Growing indoor plants is an excellent idea as it gives your interior an evergreen look. But growing indoor plants has its challenges, yellow leaves being a widespread problem. It indicates that your plant is facing some challenges.
But what causes yellow leaves in indoor plants and how can you fix them?
The primary causes of yellow leaves in indoor plants are watering issues, inadequate light, nutrition imbalance, over-fertilization, humidity issues, or pest and fungus infestation. Apart from those, sometimes the leaves start turning yellow naturally because of aging in the plant.
If you are planning to grow houseplants, you should know the common causes of yellow leaves to prepare yourself for treating them if yellowing happens.
This article will help you as we have compiled a list of some possible reasons for fixing yellow leaves in indoor plants.
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Types of yellowing
The yellowing of leaves occurs in different types and areas.
Yellow lower leaves: This happens when the roots come out of the pots and need more space for growth, or the plant has low nitrogen or needs bright light.
Yellow leaves at the end of the stems: This happens when the houseplant has iron deficiency. Plants need nutrients to remain healthy. The deficiency of any one nutrient will make the plant act negatively.
Yellow leaves near the main stalk appear when your plant is suffering from magnesium or zinc deficiency.
When all the leaves start turning yellow slowly, the probable causes are overwatering, pests or diseases, excessive light, or the soil has lost its acidity.
Yellow leaf edge occurs with the old leaves: This is an entirely natural and expected part of the aging process in all plants.
When yellow leaves occur with black spots, the reason probably is some bacterial or fungal infection.
Yellow patches at the middle of the leaf blade appear because of nutrient deficiency. Besides the three essential nutrients, they also need other minor nutrients like calcium, magnesium, iron, and sulfur.
Causes of yellow leaves in the indoor plants
It is frustrating when our lovely houseplants start losing their charm due to yellow leaves. It is more frustrating to remain unknown to the real reasons behind this problem.
There are a lot of reasons behind the leaves turning yellow. But, you can identify the actual causes by noticing the yellowing pattern.
One apparent reason for yellow leaves is poor lighting. Both low and excessive light will result in yellow leaves on your houseplants.
Too much light increases the transpiration rate of the plants. This causes dehydration, resulting in yellow leaves. Moreover, the leaves curl, droop and become dry and crispy around the tips and edges.
It is better to keep the plant a few feet away from the window. This will provide them with the perfect amount of light. In some instances, you can also pull down the curtains to create filters for direct sunlight.
Every plant needs light to produce energy through photosynthesis. Lack of light will not support the production of chlorophyll. Therefore, the leaves will start turning yellow. The plants will begin curling upwards and become leggy as they constantly try to reach for the light.
Although some plants can grow in low lights, too low light will harm their growth.
Try to keep your indoor plant in a spot where it will receive bright indirect sunlight. If your houseplant needs more sunlight, place them near a south or west-facing window.
Indoor plants like cactus, succulents, or herbs can tolerate direct sunlight.
If your indoor plant prefers indirect sunlight, pull down curtains to create a filter and keep them in front of a north or east-facing window if possible.
Plants like Peace Lily, Snake plant, Pothos, or Philodendron prefer indirect light and can survive in low light also.
To protect your indoor plants from direct sunlight, keep them in a semi-shaded spot. During the night, bring them inside the rooms to protect them from cold drafts.
There are three types of issues related to watering – overwatering, underwatering, and poor water quality.
Overwatering is a common reason behind yellow leaves. The initial sign of overwatering is lower leaves turning yellow. But when the problem increases, all the leaves turn yellow.
We sometimes get confused about how much and how often we should water our indoor plants. Some houseplants need frequent watering, whereas some houseplants grow just fine with infrequent watering.
However, you should know that most houseplants do well when watered every 1 to 3 weeks.
Overwatering can also occur due to a poor drainage system. The soil and the pot must have a sound drainage system to drain the excess water. The pot’s size will depend on the plant’s size. An oversized pot can also cause overwatering.
In severe conditions, overwatering will result in root rot. The roots will change their color, feel damp and mushy, and the potting soil will also release a foul smell. In such conditions, you will have to repot the plant with fresh soil in a new pot.
Underwatering can also cause yellow leaves in houseplants. The lower leaves start becoming yellow, droopy, dry, and brittle when touched. Ultimately the leaves start falling off the plant.
Some plants even show signs when they need water, much before turning yellow. Water the plants thoroughly and allow the excess water to drain from the pot. Make sure the pot has drainage holes.
Underwatering causes less harm than overwatering. But both cause yellow leaves and, in severe cases, damages the plant’s health.
The factors upon which the watering depends are the size of the plant, pot type and size, seasons, temperature, and humidity. For example, big plants need more water than smaller ones, high-temperature demand more watering than low temperatures, etc.
Different plants have different watering needs. So, water the plants according to their individual needs along with keeping these factors in mind.
Also read: Overwatering Vs Underwatering Plants
Some types of water are harmful to various houseplants. Tap water, especially, causes more harm. It contains chlorine, fluorine, chloramines, bicarbonates, and other hard minerals, which cause yellow leaves.
However, some houseplants can tolerate tap water, but plants like Peace Lily, Dracaenas, and many others are sensitive to tap water minerals.
You can try using tap water. But if your plant is reacting negatively, you will have to change the water. You can use distilled water or collected rainwater. You can also get spring water from the market.
You can use the tap water by filtering it. If there is no way of filtering in your home, you can allow the water to sit overnight. Use it the next day. Allowing the water to sit overnight will let the minerals evaporate.
Still, if your plant is showing yellow color in the leaves, there must be another problem.
Nutritious and suitable soil is an indispensable requirement for a healthy plant. Poor soil quality leads to problems like overwatering, underwatering, and incorrect pH levels.
If the soil has poor drainage, it will develop watering-related problems. You must prepare the soil to drain excess water and retain enough moisture for the plant.
If the soil fails to drain excess water, the soil will get soggy, which will result in yellow leaves. Similarly, if the soil cannot hold enough moisture, it will make the plant stand in drought, which will also cause yellow leaves.
It is better to avoid clay and sandy soil. The former holds water for a long time, and the latter drains water too quickly, without giving the plant the chance to absorb water and nutrients.
If the soil mix has one of these two kinds, adding compost will solve the problem for both. An ideal soil mix for indoor plants would be a combination of perlite, vermiculite, and peat moss.
The plant generates yellow leaves when the pH level of the soil drops or increases. Some plants like marigold and monster plants prefer low acidic soil, whereas Yucca, Rubber plants, and Rhododendrons prefer acidic soil.
The nutrients already present in the soil work well for the plants. But, with each watering, the nutrients get washed away. That is the reason why fertilizing is essential.
If you do not fertilize your plant, it will show signs like yellow leaves due to poor nutrition.
Along with the three essential nutrients, nitrogen, phosphorous, and potassium, other micronutrients like magnesium, sulfur, iron, and others are also needed. Different deficiencies cause different yellowing:
Nitrogen deficiency will lead to yellowing of the older leaves, starting from the inner side and slowly progressing to the outer side.
Potassium deficiency causes yellowing of the edges in the older leaves. The inside part stays intact.
Magnesium deficiency results in yellow blotches between the veins in the old leaves. Slowly the edges start yellowing too.
Iron deficiency causes yellowing in the middle of the leaf veins of the younger leaves.
Sulfur deficiency results in the yellowing of the new leaves.
So, fertilizing is essential for indoor plants to keep them healthy, appealing, and filled with blooms.
A balanced fertilizer will be great for indoor plants. You can also use fertilizers high in nitrogen for more growth or high in phosphorous to promote abundant blooms.
Sometimes, the fertilizer varies from plant to plant according to their needs. It is better to fertilize your plant once a month during its growing and blooming seasons.
Do not over-fertilize your houseplants, as that can be more harmful than under-fertilizing. Over-fertilization resulting in the accumulation of salts in the soil, causes yellow leaves.
Stop fertilizing if your plant is showing yellow leaves due to over-fertilizing. You need to flush the soil to get rid of the salts.
Exposure to the wrong temperature
Another common cause of yellow leaves is exposing the houseplants to the wrong temperature. Either they are getting too high or too low temperatures.
Most houseplants grow best in temperatures from 60-80°F. Their temperature preference is one reason these plants are grown as houseplants. They will be able to tolerate room temperatures only, the one that is comfortable for humans.
You should keep your houseplants away from heaters, radiators, or air conditioners. Excessive hot and cold drafts coming out from them will affect the plants and result in yellow leaves. Along with that, the dry air will decrease their humidity level.
Please keep them in a room where the temperature is average. Place them some feet away from the windows and doors.
The constant opening and closing of doors and windows cause rapid temperature change. This might stress the plants causing yellow leaves within few days. Move the plants away from such spots.
Before buying the plant, analyze the temperature while traveling back home. The plant might not react positively if it faces temperature stress while traveling from shop to house.
A lot of houseplants belong to tropical areas where they thrive in high humidity levels. In our houses, it is not possible to mimic such high humidity. But we should try to provide them with at least some of it.
Low humidity results in yellow leaves and browning at the tips and edges.
To maintain humidity, you can mist the plants regularly. You can also keep your houseplants on a pebble tray with water. But the pot should not touch the water.
If your room has a lot of tropical houseplants, humidifiers are the best choice. It will mimic the right humidity level for the houseplants. One device will work for all.
When the plants overgrow, the roots need more space. In such conditions, repotting becomes necessary. If you keep the plant in such a condition for a long time, it will become rootbound. The roots will fail to get oxygen, suffocate, and will not absorb water and nutrients.
Finally, due to all these things, the plant will start showing yellow leaves.
Another reason is root rot due to overwatering. Due to such unhealthy roots, the plant will not consume water and nutrients, resulting in yellow leaves.
The best solution for both is repotting. Use a pot slightly bigger than the existing pot. It will make enough room for root growth. For root rot solution, use a new pot and fresh soil as the old one might get affected by bacteria and fungus.
Also read: How Do I Know If My Plant Needs Repotting?
Sudden transplantation of the indoor plants gives an entirely new environment to the plant. A sudden change can stress the plant.
If you have recently transplanted your houseplant and find yellow leaves after some days, the reason is a shock. You do not have to worry.
Take good care and give them some time to get used to the new environment. The plant will start growing healthy again.
Pests and diseases
Yellow leaves in houseplants might also be caused by pest infection and diseases.
Common pests that can attack houseplants are mealybugs, aphids, spider mites, ants, and scales. And the diseases caused by fungal and viral infections are Anthurium blight, bacterial leaf spot, mosaic virus, and gray mold.
The pest attacks and diseases occur if the plant is too wet. The conditions become ideal for them. Sometimes, pathogens transfer from outside factors like wind and rain.
To treat pest infection, first isolate the plant and remove affected parts to avoid spreading. Then, give the plant a good shower to wash away the pests. If pests remain, handpick them.
Next, apply neem oil. It works excellent on pests and diseases. You can also use mild dish wash soap to treat them. After that, you can wash off the plant.
If the condition is severe, apply pesticides or miticides to treat your plant. Read instructions carefully before using.
You need to remove the plant’s affected parts from the leaves to avoid further spreading of fungus diseases. Remember that the disease will again come back if the conditions are ideal for the plants. You can suppress the disease by using horticulture oils and fungicides.
You can generally apply neem oil once a month. If any pests or fungi exist in your plants, neem oil will treat them and prevent them from occurring again.
Natural yellowing due to aging
This cause is entirely natural and normal. The leaves become yellow as they complete their lifecycle. You must not worry about yellow leaves if it is due to aging.
The yellowing starts from the edges. Ultimately the entire leaf starts becoming yellow, and the leaves drop. You can remove the leaves if you do not like the sight of them on your houseplants.
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As you learned, there are several reasons for yellow leaves on your indoor plants. Different yellowing patterns will make it easier for you to detect the real reasons behind the yellow leaves.
Start treating the issues as soon as you see them on the plants. Be patient while treating them, as the plants will take some time to heal. Once the problem is addressed and treated, the plants will become healthy again.