Yellow leaves on your houseplants? Here's what they're trying to tell you

Yellow leaves on your houseplants happen at some point, even with expert plant parents. If you are seeing yellow leaves, it means that your plant is telling you to pay attention and that something needs adjusting. Fix the cause and your plant will perk up again.

The causes are pretty basic: too much or too little water, incorrect light levels, lack of nutrients, drafts or maybe just natural leaf loss. A yellowing leaf is one of the most common signals a plant sends, and once you know how to read it, it’s not that alarming.

Overwatering and underwatering: the most common causes of yellow leaves

Overwatering

This is the most frequent culprit. If your plant leaves have turned yellow and mushy and the pot feels heavy, then your plant is telling you that it has too much water. When the potting mix is too wet, the roots drown due to a lack of oxygen. The roots suffocate and can’t deliver water and nutrients to the plant.

What to do about overwatering 

Let the potting mix dry out fully before watering again. When you water next, stick your finger into the potting mix to see if it is really dry before watering. Always make sure that your pot has drainage holes and that you empty the overflow saucer of drained water.

Most plants coming from garden centres are grown in good potting mixes that are lightweight and offer a proven balance between aeration and water retention. When repotting or planting new cuttings, the growing medium you choose should match your plant's specific needs. Use a proper potting mix like Schultz Potting Soil Plus.

Repotting or planting in standard soil, compost or black earth should be avoided. It will not provide proper aeration and will retain water.
 

Underwatering

You know that you forgot to keep up with watering when your plant’s leaves turn yellow and curl inward, your potting mix is bone dry, and the pot feels very light. If your plant doesn’t receive enough water, older leaves will shrivel up and drop off. Before they drop, the leaves typically turn yellow.
 

What to do about underwatering 

Water thoroughly and find a more consistent rhythm. Small pots dry out faster than bigger pots. Maybe it’s time to go up a pot size. If you let the potting mix get really dry, water may not be absorbed but will instead flow down the sides of the pot and out into the saucer. No moisture gets absorbed into the overly dry potting mix.

In that case, immerse the whole potted plant into a sink or pail full of water until the air bubbles stop. After a good soaking, put the plant aside to let excess moisture run out. Press the potting mix against the edges of the pot to make sure it’s tight again.
 

Wrong light levels and yellow houseplant leaves

Lack of light

All houseplants need sufficient light to create chlorophyll, which absorbs sunlight and helps create the plant’s own food. Without enough light, the plant sheds the leaves it can no longer support. Plants that receive too little light will often start to yellow on the lower or inner leaves.
 

What to do about a lack of light

Move the plant to a brighter location. If a plant has one of its sides facing a window, one side gets all the light, and the other side gets little. Rotate the pot at every watering so all sides get their fair share of natural light.
 

Too much bright light

The leaves will look bleached, scorched or develop yellow-brown patches. Most tropical houseplants come from the forest floor and aren’t suited for full sunlight. The sweet spot for most houseplants is bright indirect light. There are plants that do well with a few hours of bright sunlight a day, such as any succulent or cactus, aloe vera, hibiscus, lantana, croton and ponytail palm.
 

What to do about too much bright light   

For most tropical houseplants that are showing signs of overexposure, move them to a spot with less direct sunlight, or use sheer curtains to filter out the direct sunlight. Whenever you’re picking out a houseplant to move into your home, you need to take note of what it needs for light. Light needs will be printed on the plant tag, or you can verify that plant’s particular light requirements online or in books.
 

Nutrient deficiency: when your plant is running on an empty tank

Lack of nutrients

Houseplants will develop yellow or paler leaves if they’re missing out on some key nutrients in the potting mix. When they first come home from a garden centre, most plants are well fertilized. However, after a while, they will use up the food they came with and will need a regular boost to maintain their health.  
 

When to fertilize houseplants and what to use

Use Schultz All Purpose Liquid Plant Food as an uncomplicated way to remember feeding your plants. At 7 drops per litre of water, you are giving a diluted feeding every time you water.

A lot of plant parents cannot remember when they last fed their plants, so instead of applying a full dose of fertilizer once a month (if you remember), feed your plants with Schultz every time you water for a consistently proper dose.
 

Other reasons your plant leaves are turning yellow

Drafts

Any tropical plant that is exposed to cold drafts near an air conditioning vent or a drafty door or window in winter may show its disapproval with leaves that turn yellow and drop. The same goes for hot air from heating vents or fireplaces.

Solution: Move your plant to a less turbulent spot.
 

Natural leaf loss

Not all yellow leaves are a problem. Older lower leaves yellow and drop as part of normal growth. If only one or two leaves are affected and the rest of the plant looks healthy, there is nothing to worry about.
 

Pests 

Sooner or later, every plant parent may be visited by plant insects. Common sap-sucking insects like aphids, spider mites, mealybugs and scale feed on the plant’s juices, severely stressing the plant. They will turn the foliage yellow and splotchy.

Solution: Check the underside of leaves for infestation. Applying Schultz Insecticidal Soap will control and keep bug problems in check.

Yellow leaves are usually caused by overwatering, poor light, low nutrients, drafts or natural leaf loss. Identify the cause, make one adjustment at a time, and your plant will tell you if it's working.

Don’t expect yellow leaves to suddenly green up again. That doesn’t happen. But remember that yellow leaves are a conversation, not a crisis. A plant that shows you what it needs is a plant you can help. That's the spirit of proper plant care.