Potting soil can get expensive and sometimes it’s tempting to try and use garden soil that may be cheap or free. But what problems could this cause for your plants?

Garden soil will not kill your potted plants if it’s healthy but your plants won’t grow well. The texture and contents of the garden soil may cause a lack of moisture, nutrients, and aeration. The garden soil will kill your potted plants if it contains harmful chemicals, pests, or diseases.

I’ve written more details below on why garden soil may harm your potted plants. I’ve also provided some solutions to use garden soil for the potted plants and save some money.

Garden soil may cause a lack of moisture and aeration

I find the biggest issue that can happen with garden soil is the texture. It contains a lot of sand and clay that makes it heavy.

A lot of sand means the soil will drain moisture fast causing underwatering issues. If the garden soil contains a lot of clay, the moisture won’t drain well causing overwatering issues.

In both situations, the roots won’t get the required moisture and oxygen from the soil. They won’t be able to supply the same to the plant which will harm it. 

Garden soil may not contain the required nutrients

The garden soil may contain clay or sand and not enough nutrients that plants would need.

When you grow a plant in a pot, the roots can’t spread to get the nutrients. So you are responsible for providing them the nutrients they need.

If you use the garden soil for the potted plant, there will be a lack of such nutrients, causing poor growth and even death.

Garden soil will not kill potted plants, but potted plants need more nutrients than just garden soil. Mix with a good fertilizer when adding the soil to your pot. Then sprinkle compost on top every week and you are good to go. – Ja-ne de Abreu, Sassy Food

Garden soil may introduce harmful chemicals

The garden soil may contain chemicals that can harm your potted plants. These chemicals may have been introduced when the garden was sprayed with pesticides, insecticides, or fertilizers.

Some of these chemicals can kill your potted plants. If you’re growing edibles in the containers, it can harm you as well.

You may not know what types of chemicals are present in the garden soil before using it. A soil test would be helpful to understand such issues with the garden soil.

Garden soil can harbor pests, diseases, and toxins. Potted plants are far better off with clean, healthy potting soil that is specifically formulated for proper water and nutrient retention. – Kate Russell, The Daily Garden

Garden soil may contain pests and diseases

Garden soil may contain harmful pests and diseases that will attack and kill your potted plants.

You may not see pests or diseases in the garden soil because of its small size. But you may introduce them directly to the potted plants where they can grow and spread quickly.

Can garden soil be used for potted plants?

Garden soil can be used for potted plants as long as it’s healthy and free from pests, diseases, and chemicals. You need to mix it with the right amount of potting soil before using it for the potted plants.

You can save yourself some money by using garden soil for your potted plants. If you buy the garden soil from a nursery, you can ensure that at least it’s free from pests, diseases, and chemicals.

But if you’re using garden soil from your outdoor garden, you should get a soil test done first. The soil test will show you if the garden soil contains harmful pests, diseases, or chemicals.

You can get this test done from your local extension service for a small fee. The test will also show if you can amend the garden soil and make it better.

I recommend you do not use the garden soil if there are harmful chemicals found in it. But if it’s a problem of pests and disease you can still make it usable.

You’ll need to sterilize the garden soil before using it for the potted plants. The easiest way to do this is to heat the soil in an oven at 120 degrees for an hour. You can mix it with the potting soil after it has cooled down.

The heating of the garden soil at such temperatures will kill the harmful pests and diseases making it usable.

You can mix these together and make your own mix to save money but make sure you don’t mix too much soil (or heavy soil) with the potting mix otherwise it might make the overall mix too heavy and anaerobic (without oxygen). – Mark Valencia, Self Sufficient Me

Now you need to mix it with the potting soil so the final mix is suitable for growing potted plants.

The simplest way to do this is to mix 1/3rd garden soil, 1/3rd potting soil, and 1/3rd compost and add that to the pot. If you have a really tight budget, you could mix 50% garden soil with 25% potting soil and 25% compost.

The best way to do this is to spread the garden soil on a tarp. Then pour the required amount of potting soil.

Spray a little water on the materials so it does not cause dust as you mix it up. Use a shovel to mix the garden soil and potting soil.

This combination of garden soil and potting soil will help the soil get the right texture. It will absorb the required moisture but drain out the excess. The airflow will be good in the soil so the roots get the required oxygen. 

Typical Potting Mix Contains: decomposed/woody material (around 50-65%) spaghnum peat moss (or equivalent) (prettypurpledoor.com)

Can I use all-purpose garden soil for indoor plants?

You can use all-purpose garden soil for indoor plants but you need to combine it with potting soil. You can use 50% all-purpose garden soil and 50% potting soil to grow indoor plants. The combination will provide the right soil texture that retains sufficient moisture but drains out the excess.

The benefit of using all-purpose garden soil is that you know it’s free from chemicals, pests, and diseases. So it won’t end up harming the potted plants that could happen when using regular garden soil.

The all-purpose garden soil may also contain slow-release organic fertilizer to help the indoor plants get the required nutrients for several weeks or months.