem from constant over watering with highly-porous soil, compacted soil, or root rotting.
The practical way to resolve this is to give your plant just enough water and ensure that the soil fully absorbs the water. You can also resolve to spraying a low-biuret urea to the leaves to correct this.
Citrus plants require specific amounts of different micronutrients like magnesium, iron, zinc, manganese, and boron. Though they are susceptible to micronutrient starvation, excesses can also lead to toxicity.
Yellowing leaves accompanied by spotting is a sign of boron toxicity. To control the excessive boron levels in your plant, apply your nitrogen fertilizer as calcium nitrate.
Meanwhile, manganese toxicity manifests in bright yellow mottling, and sometimes tar spotting – brown scars on the leaves. You can lime the soil and repeat the process each year for up to four years to address this.
Citrus trees also cannot tolerate excessive salinity in soil. In particular, salt from manure or sodium chloride in soil or in water can turn citrus leaves yellow, create a burnt crust in the edges, and make the plant shed prematurely. If you live near the sea, you might have to think twice about growing lemon or grapefruit.
Watering a citrus tree is quite tricky depending on the climate as water tends to drain slower in colder seasons. The plant only requires infrequent deep watering, but how do you know if enough is enough? First off, know your soil. If your soil drains well then you don’t have to worry much, as long as you water it once it dries out completely. (In the summer, you can water once a week.)
The root of citrus trees is prone to root rotting or Phytophthora because some soil retain water for longer periods. Like chlorosis, root rotting also turns a citrus tree’s leaves yellow.
You have to ensure proper irrigation for your plant to avoid drowning it. The ideal water level for citrus trees is about two to three feet deep.
Autumn is the best season to plant citrus trees, while spring comes a close second. If you live in a tropical country or an area with warm climate, it is best to plant your citrus tree in a cool open area that receives plenty of sunlight.
Yellow leaves in citrus trees usually appear when temperature suddenly becomes warmer than usual. Yellow bleached out spots appear on the leaves seasonally especially in the summer. This indicates sunburn but easily resolves itself when the weather improves.
Meanwhile, put your plants indoors during extremely cold climate as citrus cannot withstand severe frosts.
The symptoms and remedy of ill citrus trees often overlap. Ultimately, fertilizer management can prevent or treat any problems that you have with your plant. The proper fertilizer with the magic 2:1:1 micronutrient ratio is your best bet to avoid chlorosis.
You might not be able to tell which micronutrient is the true culprit every time, but at least now you’re aware of your citrus trees signaling that they need more care.
We hope that this article has given an insight into why your citrus and lemon tree leaves yellowing and we have provided enough information so you can treat and prevent this from happening again.
I'm Ann Katelyn, Creator and Chief Author of Sumo Gardener. Since I was a child I've always been fascinated with plants and gardens, and as an adult this has developed into my most loved hobby. I have dedicated most of my life to gardening and started Sumo Gardener as a way to express my knowledge about gardening with the hope of helping other people's gardens thrive.
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