When the potting soil of an indoor plant becomes hard, clumpy, and immovable, the rate of airflow, waterflow, and nutrient flow to the plant can be cut off. If you have compacted soil in a potted plant, rather than just repotting the plant and throwing the potting soil away, you can revitalize the hardened potting soil by loosening it, but how? What are some easy ways to loosen compacted and poorly aerated soil in your potted plants?
Here are a few easy ways to loosen compacted soil in potted plants:
- Poke a chopstick (or similar instrument) into the soil, breaking it up
- Add aerating materials like peat moss and perlite
- Make vermicompost with live earthworms
In this thorough guide, I’ll first explain how soil compaction happens and why it’s dangerous to your plants. Then I’ll delve into step-by-step instructions on how to do each of the above soil aeration methods. Aerating your soil will help you get more out of it, so you definitely won’t want to miss this!
Why Is My Houseplant Soil Hard?
Let’s begin by talking about the reasons the soil in your potted plants has become hard and compacted in the first place.
The Potting Soil Is Old
How old is your plant’s soil? Even if the potting soil isn’t growing mold nor is it attracting pests, that doesn’t mean it’s going to last forever. When it comes to how often you should put in fresh potting soil or potting mix, the rule of thumb is this: If your plant is a fast grower, then switch out the soil about annually. For slower-growing plants such as the snake plant, you can wait a little longer.
Old soil has absorbed many waterings. It’s full of fertilizer, nutrients, and who knows what else? It’s hard to remember. The contents of the old soil can create blockages or limit the air pockets in the soil, neither of which is good for your houseplant (keep reading for more on this).
You Used the Wrong Type of Soil
Using the wrong type of soil on indoor plants is something I’ve discussed in a few posts here on Indoor Plants for Beginners . But for this post, just know that: Topsoil or outdoor soil should not be used with any indoor plants, potted plants or when doing any kind of container gardening in general.
I know that seems obvious when you read it, but yet when you’re at the gardening supply store, it can be easy to buy the wrong type of soil by mistake. If you grab topsoil instead of potting soil, it looks about the same, so you might figure what’s the difference?
The answer is a lot. Topsoil is formulated for outdoor plants that are often larger than houseplants. These outdoor dwellers have different needs, so the soil is not going to be the same.
For one, the soil might weigh a lot more. The weight of the soil you choose for potted and container gardening matters because it can directly affect the ability of the soil to remain aerated and not become compacted. It’s also important to note that topsoil also has a different mix of nutrients then the bag of potting soil you should be using.
I also discourage you from using soil from your backyard, as convenient as that might sound. Backyard soil is rarely pure soil at all and will also include silt and clay. It too is heavy and won’t benefit your houseplants since it’s not going to have the nutrients your potted plants need to be healthy and thrive.
The Aerating Materials Died or Were Flushed Away
Potting mixes often include aerating materials such as coconut coir, perlite, vermiculite, or peat moss. These materials not only create air pockets throughout your plant’s soil, but they can retain water as well. For many plants, perlite, etc. creates the perfect conditions the houseplant needs to thrive.
Yet peat moss only lives for a year or two. When it’s dead, it’s probably not absorbing water, and it may not do much for your soil aeration either. Vermiculite pellets and coconut coir chunks can be washed right out of the pot’s drainage holes with repeated waterings.
Obviously, you can’t stop watering your plant, so the above scenario is all but inevitable. You probably can’t tell when your potting mix is more dirt than perlite, but your houseplant will certainly notice the difference. What follows is soil that’s a lot harder.
The Risks of Compacted Soil
Hard, compacted soil can cause a whole bevy of issues with your houseplant, some of which could even kill the plant. Here’s a list of problems to be aware of.
Lack of Water Flow
In aerated plant soil, water can travel freely from the top layer of the soil all the way to the roots. Compacted soil is like trying to take a walk but half the streets in your neighborhood are blocked off for construction. You can only go to so many places.
This complicates matters for new indoor gardeners considerably. Getting the hang of when to water your houseplant is not easy when you’re a green indoor gardener. I always say that instead of using a set schedule, you should put a clean finger into the soil to feel how moist it is. Dry soil necessitates watering while moist soil does not.
Now imagine this scenario. You finally feel like you’re watering your houseplant adequately, yet it doesn’t seem like it. Your plant’s leaves are no longer healthy green, but yellow. The edges of the leaves may have even turned brown. The texture of the leaves is crispy, and the plant is drooping.
In other words, it’s a classic case of underwatering, right? Except it isn’t. You’re watering your plant the right amount, but the compacted soil is stopping the water from reaching the plant’s roots.
Following the example from above, here’s what most new indoor gardeners would do when they see their plant is wilting. They’d water their plant more. After all, clearly the amount of water they’re giving their plant is not cutting it, right? That appears to be the case, yet it isn’t.
Although I’ve established that water can’t travel as freely as necessary in compacted plant soil, that doesn’t mean it can’t travel at all. If you water the soil enough, it will get soggy and saturated. Whatever air pockets were within the soil are now filled up with water.
If you’ve ever been underwater for too long in a swimming pool or the ocean and you felt like you couldn’t breathe, you know how terrifying that is. This is exactly what’s happening to your plant. Its oxygen supply is cut off, which is one of its basic requirements for life. The plant can drown in its pot.
Should the water somehow reach the roots, now you have another problem to contend with: the dreaded root rot. Standing water causes root rot, a condition that kills the plant from the roots up.
Now, you’re probably wondering, what about your plant’s drainage holes? Can’t the water exit there? The drainage holes are still working, but the water isn’t getting to the holes since it’s stuck within the compacted soil. You might as well not have the drainage holes at all.
Even if your houseplant isn’t drowning in trapped water, it’s still not getting as much oxygen as it requires if its soil is compacted. Although plants can photosynthesize and produce oxygen that way, they’re just like you and I in that they need to breathe. Except for plants, this form of breathing is known as respiration.
Well, that’s not all respiration is. When a houseplant respirates, it takes the sugars it made from photosynthesis and combines them with oxygen. The result is energy that the plant uses to sustain itself and to grow new parts, including stems, leaves, and flowers.
Respiration can’t occur with just sugar, so without enough oxygen, all growth will stop. If these conditions progress for long enough, the plant possibly may not even have enough energy to sustain its own growth.
When you go to replenish your indoor plant with fertilizer, what do you think will happen? As you probably guessed, the compacted soil will limit the progress of the nutrients. Some might get through, although it in what quantities, it’s impossible to say. Other nutrients can get trapped at the top of the soil far from the plant’s roots.
Plants rely on nutrients for survival. Nitrogen helps your plant synthesize enzymes, nucleic acids, chlorophyll, proteins, and amino acids. Potassium keeps carbohydrates, nutrients, and water traveling consistently through a plant’s tissue. The nutrient also kickstarts the process of enzyme activation to produce more adenosine triphosphate or ATP as well as starch and protein. ATP especially is crucial, as it affects how often a plant photosynthesizes.
Don’t think I forgot phosphorus, as I didn’t. Phosphorous helps plants retain their genetics and encourages the travel of nutrients. Photosynthesis happens in part due to phosphorus, as does any energy transference.
Like we people can develop nutrient deficiencies from a poor diet, so too can your houseplant. A nitrogen deficiency will cause yellowing or pink leaves and an overall spindly appearance. Without enough potassium, your plants will develop chlorosis or leaf margin yellowing. Then death can follow. With a phosphorous deficiency, your poor houseplant will turn pale with bluish-green foliage and dull-looking leaves.
Reduced Root Growth
A plant’s roots like to stretch out and settle in. With so many blockages throughout the compacted soil, the roots can’t go much of anywhere.
If the roots don’t stop growing because your plant is starved of oxygen and thus energy, then the roots could spiral around the pot until your houseplant is rootbound.
It’s true that there are some potted plants that actually thrive as a root bound potted plant. But it’s also true that in some cases, a rootbound plant can die as its roots become too tangled and the plant ends up choking itself.
That said, it’s important to know if the potted plant you’re caring for flourishes when it’s in a tighter root ball or if it’s the type of indoor plant that needs room for its roots to spread out to grow.
The Best Soil Aeration Methods (Step by Step)
You’re ready to aerate your houseplant’s soil today. Doing so can be easy, as I’m going to give you a few methods you can follow along with and try.
These include using chopsticks, adding perlite or other aerating materials, or even nourishing your plant’s soil with vermicompost (which yes, features real live earthworms).
Here’s what you need to know to easily aerate your indoor plants potting soil
How to Aerate Your Potted Plants Using Chopsticks
The chopstick method is arguably the easiest way to aerate your plant’s soil is with a set of chopsticks or a similar instrument. These are the steps to follow.
Step 1: With your chopstick, poke into the soil from the top down. Just be aware that the roots can be delicate as you’re poking down into the soil their attached too. You can also sift through the soil if you’re worried about hitting a root, which can happen.
Step 2: Water your houseplant, focusing on the openings you’ve created with the chopsticks. The water should move right out of the pot’s drainage holes.
Step 3: If the water doesn’t drain easily through the hole in the bottom of the container, then repeat Step 1 until it does. That’s the main goal we’re trying to achieve here. Getting the air and water to be able to easily move through the soil. That’s all there is to the chopstick method!
How to Aerate Your Plant by Adding More Aerating Materials
If your soil has long since been depleted of aerating materials, replenishing them doesn’t hurt. I’d recommend peat moss, vermiculite, and perlite for sure. If your plant is a succulent or otherwise doesn’t mind drier conditions, then sand is a good soil aerator too.
Step 1: Make your soil mix. Combine one part potting soil with one part vermiculite or perlite and one part sphagnum moss.
Step 2: Add the soil mix to the pot.
Step 3: Water your plant so the new soil is moist but not soaking. It should be more well-draining from here on out.
How to Aerate Your Plant by Making Vermicompost
A good compost pile can work wonders for your indoor garden. If your compost has earthworms, the worms will crawl through the soil and keep it light and airy.
Not all indoor gardeners are thrilled at the prospect of having live worms in their plant’s pot, and I can definitely understand that.
I would ask you to reconsider. Earthworms might be gross to you, but they won’t hurt your houseplants. I don’t consider them a pest at all, but rather, a beneficial friend to plants.
You’ll need a specific type of compost known as worm compost or vermicompost.
Here’s how to make vermicompost.
Step 1: Gather materials for your compost pile. Vegetable and fruit scraps are good, but dairy, oils, and meats are not. You want compost ingredients that the worms can digest quickly. If you do use fruit for your vermicompost pile, make sure it’s not citrus. All you’ll get are fruit flies, not earthworms.
Step 2: Put your materials in a container that measures 24 inches by 18 inches by 8 inches and is between 5 and 10 gallons. A shallower container works better for your purposes than a deeper one.
Step 3: Get some worms! Yes, this is the grossest part, but it will be worth it. You don’t have to dig up your yard looking for earthworms. You buy them online or shop at your local fishing supply store. Just make sure the worms are alive.
Step 4: With your worms ready, add them to your composting container. Close the lid and let the worms go to town. It can take anywhere from three to five months for the compost to be ready to use, so be patient.
Does Aerating Soil Damage the Plant’s Roots?
You were poking a pair of chopsticks into your plant’s soil and you hit something hard. Now you’re worried that instead of a clump of compacted soil that it was the plant’s roots you struck. It very well could have been.
You might do more than make contact with your plant’s roots during aeration, but break a root or two. A plant that’s in a healthy environment can regrow roots, but one that’s living in compacted soil cannot, at least not easily.
So yes, there’s some risk here, but the risk does not outweigh the reward.
It’s just like when you’d trim your plant’s roots. You’re removing the roots by aerating your plant too, just maybe a bit more vehemently. Your plant should be okay in the long run.
All that said, do make sure you’re being careful as you aerate. You want to try to minimize damage as much as you can.
How Often Should You Aerate Your Plant’s Soil?
Now that you’re aware of the importance of aerating your plant’s soil, you’ll want to make it a regular occurrence. Just how regular is up to you.
You should have your fingers in the soil often anyway to gauge when it’s time to water your houseplants. If you’re having a hard time getting your fingers in the soil, then compaction may have already started.
The goal is to prevent soil compaction rather than treat it when it’s underway. The threats to your plant’s livelihood from hard, compacted soil are too great!