Understanding all the different types of soil, their primary characteristics, and what they should be used for can be a complicated task. When you buy a bag of garden soil, you might assume it’s ok to use it in your indoor containers. However, using soil meant for an outdoor environment for your potted plants is never a good idea, especially if you haven’t amended it.
Garden soil says “not for containers” because it’s only meant to be used outdoors. Indoor plant containers need a different ratio of matter than outdoor plants growing freely in the ground, and garden soil doesn’t make the cut. If you use garden soil in a container, your plants may not survive.
In the rest of this article, I’ll discuss what happens when you use garden soil in containers, the primary differences between container soil and garden soil, and whether you can mix the two together. I’ll also dive into the differences between garden soil and topsoil.
What Happens if You Use Garden Soil in Containers
It’s happened to us all: you accidentally used garden soil in your containers rather than potting soil thinking nothing will happen.
However, a few things could easily go wrong if you do so:
Plants Will Become Dehydrated or Die
Your container plants won’t get the correct amount of nutrients, good enough moisture levels, and oxygen. Potting soil made specifically for container plants has excellent aeration properties, making it easy for the plant’s roots to “breathe” within the soil and take in all the essential nutrients.
However, garden soil is extremely dense, so it will effectively drown your plant’s roots, depriving them of the oxygen they so desperately need. It’s also incredibly heavy compared to potting soils, so you’ll end up with dehydrated plants with dead roots.
Pests, Diseases, and Weeds Can Affect Your Plant
Using garden soil that hasn’t been appropriately treated might even bring in unwelcome diseases, insects, and even weed spores. All three of these things will bring their own problems. But weed spores, in particular, will drain your containers of all the nutrients, taking away everything the plant needs to survive (and thrive).
Garden soil is labeled as such because it is made for outdoor use in gardens. It isn’t made of the same materials as potting soils, so it doesn’t have the capacity to care for your indoor plants in quite the same way as potting soils.
Why Potting Soil Is Best for Containers
If you’re still not sure why you shouldn’t be using garden soil in your containers, here are some reasons why potting soil is best for potted plants:
Potted Plants Require Specific Soil Nutrients and Texture
Garden soil, on its own, does not have the required level of nutrients that container plants likely need. This means garden soil would need to be mixed with other soil additives in order to be even slightly beneficial for indoor potted plants.
Potting soils are not made with any soil from the garden. This is the biggest misconception with container soils, and many people have no idea this is the case.
Garden soils are typically made of topsoil and soil additives like wood chips, compost, or peat moss. However, potting soil is usually made of natural soil additives—with or without actual soil.
This is precisely why your garden soil says it shouldn’t be used in containers. The stuff you use to fill up your pots is fundamentally not the same thing as garden soil—and is made of only natural, earthy necessities that your container plants really need.
Moreover, garden soil is an additive that can be utilized with soil that’s native to your garden. That means it is primarily built to enhance the soil environment in your garden—not in your containers.
It is made to accommodate the very specific needs of your outdoor plants growing freely in the ground. It isn’t meant for plants trapped inside small environments since it’s not a good aerator and doesn’t provide adequate moisture for plants that need it.
Various Potted Plants Have Specific pH Needs
The pH of garden soil can be very different from potting soil. Potting soils are typically made with specific plants in mind, meaning, they often have a very specific pH.
In contrast, commercial garden soil needs to be mixed with other things, such as compost or peat moss, both of which invariably contribute to pH levels.
How to Amend Soil for Container Plants
You can mix potting soil with garden soil – but you might destroy your plants in the process.
Let me be clear: mixing garden soil with other soil additives may well work for you and your plants, especially if you’re being very careful about what additives you are using. However, if you’re not careful, you’ll offset the balance of your pretty indoor plants and end up with dead roots.
A good rule of thumb to follow is to refrain from using garden soil without adding any other essential materials, such as sand. It will inevitably affect your plants’ growth, and you’ll end up with a very sad-looking container.
Modifying garden soil by mixing it with potting soil and another soil amendment might work well for you, especially if you’re in a situation where you don’t have enough potting soil to fill your container.
Be mindful that this will only work when using a larger container. If you’re using it for a little pot, it will likely kill your plant’s roots very quickly.
Using a 1:1:1 ratio is usually the best way to modify your garden soil to turn it into an acceptable growing medium for a container.
That means the following:
- One-third garden soil
- One-third potting soil
- One-third soil amendments, such as compost, peat moss, or sand.
Amending garden soil might improve the environment for your container plants, but this isn’t guaranteed. There’s always a chance the garden soil has an insect infestation or weed spores, and it might still be far too dense for your delicate plant roots to fully take in all the nutrients they need.
If you’re afraid of the garden soil being too dense for your container, one of the best ways to ensure good aeration and drainage is to check the holes in the bottom of the container.
If you’re adding garden soil to the mix (as a last resort, hopefully), you can make the holes slightly bigger to provide a better drainage system for your plant. This will hopefully mitigate the risk of the soil smothering your roots and killing them.
Alternatively, if you can’t fix the soil drainage in the container, you can always include a bit of perlite to improve drainage.
Garden Soil Is Not the Same As Topsoil
You might think that garden soil is the same thing as topsoil, which is understandable. However, this is a common misconception.
Garden soil is not the same as topsoil. Garden soil is, in its natural state, the same as topsoil—but when it is sold in bags, it means it has been treated with organic materials to make it better for plant growth. Topsoil is just the name for the top few inches of natural, untreated soil.
When garden soil is treated, a plethora of nutrients and additives are added to create a mixture that has been primed specifically for gardening purposes. Usually, it has gone through a vetting procedure to ensure that plants can thrive in it.
Conversely, topsoil often contains its natural, decomposed organic matter, such as dead plants, leaves, and insect remains, but it hasn’t been chemically treated or processed in any way. It often contains plenty of weeds, which aren’t great for your plants since they leach out all the nutrients the plants need for survival.
Topsoil is also usually one type of soil, whether clay, sand, loam—or something in between. It’s generally unlikely to find topsoil in one area that is two different types, and it often depends on the area in which you live.
“Garden soil,” as it states on the package you bought, is a unique mixture of various types of soils to accommodate specific plants with particular characteristics and needs.
Your garden soil says it shouldn’t be used in containers because it is far too dense for your container plant’s delicate roots. It doesn’t provide the correct nutrients (and soil balance) like potting soil does, and garden soil drainage and aeration systems may not be appropriate for smaller, indoor settings.
Mixing garden soil with container soil is acceptable in a pinch – as long as you do it in the correct ratio. Putting too much garden soil will inevitably decrease aeration levels, risking suffocating your plants’ roots.