Dieffenbachias are prized for their large leaves that create a lush, tropical atmosphere in whatever room they inhabit. However, one of the most frequently reported problems that people have when growing dumb cane as a house plant is that the leaves become small and stunted. Why does this happen?
When Dieffenbachia’s new leaves become small and stunted-looking, it is usually a sign of a pest infestation – either spider mites or mealybugs. It can also be due to an inappropriate watering schedule, over-fertilization, not getting enough light, or being root bound.
Luckily there are ways to fix a stunted dieffenbachia with small leaves, but first, you have to figure out the underlying issue. In this article, we discuss how to troubleshoot growth issues with Dieffenbachia and what you can do to address the problem.
Why Are My Dieffenbachia Leaves Getting Smaller?
If you have had a dieffenbachia house plant for a while and suddenly notice that the new leaves are becoming smaller and smaller, it is a sure sign that there is something wrong with the plant.
Dieffenbachias’ leaves can become stunted and small for a number of different reasons that are all related to plant care. To keep dumb cane leaves growing nice and large, you have to ensure the plant has optimal growing conditions.
Let’s look at the five most likely reasons that dieffenbachia leaves get smaller:
1 – Pest Infestations
Sap sucking insects like spider mites, mealybugs, aphids, and scale insects are all common pests that affect dieffenbachias. They cluster around the plants’ new shoots, stealing its sweet sap. Large numbers of these sap sucking pests can severely weaken the plant and stunt new leaf growth.
If you see lots of tiny insect-looking things on your Dieffenbachia’s new leaves and shoots, have a closer look to identify them:
- Spider mites can be red, green, or brown in color. Their tiny bodies are oval-shaped and they produce white, cobweb-like strands all over the plant.
- Mealybugs are white or light grey, fuzzy, oval-shaped insects.
- Aphids are tiny, pear-shaped bugs that can be green, black, white, brown, yellow, or pink in color. They have long antennae.
- Scale insects form small, hard, circular bumps on plants’ leaves and stems. They range from brown to white in color.
2 – Overwatering
Overwatering is one of the most widespread issues with houseplants. If you water too often or the soil does not drain fast enough, plants will start showing signs of stress.
If you do not allow dieffenbachias’ soil to dry out in between watering sessions, you run the risk of overwatering. Overwatered dieffenbachias develop root problems which cause the new leaves to grow smaller.
3 – Overfertilizing
Dumb cane is a fast-growing plant that benefits from a little nutrient boost every now and then. Fertilizing a dieffenbachia can spur its growth along, but too much fertilizing hinders its growth.
Overfertilizing leads to a build-up of mineral salts in the soil. These draw moisture away from the plant roots, burning them. This is known as fertilizer burn.
Usually, the first sign of fertilizer burn is brown leaf margins and crispy leaf tips. You may also notice a white crust on the soil surface. This indicates salt build-up.
When a dumb cane is stressed from overfertilization, the new growth can become stunted, and the leaves grow smaller than usual.
4 – Low Light Levels
Another reason why a dumb cane’s new leaves are small is insufficient light. Although they are plants that can thrive in lower light conditions, too little light can hamper the plant’s growth.
The optimal position for a Dieffenbachia is in bright, indirect light. Often in winter, when the angle of the sun changes and the number of daylight hours decrease, you may have to move your dumb cane to a brighter spot. Otherwise, the leaves may become small and stunted.
5 – Being Root Bound
Dieffenbachias don’t mind their roots being a little snug inside the pot, but when they become properly root bound, they start to show signs of stress. Root bound dumb canes struggle to get the water and nutrients they require, so their growth slows down or becomes stunted.
If you see the plant’s roots poking out the bottom of the pot, the reason the leaves are growing smaller is that the plant is root bound.
How to Help Dieffenbachia with Small Leaves
Once you figure out what is bothering your Dieffenbachia, you should immediately address the problem. Here’s what you can do to help a stunted dumb cane:
- Treat pest infestations. All sap sucking insects can be treated with horticultural oil or neem oil.
- Make sure that you do not overwater the plant. Always check that the soil has dried out before watering.
- Place the plant in the bathtub or shower and water it thoroughly. Let the water run out of the pot’s drainage holes so that mineral salts are flushed from the soil.
- Make sure the plant is in a spot that is bright enough. Dumb canes should not be in harsh, direct light.
- Transplant the plant into a slightly larger pot. Giving the roots fresh soil and more space to grow will make the leaves grow larger.
Dieffenbachias’ leaves can become small and stunted for a few reasons – pests, too much water, too much fertilizer, too little light, or because they are root bound. Once you have figured out which of these is the underlying issue, you will easily be able to fix your struggling dumb cane.
To ensure that your Dieffenbachia keeps growing large, lush leaves, you have to keep it in the correct growing conditions. These tropical plants love bright, indirect sunlight, plenty of humidity, and not too much water.
You should repot a dumb cane every few years to keep it from getting root bound.
Growing up with a mom who filled her home (inside and out) with all sorts of plants, Lisa got her start in gardening at a young age. Living now on her own with a home and yard full of plants (including an indoor greenhouse), she shares all the gardening tips she’s gained over the years.