Why do leaves turn yellow on plants? Lots of people ask this at some point. So many things can cause yellowing leaves, from the type of fertilizer you use to how much you water. Luckily, you can diagnose the reason leaves turn yellow on your own, with just a little know-how. Let’s get to the root of this problem and explore what can cause yellow leaves!

Nutrient Deficiency

Yellowing leaves on a houseplant

Why are your plants’ leaves turning yellow? It could be a nutrient deficiency! The most noteworthy culprits as far as deficiency goes are nitrogen, potassium, magnesium, and iron. Many types of deficiency manifest in the form of chlorosis, which is leaf yellowing around the leaf veins specifically. This tends to give them a fairly distinct, and therefore diagnosable, look.

How to Fix:

To address nutrient deficiency, you’ll either need to apply some good, old-fashioned fertilizer or better-balanced fertilizer to the soil. Sometimes, too much of one nutrient may inhibit absorption. Everything needs to be kept in balance and in check!

Pests

Yellow leaves because of pests

Usually, you will be able to easily tell if pests are the reason your plant’s leaves turn yellow! The yellow spots on plant leaves will often surround bite marks or ‘bullet’ marks (indented, ringed spots, similar to bullet holes).

There may be entire patches of yellowing leaves, and if you look closer, you may get a look at the pest itself. The most common pests are aphids, whiteflies, scaly bugs, spider mites, and thrips. The majority appear as tiny winged bugs, while the others may resemble scales or fluff.

How to Fix:

Most pests can be addressed with a simple pesticide. There are commercial chemical pesticides and more natural options like neem oil. Simple dish detergent and water may also do the trick. Pests are quite common and are normally easy to root out, never fear!

Underwatering

Yellow leaves because of underwatering

Why are the plant leaves turning yellow? Perhaps the biggest cause of leaf yellowing (with a few close runners-up) is an imbalance in how much you water. Moisture deficiency will cause your plants to dry out, from the roots up. Ultimately, the leaves will yellow or brown and ultimately fall off.

How to Fix:

While it will vary by plant, most require hydration every few days or so. You may find that tropical varieties require more water. Succulents and cacti, on the other hand, typically require less. As a basic guideline: once the top layer of soil has dried to about a 1-inch depth, you probably don’t want to wait much longer to give them the hydration they need!

Overwatering

Yellow leaves because of overwatering

Whole plant turning yellow? A common mistake is to kill a plant with kindness (which can cause yellowing leaves), that is, giving it too much water. It’s clear that plants love being hydrated, and this mistake is not at all unusual. Sadly, deadly molds love soil moisture, too; only, they require conditions that are even wetter. So, when you overwater, it may not harm them directly or yellow leaves on plants, but it will give any harmful molds or bacteria living in the soil a chance to grow which can lead to diseases.

How to Fix:

Make sure to water just enough, not too much or too little. Remember to check the soil first. This should do the trick and prevent disease!

Insufficient Light

Yellow leaves because of insufficient light

When a plant doesn’t receive sufficient light, it won’t produce enough chlorophyll. This will cause yellowing leaves on plants and poor health.

How to Fix:

Make sure that all of your plants have ample light (but not too much or too direct; it varies). Don’t leave any leafy friends in rooms that are dim or dark. Outdoor plants that love sun should not be situated in the shade, either!

Excessive Light

Yellow leaves because of excessive light

It’s true that plants love and depend on light, but there is such a thing as too much of a good thing. Excessive or overbright sunlight will not benefit your plants but rather cause them to overheat and sunscald (AKA a sunburn, from which afflicted yellow leaves on plants don’t typically recover).

How to Fix:

Don’t place plants except for cacti and other sun-lovers in direct sunlight. Make sure that they have the necessary distance from windows and bright light. This should give their overheated, yellowing leaves a break!

Improper Soil pH

Yellow leaves because of improper soil pH

Every plant has a preferred soil pH, from anywhere between 1-14 (usually somewhere in the middle). If the soil is too alkaline (14) or acidic (1), it can cause discomfort. The plant’s roots may even have trouble absorbing the necessary nutrients from the soil. This can contribute significantly to a plant’s leaves turning yellow!

How to Fix:

A simple pH tester purchased online or at the store can show you the pH of your soil. If it’s in the right range, pH is unlikely to make the leaves turn yellow. If it’s too acidic or too alkaline, balancing it out properly might just do the trick!

Overhead Irrigation

Yellow leaves because of overhead irrigation

While overhead watering is perfectly alright for some plants, there are others that simply don’t appreciate it. It can cause their leaves to acquire burns, as with the African Violet  – or patches of white, light brown, or yellow!

How to Fix:

To help prevent damage from overhead watering, all that you need to do is directly irrigate the soil, leaving the leaves completely dry. Switch to a spout watering can rather than a perforated one to spare the leaves’ contact with the liquid.

Transplant Shock

Yellow leaves because of a transplant shock

Last but not least, we have transplant shock. Stress can absolutely be the reason why the leaves turn yellow, and one of the biggest stressors they can experience is transplant shock. If you’ve recently repotted a plant, expect a few leaves to turn yellow.

How to Fix:

Yellowing plant leaves from transplant shock should stop within a week or two. If it continues for a long time, excessive damage may have been done to the roots - or something else, like a disease, may be the cause!

So, do you have a better idea of what might be causing your plant leaves to turn yellow? Once you’ve gotten to the root of the cause, you can promptly apply a fix. In no time, you’ll have your leafy friends feeling much healthier and greener.