Magnesium deficiency manifests in lemon trees, most commonly by yellowing leaves. You can fix the problem and encourage healthy green leaves using Epsom salts made of magnesium sulfate.
Magnesium is integral to chlorophyll, making it crucial for photosynthesis and maintaining your lemon tree’s lush greenery. Mix one liter of water with two tablespoons (30g) of Epsom salts and apply directly to the soil around each lemon tree. You can also use it as a leaf spray in spring and summer.
- Importance of Magnesium for Lemon Trees
- Signs of Magnesium Deficiency in a Lemon Tree
- Causes of Magnesium Deficiency in Lemon Trees
- Will Epsom Salt Help With Yellowing Lemon Leaves?
- How Do You Apply Epsom Salt to Lemon Tree
- How Much Epsom Salt for a Lemon Tree?
- Can You Spray Epsom Salt On Citrus Trees?
Importance of Magnesium for Lemon Trees
A lemon tree relies on magnesium for numerous physiological processes throughout its existence. It offers your tree the following priceless benefits:
– Importance of Magnesium in Photosynthesis
Each chlorophyll molecule has a core of magnesium, an element. Because magnesium is needed to make chlorophyll, your lemon tree’s leaves are green. It also plays a vital role in the process of photosynthesis.
In particular, the magnesium in chlorophyll helps the leaf do its job of absorbing sunlight for photosynthesis. It is housed within chlorophyll enzymes, performing many more functions than just soaking up light.
Therefore, a lemon tree would be unable to produce enough energy to function correctly if magnesium weren’t present.
– Carbohydrate Metabolism
Meanwhile, on a more humorous note, lemon trees use magnesium to speed up their metabolism of sugars.
Enzymes involved in synthesizing and breaking down these necessary carbohydrates store them until they are needed.
In addition, magnesium plays a crucial role in the movement of sugars from the lemon tree’s leaves to its fruit and other tissues.
Magnesium is similarly vital for lemon trees because it aids cell membrane stabilization, affecting turgor pressure, leaf shape, and other factors.
– Magnesium Effects on Phosphorus Availability for Lemon Trees
Magnesium also acts as a phosphorus carrier in lemon trees, which is essential. More specifically, it promotes phosphorus uptake from the soil and movement to where it may be needed.
Phosphate metabolism is also greatly aided by this nutrient in citrus plants like lemon trees.
Phosphorus is necessary for the following:
- Growing healthy green leaves.
- Boosting fruit quality and yield, especially regarding improving sugar/acid ratio.
- Increasing fruit sets in lemon trees.
- Increased vegetative growth.
- Vegetative growth increased.
Since young lemon trees often have weaker root systems, phosphorus is essential. Therefore, a lack of phosphorus may result from a magnesium deficiency.
On the other hand, scientists in Egypt have found that orange trees produce more fruit.
– Protein Formation and Cell Division
Lemon trees from the ground up need magnesium. It helps activate various enzyme systems throughout your tree, plus it’s required for protein formation and cell division.
In saying so, the value of magnesium to lemon tree respiration and photosynthesis is absolute. Furthermore, optimizing magnesium levels has also been shown to boost the juice content of lemon tree fruits.
In short, chlorophyll cannot capture solar energy for photosynthesis without magnesium, and the plant cannot perform the critical metabolic functions related to carbohydrates and cell membrane stabilization.
Signs of Magnesium Deficiency in a Lemon Tree
 Yellowing Leaves
Magnesium deficiency is a common cause of leaf yellowing, which several other factors can also cause.
The main distinction is that yellowing leaves caused by a lack of magnesium result in yellow patches that start from the center of the leaves.
Because the veins usually stay green, this condition is called interveinal yellowing or chlorosis. Usually, the older and lower leaves are the first to die since the magnesium taken in is typically moved to the new growth.
A variety of other factors can also cause leaf yellowing:
- Overwatering or underwatering your lemon tree
- Transplant shock
- Poor aeration due to the soil being too compact
- Lemon tree diseases, such as citrus blight
- Deficiency of other elements, such as nitrogen
 Leaf Drop
The affected leaves will not only turn yellow between the veins but also die and fall off the tree in the long run. Again, leaf loss affects lower leaves and older leaves more than younger leaves.
 Poor Stem Growth and Fruiting
Your lemon tree will gradually slow in growth and lose its leaves. If the lemon tree produces any stems, they will be weaker and shorter.
The same holds for fruits, which will be reduced in quantity, size, and quality, and some flowers may even fail to develop into fruit altogether. After all, your tree’s magnesium deficiency is causing stress, and stress leads to lower fruit production.
 Increased Vulnerability to Pests and Diseases
Interestingly, some insects may be able to detect a chemical indicator released by a magnesium-deficient tree.
Therefore, it is unsurprising to find aphids, mealybugs, stink bugs, and other pests are bothering your sick lemon trees.
Your lemon tree will eventually stress and weaken from a lack of magnesium, leaving it more vulnerable to disease and pests.
Causes of Magnesium Deficiency in Lemon Trees
– Depletion of Magnesium in the Potting Soil
If your lemon tree isn’t getting enough magnesium from the soil, it probably doesn’t have enough magnesium to absorb. You may have been too lazy to repot your lemon tree every few years as you should.
Magnesium is stored in abundance in the seeds of lemon trees but is lost when the fruit is harvested or falls off. Due to the high energy requirements of fruit development, these trees use a lot of magnesium.
Magnesium is typically replenished via the breakdown and weathering of compound minerals. However, this is only sometimes the case because a potted lemon tree’s reserve is limited.
Therefore, if you don’t give your container lemon tree feed with magnesium, it will eventually become magnesium deficient.
Due to heavy irrigation and rainfall leaching, the soil may be low on magnesium for lemon trees planted outdoors.
– High Content of Competing Minerals in the Soil
Even if there’s enough magnesium in the soil, your lemons might not thrive. How so?
This is probably because magnesium’s absorption rate is decreased when it is present in a mineral environment with a higher concentration of other minerals.
Why? Because they are vying for the same pool of potential absorbers.
Your lemon tree’s soil probably has a high potassium concentration. By doing so, your tree will prioritize the uptake of potassium over magnesium.
Unfortunately, if you don’t correct the problem, your lemon tree will develop a magnesium deficiency.
Soil with a lot of calcium and ammonia can also make it hard for magnesium to dissolve.
– The Soil is Too Acidic
As a first step, any citrus grower should check the soil’s pH level; citrus trees thrive from 5.5 to 6.5. In a pH above 7.5, they will be unable to absorb certain nutrients, particularly iron.
Next, ensure you’re not planting near any concrete or other calcareous materials, as this is the only type of soil in which citrus trees can’t grow.
If your soil and/or water have a pH above 7.5, you can use chelated iron, but it is expensive.
Soil pH 5.5 to 6.5 is ideal for most lemon tree varieties. However, if the pH of the soil is too low, below 5.0, this makes most of the magnesium in the soil insoluble.
That means that magnesium won’t dissolve in water and can’t be absorbed well from the soil.
In other words, your lemon tree will eventually suffer from a magnesium deficiency due to the soil being too acidic. This is especially true during dry times or if you don’t water your tree as often as you should.
– Inefficient, Infrequent, or Wrong Fertilization
For varieties like the Meyer lemon tree, you must regularly use a slow-release general fertilizer or a high-nitrogen fertilizer.
You need to apply three times through the year, spaced out between spring and fall (aka the growing season). After that, there should be enough to keep your lemon tree healthy, productive, and happy.
Over time, your tree will deplete the soil of magnesium if you don’t apply a magnesium-containing fertilizer.
– Exposing your Lemon Tree to Long Spells of Cold, Wet Conditions
Magnesium deficiency in lemon trees is more common in cold and wet climates. This combination reduces root function and the amount of soluble magnesium in the soil.
– Damaged Root System
Shallow root systems may not reach areas of the soil where magnesium is available.
Transplanting also poses a risk to the root system. A lack of oxygen in the soil, fungus infection, root rot, compact soil, and poor drainage are potential causes.
– Sandy Soil
Magnesium deficiency is common in sandy and light soils. This is because these soils have fewer nutrients than nature. Furthermore, rainfall and watering can easily leach magnesium from sandy or light soils.
Will Epsom Salt Help With Yellowing Lemon Leaves?
A speedy “yes” sums up the situation nicely. Because it helps restore magnesium levels, applying Epsom salts to a lemon tree with yellowing leaves can be an effective short-term solution.
Epsom salt works best if a magnesium deficiency causes the yellowing leaves. Remember that other causes of this issue include lack of nitrogen, water, disease, and even excessive pest infestation.
In addition to eliminating yellowing leaves, the proper application of Epsom salts will also improve the productivity of your lemon tree and encourage the growth of lush green leaves.
Foliar sprays applied in the spring or summer can protect plants from interveinal yellowing throughout the growing season.
How Do You Apply Epsom Salt to Lemon Tree
Now that you know your lemon tree needs magnesium, you can get to work with some Epsom salt.
The three most common methods are watering, applying it straight to the soil, or putting it on the plant leaves.
Dosage changes are necessary if your lemon tree is an ornamental tree, a plant in a pot, or a mature tree in the garden.
Scenario #1 – Ornamental Lemon Tree
- Put together the things you’ll need – A watering can, stirrer, bucket, measuring tool, and high-quality Epsom salts (Amazon link).
- To make a gallon of Epsom salt water, combine two tablespoons of salt with ¼ gallon (1 liter) of water in a watering can or bucket. About 1 ounce of Epsom salt is needed for every decorative lemon tree.
- Dissolve the Epsom salts in the liquid by stirring.
- Use the Epsom salt solution to water your lemon tree. Make sure to get it down to the roots. Morning is the best time to water your lemon tree because the plant can absorb as much water as possible before the day gets too hot.
- You can put 1 ounce (30g) of Epsom salts directly into the soil. Then, after fertilizer has been applied, water it in thoroughly. Make sure to rinse any Epsom salts from the leaves.
Scenario #2 – Established Lemon Tree
- Use 1.25 tablespoons (20g) Epsom salts for each lemon tree.
- You can apply it directly to the soil or dissolve it in a liter of water in a watering can.
- Thoroughly water your lemon tree.
Scenario #3 – Container or Potted Lemon Tree
- Prepare one tablespoon (15 g) of Epsom salts for each lemon tree in a container.
- Mix at least a gallon of water with the Epsom salt in a watering can. Get the salts dissolved by vigorously stirring the mixture.
- You should give your lemon tree a good soaking until water begins to seep out of the bottom. Repeat the process once a month.
How Much Epsom Salt for a Lemon Tree?
The amount of Epsom salt you should use to treat yellowing lemon tree leaves depends on several factors:
- The height of your lemon tree – For example, one ¼ tablespoon ( 20g) of Epsom salt per 3.3 ft. (1m).
- The type of lemon tree – Dwarf lemon trees require less Epsom salts than standard or tall lemon trees.
- Similarly, ornamental specimens require approximately 1 ounce (30g) per tree, whereas each container lemon tree requires about one tablespoon (15g).
Can You Spray Epsom Salt On Citrus Trees?
Yes, you can spray Epsom Salt on Citrus trees, such as lemon, Key lime, oranges, etc.
For lemon trees, mix Epsom salt at one ¼ tablespoon (20g) per liter of water. That’s a third of an ounce per pint of water.
Put in a few drops of wetting agent or a mild liquid soap. This will reduce the likelihood of scorching and increase the distribution of Epsom salt across the leaf surfaces.
Spray your lemon tree 2-3 times every two weeks. If you want to keep the salt from burning the leaves, it’s best to do it when it’s cloudy or first thing in the morning.