Palm trees can suffer from nutritional deficiencies of important elements like potassium (K), nitrogen (N), manganese (Mn) and magnesium (Mg).
Other less common deficiencies of calcium (Ca), boron (B), zinc (Zn), and copper (Cu) deficiency can also be found. Nutrient deficiencies can be caused by poor soil, insufficient fertilization, incorrect planting depth, high soil pH, and poor soil aeration.
Some nutritional problems are very hard to diagnose because symptoms of different deficiencies may overlap ( in some palm species more than others). For example, late-stage K and Mn deficiencies, which appear as frizzled and reduced in size new growth, are easily confused on royal and queen palms.
Symptoms of Fe and K deficiencies can look very similar in royal palms while Mg and potassium imbalance are very similar in pygmy date palms. In any case, I always recommend establishing a regular fertilizing schedule and using slow-release good quality fertilizer.
1. Palm Tree Potassium (K) Deficiency
Palm trees need potassium in large amounts. Potassium deficiency is most common in Florida and in coastal South Carolina where soils are sandy and naturally deficient in potassium.
Potassium affects older fronds first and then progresses to the newer leaves as the problem becomes more severe. Early symptoms are translucent yellow to orange spots that sometimes are accompanied by black spots of dead tissue.
Dead tissue areas can also appear along the margins. On some palms, dead tissue along the margins is the first sign of potassium deficient. As the problem worsens, the entire leaf starting to look burn, wilted and frizzled.
You can see an example on the photo above. The bottom leaves of the Ruffled fan palm starting to develop necrosis (dead tissue) along the margins as a result of potassium imbalance.
After all of the potassium has been moved from the older fronds to the new ones, the palm declines. In severe cases the new emerging fronds are small, and frizzled. Additionally the trunk gets narrower towards the crown of the palm creating so called ‘Pencil-pointing’ look. Without immediate fertilization treatment the palm tree will die.
The most susceptible to potassium deficiency palms are: coconut, areca, spindle, queen and royal palms.
One of the common reasons a palm can become potassium deficient is because many gardeners use the same turfgrass fertilizer for the palm as well as the lawn. Fertilizers for the lawn are high in nitrogen but low in potassium.
You can fix potassium deficiency by applying slow release potash with magnesium. Magnesium is needed to prevent magnesium deficiency which could happen because of the additional potassium.
Keep in mind, fertilizer sprays with potassium are ineffective because of the small amount of K comparing the about needed to correct the problem.
It may take a palm up to two years to recover completely from potassium deficiency because it has to produce new fronds to replace all the affected ones.
Pictures Of Palms With Potassium (K) Deficiency
2. Palm Tree Magnesium (Mg) Deficiency
Magnesium deficiency is very common in Florida and other areas with poor soil. Sandy soils coupled with heavy rainfall results in quick leaching of this important element. While this type of deficiency is not fatal, it does effect the look of the palm.
Main symptom is a broad light yellow band along the margin of the leaves with green center. The yellowing starts on older leaves and progresses upward to the youngest fronds.
In sever cases, the leaflet tips turn brown as a result of dying tissue. As with other deficiencies, damaged foliage will never turn green again and needs to be replaced by the new healthy leaves. Date palm is one of the most susceptible to Mg deficiency.
Here is a severe Mg deficinecy on Sylvester Date Palm (Phoenix sylvestris). Almost the whole crown is yellow with necrotic leaflet tips on older fronds.
It might take years for the palm to recover from Magnesium deficiency so it’s best to prevent it from happening. Apply 2-4 pounds of magnesium sulfate (epsom salt) per tree 4 times a year to fix the problem.
Prilled kieserite (a more slowly soluble form of magnesium sulfate than Epsom salts) is an excellent slow-release and low-cost source of Mg.
Pictures Of Palms With Magnesium (Mg) Deficiency
3. Palm Tree Maganese (Mn) Deficiency
Manganese deficiency also called ‘frizzletop’ can be fatal to palm trees if left untreated. It shows up on acid-loving palms grown in alkaline soils. This problem is caused by insufficient Mn in the soil or by high pH (above pH 6.5). Other factors like poor drainage or too much water can also play a role.
Mn deficiency can also be caused by cold temperatures that reduce root activity levels in Mn marginally sufficient soils. Symptoms appear only on new growth which emerge deformed, reduced in size, with dead brown areas.
As the condition worsens, only dead leaf stems will emerge followed by death of the bud. If the bud of the palm dies, the palm will not survive.
Avoid planting acid-loving palms in alkaline soil. To correct Mn problem, apply manganese sulfate to the soil or spray it on the foliage. The most susceptible to Mn deficiency palms are Pygmy date, royal, queen, and paurotis palms.
4. Palm Tree Nitrogen (N) Deficiency
Nitrogen deficiency is not a big problem for palms. It’s usually seen only in areas with poor soil and lack of additional fertilization. Symptoms of nitrogen deficiency are overall light green color of the leaves and decreased growth of the palm.
It starts with the oldest fronds and progresses to the new growth as the nitrogen gets moved from older leaves to the new ones.
If left untreated, the entire canopy can turn yellow-green with some leaves turning nearly white. As the growth declines and slows down, trunk might get smaller in diameter closer to the top of the palm developing ‘pencil-pointing’ look.
Apply any slow-release fertilizer containing N to correct the issue. You can also treat the foliage with liquid fertilizer spray which should quickly improve the color of the leaves.
Pictures Of Palms With Nitrogen (N) Deficiency
5. Palm Tree Iron (Fe) Deficiency
Iron deficiency is generally uncommon in palms and is most likely a result of poorly aerated soil, root damage, or improper planting depth rather than lack of Fe in the soil. Poor drainage or water logged soil, suffocate the roots of deep planted palm.
You can recognize Fe deficiency by yellow-green fronds with green veining, usually seen on newest leaves first. As the problem worsens, new growth will become reduced in size and show extensive dead tissues at the tips.
While this is primarily a cosmetic problem and palms can exist with it for a long time, the growth of the palm will be stunted if left untreated. In cases with water logged soil, root rot might develop killing the palm.
Iron fertilization might temporarily improve the issue, but the problem will remain until planting depth or the soil aeration is corrected. There are many options to add Iron to the soil.
The most efficient treatment is chelated Iron which consists of organic elements that bind the iron like a claw making it available to the plant.
EDDHA iron chelates is the best chelate for release of iron over the highest pH limit. You can also use iron sulfate foliar spray to improve Fe deficiency.
Pictures Of Palms With Iron (Fe) Deficiency
Palms With Overlapping Nutrient Deficiencies
As I’ve mentioned above, sometimes deficiencies can overlap. Here are pictures of palm trees with an overlapping deficiencies of Magnesium (Mg) and Potassium (K).
You can see marginal yellowing in addition to brown tips and yellow flecks on leaflets on the older fronds of Pygmy Date Palm Trees (Phoenix roebelenii).
Here is a Fiji fan palm with overlapping deficiencies of Magnesium (Mg) and Potassium (K). You can see evidence of Mg deficiency on older lower leaves that have yellowish-orange leaf tips. In addition, there is a Potassium (K) deficiency that shows as leaf tip necrosis (dead tissue) and yellow flecking.
Here is more information on palm nutrient deficiencies on idtools site.
How Often Do I Need To Fertilize a Palm Tree
Your fertilization schedule should depend on the amount of rains you get and on the soil type. Sandy soils and heavy rains, leach nutrients from the soil very quickly. So you would need to fertilizer your palm about 3-4 times a year to keep balanced nutrient levels.
If you live in an area with lower rainfalls and better quality soil, then fertilizing 2-3 times a year should be oi. The fertilizer quality also matters a lot. Slow-release formula provides continues fertilization over a period of a few months.
What Is The Best Palm Tree Fertilizer
I always recommend using good quality slow-realease fertilizer that has continuous release formula. It will keep feeding your palm for a few months rather than being washed away after couple of rains.
While there are a lot of different palm fertilizers on the market, I prefer using those that have formula with same amount of Nitrogen (N) and Potassium (K). So fertilizers with NPK (Nitrogen, Phosphate, and Potassium) ratio of 12-4-12 or 15-5-15 or 3-1-2 are a good choice.
Jobe’s Palm Fertilizer Spikes
One of the top fertilizers that I use is Jobe’s Palm Fertilizer. It has a slow release formula with NPK 10-5-10 that is design to effectively fertilize your palms while protecting them from common deficiencies of Magnesium, Potassium, Manganese, and Iron. There is also spikes for indoor palms.
Jobe’s Organics Fertilizer
If you have pets and kids and prefer an organic fertilizer, try Jobe’s Organics. It has received over 4,000 five star reviews on Amazon, and is considered the best on the market by many gardeners. It’s formula of NPK of 4-2-4 is perfect for palms.