When planting your coffee the last thing you expect is for them to be unhealthy; curling leaves are not a thrilling find, especially, when you diligently take care of your plant by watering, exposing it to the sun, and giving it the needed nutrients.
If you are looking for a solution to this problem, then you have hit the jackpot with this find because I intend to exhaustively tackle this topic to help you correctly tend to your plant.
Coffee leaves curl when they get too much or too little humidity, light, fertilizers, minerals, temperature, salts, and water. They also curl when the soil is not acidic and has high water retention.
I have compiled a number of reasons that may be making your coffee leaves curl and implementable solutions to reverse this problem; knowing all the possible issues helps you make informed decisions for your plant to thrive producing a bountiful harvest.
Causes of Coffee Plant Leaves Curling
There are a couple of reasons why coffee leaves curl.
When plants do not get enough water, they shed their leaves to prevent water loss through transpiration.
The leaves turn yellow and curl before falling off. The curling is also an adaptation plants use to preserve water.
Water your plant once a week to keep it from losing leaves; pour a third a cup of water at the base of your plant.
However, you must observe the soil. The soil should be moist, not wet and saturated when watering your plant. If it is dry, it means it lacks sufficient water.
The leaves are the best indicators of your plant needing water. Coffee leaves change when they lack moisture and water.
Watering the plants yields immediate results. You can tell just by looking at the plant if the solution is effective.
Overfeeding With Fertilizer
Too much fertilizer leads to chemical build-up in the soil, which interferes with water absorption; this intern causes the coffee plant foliage to turn yellow and curl.
It is important not to add fertilizer to your newly potted plant; wait until the roots of the plant are re-established.
It is also vital to use the specified concentration and portion of fertilizer in the stipulated frequency.
Fertilize your coffee plant once or twice a year. The best time to fertilize the coffee plant is summer and spring.
Ensure that your fertilizer has potassium, phosphate, and nitrogen because, after potassium, nitrogen and phosphate are the most important nutrients for your coffee plant.
Lack of Nutrition
Coffee leaves curl along the leaf margins when they lack sufficient nutrients. The leaves exhibit symptoms depending on the type of nutrient that is absent.
For example, if your plant lacks magnesium, the leaves appear greenish-yellow and curl upwards on the leaf margins.
Molybdenum deficiencies occur in middle and older leaves; the leaves curl upwards on the leaf edges.
For potassium, the leaves curl upwards along the margins accompanied by necrosis.
Check other accompanying symptoms to ascertain the type of nutrient your plant lacks and supplement the plant.
Coffee needs all the 16 plant nutrients to grow healthy. It gets part of these nutrients from the fertilizer.
The volcanic or loam soil also provides essential elements like iron, magnesium, calcium, potassium, and sodium. You can also boost the soil nutrients by adding compost.
Perform a soil analysis before making any changes to your soil and replenish it with the lacking nutrients.
If your soil is severely lacking in nutrients, replace it with soil that is rich in nutrients. Ensure that this soil has nitrogen, potassium, and phosphate.
There are different reasons behind the effect of temperature on leaf curling. For instance, it is the cold temperatures that stimulate leaf curling during winter.
Coffee leaves begin to curl at temperatures below 70°F (21.1°C); on the other hand, in summer, leaf curling occurs due to water stress.
During summer, the rate of evaporation from the leaves is higher than the rate of absorption from the roots.
In winter, freezing temperatures minimize the amount of water available for absorption. Both phenomena hinder the leaves from obtaining water.
Do not leave your plant outside during winter; a ten-minute exposure during winter is enough to kill the coffee tree because of frost.
During summer, do not let your potted plant stay in direct sunlight for more than three hours.
Coffee does not do well in extreme temperatures; therefore, always ensure the plant stays between 45°F (7°C) and 85°F (30°C).
Root Rot Due to Overwatering
Another problem that overwatering causes is root rot. Soil dampness because of too much water causes waterlogging at the roots; this interferes with aeration leading to root decay.
Root rot fungus, which thrives in moist soil also worsens the decaying process. Root root affects other physiological activities of the plant. As a result it shows yellowing of leaves, curling or even dropping of coffee leaves.
● Water your coffee plant daily; during warm and dry months, water your plant when the soil is two to three inches dry.
● In case the problem of oversaturation is due to poor soil drainage, change the soil in use.
● Treat the roots with a fungicide to prevent further rotting caused by root rot fungus.
Tap water contains minerals that build on the soil. Watering your plants increases the concentration of these salts in the soil.
The high mineral deposition hinders the absorption of water, which, in turn, causes leaf curling and burns the coffee leaves, making them brown.
Avoid getting high salt concentrations on the soil from tap water by using filtered water because it has no minerals or salts.
Having filtered water controls the amount and type of salts your coffee plant receives. It also improves the rate of water absorption.
Too Much or Too Little Light Exposure
Coffee is a warm-weather plant; it should get at least two hours of direct sunlight. The leaves do well in daylight temperatures ranging between 70° F (21.1°C) and 80°F (27°C). Too much direct light curls the leaves.
If possible, move your potted plant to an area where there is adequate sunlight during summer. Too little light exposure also causes leaves to curl; that is why many indoor plants have curling leaves. The solution is to place your plant where there is adequate sunlight.
Two diseases cause leaf curling on coffee plants.
● Coffee leaf rust is a fungal disease that attacks the leaf blade. The fungus causes the leaves to have spots that look like rust on metal; hence, the name. It also makes the leaves curl at the margin before they fall off.
● The coffee wilt disease is another fungal infection spread by the Gibeberalla Xylarioides fungus. The first symptom of this disease is leaf curling followed by necrosis, wilting, and eventual coffee plant death.
Since coffee leaf rust is a fungal disease, applying sulfur or copper-based fungicides controls the infection. Spray all affected roots to prevent the spread of the fungus on healthy leaves.
Additionally, fungus and pests move by wind, water, or human transfer. Minimize the spread of the disease by not touching contaminated leaves and reducing the transfer of the pathogen from contaminated clothing.
You can prevent the spread of the coffee wilt disease by clearing infected coffee trees.
Cut the infected tree from ground level and burn it to stop the infection from spreading.
Furthermore, restrict movement on the coffee plantation to curb the infection.
Common insects that attack coffee plants and cause leaf curling include;
● Spider mites – the bugs leave tiny white webs on the leaves.
● Mealy-bugs – attack the leaves and stems of the coffee tree. The insects multiply fast in dry weather. They appear as white clusters on the leaf and stem of the coffee plant.
● Coffee leaf miner bugs – attack leaf cells leading to necrosis. The action of the bugs on the leaf creates dark watery spots on the leaf blade and curling on the leaf margin.
Check your tree to see if you can spot tiny whitish-yellow insects or look out for webs. Spider mites leave cobwebs spanning the leaves; dust on leaves and fruits attracts these insects.
The situation is worsened during winter when there is little watering leaving the mites to lay their eggs all over the leaves.
● Eliminate spider mites using organic insecticides.
● Prune affected leaves and stem and throw them in trash bags. Putting contaminated plant parts in compost pits will multiply the bugs.
● If the population is high, use a pesticide with a short half-life to get rid of the mites.
● Introduce friendly insects like ladybugs to eat the spider mites.
As for the mealybugs,
● Introduce parasitic wasps to eat the insects.
● Apply neem, vegetable, or mineral oil on the plant to kill the mealybugs through suffocation.
● Spray the coffee plant with an insecticide to destroy the bugs.
● Take 70% or less rubbing alcohol (a mixture of isopropyl and water)dab it on a cotton swab and apply it to the areas infected with the bug.
For the coffee leaf miner,
● Spray a pesticide on the plant to destroy the bugs.
● Inspect the plant regularly for the pest after treatment
Coffee plants need high humidity for the leaves to remain healthy. The plant needs at least 30% humidity to reduce the rate of transpiration and keep the leaves from curling or twisting. Leaves curl to reduce evaporation on the leaf surface.
● Group your coffee plants to create a humid microclimate during transpiration. Keep the plants with similar humidity requirements together. Group the coffee plant with ferns, fiddle leaf figs, air, and tropical plants because they are high humidity plants.
● Use the pebble tray method to increase relative humidity for the plant. The pebble tray is a shallow dish filled with pebbles and water. Place the tray on your potted plant for a continuous humidity supply.
● Try misting in conjunction with grouping and the pebble tray. For misting, fine spray the coffee plant with water to increase humidity levels.
● You can also place your potted coffee plant in rooms that have the most humidity in your house.
Coffee Plant Curling After Repotting
Repotting may cause injuries on the coffee plant roots resulting in transplanting shock.
The injury on the roots causes poor water and mineral absorption, all of which make leaves curl.
Root injury also increases the likelihood of fungal infection on the roots because of water malabsorption in the soil.
Delay repotting as long as possible; wait for at least six to eight weeks of growth because the plant roots are still fragile.
If your plant is already injured, place it in a low lit area until it recovers. Low light reduces the activity of the plant, allowing it to rest and heal.
A coffee tree requires a third a cup of water; if the water is too much, the plant leaves begin to curl.
Too much water oversaturates the soil making it dumb; this causes root rot and attracts root fungus. You are not helping the plant by exposing it to too much water.
● Water your coffee trees once a week with a third cup of water for each tree. Adjust the watering routine accordingly as the seasons change.
● Ensure the plant stays in a humid place
● Check the soil of the plant for dryness, especially in hot and warm seasons. Water the plant if the soil is two to three inches dry.
Type of Soil
Coffee leaves curl when there is plenty of moisture, which comes as a result of the soil. The plant needs acidic soil that has good drainage properties. Soil that is permanently wet oversupplies moisture to the plant.
characteristics of coffee plant soil
● Sandy loam or volcanic red soil
● A pH of 6.0 or 6.5
● Compost as a mineral supplement
● Well draining
Replace your soil with an acidic soil that has a percentage of sand or coarse gravel to help with water drainage.
Do not use ordinary peat moss soils because they retain moisture and supply more water than your plant needs. Additionally, ensure the soil is wet but not soggy.
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Common Problems of Coffee Plant Leaves
● Brown spots on leaves – brown spots with a white center on the leaves due to fungal infection.
● Brown leaf tips – coffee leaves brown at the tips or edges when they lack moisture
● Yellow leaves – coffee leaves get an unattractive yellow color, a condition known as chlorosis, caused by basic soil (not acidic)
● Rust on leaves – patches of rust on the leaves caused by a fungus
● Dark watery spots – patches of the coffee leaves die because of an attack by the coffee leaf miners.
The leaves of your coffee plant are very telling of the condition of the tree. They curl when there is a problem with water and humidity supply, soil, temperature, and light. They also curl when the plant has a disease or has insects or pests infestation.
By examining your plant’s leaves along with other symptoms, you can deduce the plant’s problem and find the appropriate solution.
Part of taking care of your plant involves frequent inspections and implementing solutions to maintain the health of the plant. The results f your ard work will be coffee berries that make the tastiest beverage.