In most cases, you try to bring home plants that look as healthy and vigorous as possible. So the best indicator that an indoor plant is unhealthy is to note how it is changing over time.
When tending to or watering your plants, take a moment to observe them closely, and keep an eye out for these common signs that your indoor plant is unhealthy.
Signs That Your Indoor Plant is Unhealthy
Leaves Falling Off
Leaves falling off the plant (called “leaf drop”) is an extremely common sign that a plant is unhealthy.
Most house plants lose a leaf or two occasionally, typically the older leaves near the stem, a plant that loses a lot of leaves, or loses new leaves, is an unhealthy plant. Leaf drop is usually caused by:
A Sudden Change in Environment
Outdoor plants that are brought indoors for the winter, tropical plants that are exposed to cold winter temperatures, or sudden changes in light conditions may cause leaf drop.
If new leaves are healthy and not falling off, this type of leaf drop is usually not fatal to the plant.
The Pot is Too Small
If a plant’s pot is too small, there isn’t enough room for the roots to develop and support new leaves.
This typically causes older leaves to fall off and the plant to become stemmy, but is not usually fatal.
The Plant is Being Watered With Very Cold Water
Some plants are sensitive to cold water, which chills the roots and may eventually kill the plant.
To prevent this, fill your watering can with tap water and then let it sit out overnight before using it to water your indoor plants. That allows the water to reach room temperature, and allows any chlorine in the water to evaporate.
The Plant is Overwatered
Some people respond to leaf drop by thinking that the plant is unhealthy and needs more water, when usually the opposite is true — leaf drop is much more often caused by overwatering than by under-watering.
To correct this, make sure that the plant soil is completely dry between watering.
Leaves Turning Brown and Crispy
As with leaf drop, it is normal for most plants to have some older leaves turn brown and fall off from time to time. If new leaves are affected, or if more leaves are browning than growing, it’s a sign that the plant is unhealthy.
Unfortunately, there is a difference between conditions where the entire leaf is turning brown and dry, and conditions where just the tips or part of the leaves are turning brown. Here are the most common causes of leaf browning:
If Whole Leaves are Turning Brown and Dry
The plant is probably under-watered
In some plants, it can also be a sign that they need more humidity in their environment.
Try watering more often or more deeply, and consider adding a humidifier or pebble tray, or placing the plant in a more humid room.
If the edges and sides of leaves are turning brown and dry
This is typically a sign of too much fertilizer, but may also be a sign of pests or disease. Most indoor plants don’t require frequent fertilizer or plant food, particularly in winter months when they aren’t in a period of growth.
If it isn’t excess fertilizer or plant food, read about leaves developing spots and speckles below.
If the Tips of the Leaves are Turning Brown and Dry
This is an incredibly common problem in indoor plants, and may be caused by any number of things.
It may be caused by erratic watering, tap water that is cold or chlorinated or has too many minerals in it, too little humidity in the environment, over-feeding, containers that are too small, pests and parasites, or a combination of factors.
If the plant seems otherwise healthy, check the pot to make sure the plant has enough room for their roots, and make sure that you water it on a regular schedule with tap water that is allowed to sit out at room temperature.
You may consider filtering your tap water to make it more plant-friendly, or adding a humidifier to the environment. Use sharp, clean scissors to trim off brown tips
Leaves Turning Yellow
Leaves turning yellow and wilting is a common precursor to leaf drop, and the two often go together.
If your plant has leaves that are turning yellow and falling off, refer to “leaves falling off” above. Here are some other common reasons for a plant’s leaves to turn yellow:
The Plant has Insufficient Light
Leaves will often turn yellow when a plant isn’t getting enough light. This is particularly noticeable in an indoor plant where leaves that face a window remain green, while leaves away from the window turn yellow.
Move the plant to a sunnier location, or rotate the plant regularly so that all the leaves are equally exposed to light.
The Plant Has Insufficient Nutrients
If new leaves are yellowing, or if a plant’s leaf tissues are turning yellow while the veins remain green, it’s a sign of poor nutrition. It may be caused by hard water, if you water has too many minerals, or by a lack of nitrogen in the soil.
If you don’t feed your plants, consider adding an all-purpose plant food. If you don’t filter hard water, consider filtering your water. This can be tricky to solve, so look up the specific nutrient needs for the particular plant species.
Leaves Developing Spots or Speckles
Leaves developing spots or speckles is very often a sign of a disease or pest. While it may sometimes be related to a plant’s nutrient levels, it’s best to first quarantine the plant while attempting to diagnose and correct the problem.
Because there are so many bacteria, fungi, and pests that can cause spots and random discoloration, it’s often a good idea to snip a leaf, place it in a tightly sealed plastic bag, and take it to your local garden center for diagnosis and treatment.
Variegated Leaves Turning Solid in Color
If you’ve chosen an indoor plant with lovely variegated foliage, it can be disappointing when it starts losing color and turning solid green. This is almost always caused by insufficient light, and can be corrected by moving the plant to a place with more light.
Leaves Are Wrinkled or Distorted in Shape
If a plant’s leaves are growing wrinkled, shrunken, or distorted in shape, particularly if new leaves are affected, this is most often a sign of a pest or parasite, although it may be caused by disease.
Quarantine the plant immediately, and inspect it carefully (particularly the undersides of the leaves) for signs of insects, fungus, or other problems.
Plant is Drooping
Generally speaking, if an entire plant is drooping, it is a sign of lack of water. Try watering the plant thoroughly, and it should perk up within a few hours.
If the plant is drooping and the soil is saturated, it may be a sign of over-watering. If the plant is in a pot that allows drainage, move it to a sink or somewhere that it can drain freely and fully.
Check the drainage holes and, if necessary, poke upward into the bottom of the soil with something like a toothpick to remove blockage, promote drainage, and allow air circulation into the soil.
Refrain from watering for a week or so, or until the soil is dry to the touch. It’s also a good idea to follow up with a fungicide.
White Crust or Mold on Surface of the Soil
A white crusty substance on the surface of your soil or the rim of your plant pots is typically a sign of excess minerals or salts.
Over time, these can damage the health of the plant, and are a common cause of rot in the root or leaves. To prevent this, “leach” your indoor plants once or twice a year.
To Leach a Houseplant
Move the plant to a sink or shower
Thoroughly flush the soil with water until it runs out of the drainage hole on the bottom.
As a rule, use twice the volume of water as the pot will hold; a 6-inch plant pot holds 10 cups of water, so flush the soil with 20 cups of water.
Wait 30 minutes to an hour, and flush the soil again
Allow the plant to sit and drain in the sink or shower for an hour or two before removing it.
This is also a great time to rinse or wash the leaves of your houseplants, spraying them gently with water to remove built-up dust or debris.
It is also a great time to wash the outside and inner rim of your plant pots, which will also remove excess salts.
Keeping an eye out for these common signs of unhealthy houseplants will help you catch and treat problems early, allowing you to preserve the health of your indoor plants and prevent problems from spreading.