It’s easy to spot problems in your houseplants when they are visible in the leaves or flowers. What about potential issues that are going on under the soil, with the roots?
Don’t forget to take care of your plants even when you can’t see what’s going on. In particular, we’re talking about when a plant outgrows its container, and how to fix a root bound plant.
What Is “Root Bound”?
Even though you never see it, there is a lot of growth going on inside that pot. And eventually, the roots are going to run out of space to grow properly.
As they come up against the inside surfaces of the container, they start to grow in a circular direction in the only way they can.
This is where the problem comes in. Once the roots start that pattern of growing around in a circle, even transplanting to a bigger pot won’t be of much help. The roots will continue that same behavior, no matter how much extra space they have.
In other words, they stay all cramped up in an unhealthy ball no matter how big of a container they move into.
Why It’s a Problem
You have to remember that the soil in the pot isn’t just an anchor to keep your plant standing upright. There is a lot going on under the surface of your potting soil, and bound up roots will be detrimental to the plant.
For one thing, a container that is filled up with roots isn’t going to have enough dirt in it to hold a sufficient amount of water for the plant. You will continue to water as usual, yet the water will flow much faster through the pot, leaving the plant high and dry almost immediately.
Another aspect of this is that there are also a lot fewer nutrients in a pot full of roots. This leads to a malnourished plant that will not thrive. There needs to be more soil.
How to Tell If a Plant Is Root Bound
It’s not an easy problem to notice because there aren’t a lot of obvious signs that a plant is outgrowing a container or getting root bound.
One clear symptom is that you start to see roots growing out of the drainage holes in the bottom of your container. Besides that, most plants will give the same symptoms of under-watering, with yellowing or wilting leaves.
Does your plant look disproportionately large for the container? That can be another sign that it’s getting crowded inside the pot. Lighter weight plastic pots can even start to be misshapen as the force of the growing roots pushes out from the inside.
If you suspect that your plant needs a bigger home, the only real test is to get a little dirty and remove it from the pot to see the roots directly. Are they taking up more space in the pot than the soil, or clearly circling around in search of more room?
Time to get a bigger container and move your plant.
How to Transplant
The only solution for fixing a root bound plant is to move it to a larger container to give the roots proper space to grow and unfurl. If you’ve caught your plant before the roots are seriously bound up, you can just repot and let the plant stretch out into the new space on its own.
But as we mentioned earlier, a root bound plant will need a little more care to fix the problem.
You’ll need a larger pot, and one that is big enough to last a while so you’re not having to do this chore too often. If your plant space is getting crowded and you just can’t find a spot for a huge container, you may need to consider splitting the plant into two instead.
You will also need a bag of potting soil. Having some newspaper or a drop cloth can also be helpful so you don’t make a mess all over the room.
In the new pot, add a layer of fresh soil that is deep enough so that when the root ball is set inside, the top of it is about an inch below the rim of the pot (you need to allow room for water). Spread your fingers over the surface of the soil in the existing pot, and brace it while you flip the pot upside down.
Ideally, the it should slide out into your hand while doing no damage to the plant. If the roots are seriously protruding from the drainage holes, you will have to trim them first to set the plant free.
Now set the root ball in the center of the new pot, and double-check that you are leaving that gap of space at the top. For a heavily bound-up plant, you will need to loosen up the matted roots to encourage the plant to grow outward again to use the new soil in the pot.
Gently pull them apart, and even do a little snipping to encourage fresh new roots to start growing.
With the plant sitting in the middle of the new container, pour fresh soil in to fill the space, gently patting it down as you go. Give the plant a thorough watering, and add more soil if necessary (the water can make fresh soil settle downward).
That’s all there is to it.
Preventing Root Binding
There is nothing you can do to slow down your plant’s growth to keep it comfortable in the same small container indefinitely. The key is to get the plant moved to a larger pot before it fully outgrows the original container.
Take regular peeks at the drainage holes to look for protruding roots, or just assume that a larger pot is necessary every year or so rather than waiting for problems to show themselves.
While we are talking about containers and root health, it can be helpful to know more about fertilizer options to ensure that your houseplants are getting all the nutrients they need. Which type of fertilizer will depend on the type of plant you are dealing with.
Is it mainly a green plant, that you grow for the foliage rather than the flowers? Then you want to keep a higher nitrogen formula around for them. If you prefer a natural option, find a product made with seaweed emulsions or blood meal for this.
Flowering or fruiting plants? Add something with more phosphorus instead, and keep the nitrogen a little lower. Bone meal and fish emulsions are good.
In either case, a commercial formula will be labeled with 3 numbers, known as its N-P-K rating. The first number is nitrogen (higher for the green plants) and the second one is phosphorus (choose higher for flowers).
Indoor or Out?
We’ve mainly been talking about root bound plants from an indoor or houseplant perspective because that is the most common situation that leads to pot bound plants.
The truth is, it can happen to your outside plants as well, given the right circumstances. Obviously, the first possibility is any outdoor container plants, in which case, you handle them like any root bound houseplant.
But roots can get bound up against underground obstacles you aren’t aware of. Large rocks, a foundation, pipes or pretty much anything else can be under your garden bed that you don’t know about, restricting the root growth of your outdoor plants.
When this happens, you will have to either dig up the plants and remove the obstacle, if it is something movable (like a big stone). Otherwise, you will need to find a new location altogether that has more space for the roots of your plants to grow.
As you can see, dealing with good root health in houseplants can be more in-depth than you may have though. So take good care of your indoor garden and make sure to move your plants before they burst from their pots.
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.