You would think that an underwatered Monstera plant just needs a drink. Makes sense. If it’s thirsty, give it water. The trouble is that different conditions cause the plant to go through more water or less.
Monsteras are good at regulating their watering. They consume what they need. All you need to do as a responsible plant parent is keep some moisture available in the potting mix for the roots to absorb.
When the soil drains faster though, you can find yourself going to battle with a Monstera that is drinking like a fish, yet still showing signs of dehydration. At that point, the cause needs some investigating.
Without knowing why your Monstera is constantly looking thirsty, the inevitable outcome of continuously watering will be overwatering your plant, leading to catastrophic consequences of it wilting and dying from root rot.
Know what causes Monstera plants to become underwatered and you can nurse them back to health fast.
Signs of an Underwatered Monstera
1 – Leaf Curling
When you see your Monstera leaves curling in on themselves, it is a certainty that the plant is underwatered.
Leaf curling is a behavioral trait of the Monstera (and many other tropical plants) to conserve moisture. The less surface area there is for water to evaporate through the stomata on each leaf surface, the longer the plant can maintain the moisture.
Within every leaf on Monstera plants, a huge amount of moisture is there. Or should be. When it starts to struggle, the leaf folds in on itself. This is sometimes called cupping.
Given the size of leaves on Monstera, they will not cup right over like some plants do, but instead, only the leaf edges will curl upward.
Misting the leaves is not going to be enough to unfurl the edges. They need hydrated inside and that can only be done by getting water to the roots and letting them nourish the stems and foliage.
That is the role of the roots. Your role is to nourish the roots so they can care for the plant.
2 – Leaves Drooping
The Monstera has a monstrous number of stomata on each leaf. These open and close to regulate temperature, however, climate control is paramount to prevent the plant losing too much water vapor too fast.
When water evaporates faster through the leaf pores before it can be replenished from the soil moisture, the Monstera plants will show the symptoms of underwatering. The leaves droop when the water vapor is lost through transpiration before being replenished from the moisture in the soil.
The problem may not be that the soil needs to be topped up with water. But instead, the moisture in the air needs to be increased to slow down transpiration.
Arid conditions can cause Monstera leaves to turn yellow, and droop.
If you suspect underwatering is an issue, always test the soil to make sure it is dry to at least one-inch before adding water. When the humidity is too low, the leaves show signs of being underwatered, but the soil will still be moist.
Adding water to already moist soil will worsen the plants condition as overwatering is far worse for any plants than not providing enough water.
3 – Compacted Soil
Coincidentally, compacted soil usually happens when the plant has been overwatered. Give it time to dry out and then start watering. Things may improve. Oftentimes though, that’s not what happens.
The problem with overwatering is that is not just the standing water that can drown the roots. It’s the structural damage that it does to the soil.
Potting mixes have ingredients in them such as perlite to improve aeration. When too much water collapses the soil structure, air pockets are reduced.
The roots of plants need to have access to water and oxygen. The air pockets do that. Damage to the soil’s structure from too much watering can lead to an underwatered Monstera because compacted soil lacks aeration.
Depending on the extent of the damage, you may need to either aerate the soil to improve the structure, or repot your Monstera in a fresh potting mix.
4 – Crispy Discolored Leaves
The leaves on a Monstera should feel waxy and smooth. They should never be crispy. If they are, they are dry. Dry leaves are definitely a sign of underwatering. You will notice the leaves drooping too.
Yellowing leaves is natural on new leaves, but when the yellowing or sudden browning appears sporadically on mature leaves, it can indicate other problems such as mites, mealybugs, or even a fungal infection.
Discoloration on Monstera leaves is tricky for diagnosing anything. Because, yellow leaves can be caused by overwatering and underwatering. Either causes partial yellowing.
Fully yellow leaves are caused by underwatering. Yellow leaves with brown spots are caused by overwatering. That being said, dry light brown spots can appear on leaves that are too dry.
The only real way to tell what is causing leaves to lose their greenery is to test the soil moisture. Not just the top soil, but to a depth of at least a couple of inches.
5 – Root Bound
Monstera plants like to spread their roots. In a potted container indoors, the spread is limited to the size of the container. It will spread its roots until it no longer can.
When that happens, the roots crowd the pot. A root bound Monstera will not be able to absorb much water from the container.
What happens when you have a high root-to-soil ratio is that multiple signs of underwatering appear. Yellowing leaves, stunted growth, and smaller leaves.
Quite possibly, the fenestration on mature leaves will fail to occur. Underwatered Monstera leaves only split when the growing conditions are favorable.
To bring it back from the brink and get sufficient hydration, repotting a root bound plant is an absolute must.
How to Fix an Underwatered Monstera
There are two fixes for a Monstera plant showing signs of underwatering. The first and simplest is to water it thoroughly.
However, if the soil drains too fast that it dries out before the plant can use it, the other fix is to repot it in a fresh potting mix suitable for the plant.
Method 1: Bottom-Watering an Underwatered Monstera
The bottom watering method is a preferred way to fix any plant that has been underwatered. It lets the potting mix act like a sponge, soaking up as much moisture is needed.
Simply fill a sink, basin, or put some water in the bath and sit the plant in its container. The drainage holes will do the work of absorbing the water into the potting mix.
Not much water depth is needed. Enough to cover a couple of inches of the pot.
The top of the pot should not be submerged in water, as that would defeat the purpose and drown the plant.
Leave the top exposed and check the moisture at ten-minute intervals. The top of the soil should be damp. Once it is, remove the pot from the water and leave it for an hour to two hours to drain.
Excess water will drain through the drainage holes. Leave it until no water is dripping and then replace it in its decorative container, or on a tray.
The reason to let it drain before setting it back in its usual spot is so that it is not left sitting in standing water, risking root damage from soggy soil.
The one thing to keep in mind with bottom watering is that it should not be used consistently. Top watering has its advantages, the main one being that it flushes the soil.
Without top watering, excessive salts from fertilizer in the mix will accumulate. If you were to rely on bottom watering every time the plant needed watered, the soil would never get flushed.
You would go through far more potting mix from repotting more than necessary because it would compact frequently.
Method 2: Repot an Underwatered Monstera
When the potting mix is consistently dry, despite your constant watering, it will be that the soil has lost its ability to maintain moisture. It happens eventually with all potting mixes once the ingredients wear away.
As a general guideline, growing a Monstera indoors will require repotting it in a bigger container every two years. If you would rather maintain its size, root pruning is the only other alternative.
Something to remember about plant growth is that there are roughly equal amounts of growth above the soil as there is below. The bigger your Monstera, the bigger the roots will be.
When repotting, if you do want to stay with the same size of container, trim about a third of the root ball, and then repot with a fresh potting mix.
If you are content to let your Monstera continue growing larger, give it a bigger pot to spread its roots. And keep doing that until you need to tame its growth.
You will find that after the roots have room to spread, the plant will drink in moderation, and you’ll have lush green flat fenestrated leaves without any of the signs of underwatering, provided you keep watering only when the potting soil is dry-to-the-touch.
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.