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What’s the difference between topsoil and potting soil? The choices can get overwhelming at the gardening center, but it simply boils down to what you’re using it for. Do you want fill in a hole? Do you have clay soil? Are you growing in a container? Learn more.
We run a greenhouse business. This past spring, due to supply chain issues, we could no longer get the excellent compost-based potting soil we have been using for years. We went from buying it by the bag to getting it by the truckload and our plants thrived on it. We called it the not-so-secret secret of oursuccess.
One trip to the garden center and we couldn’t believe the range of options. Suddenly, we found ourselves with the dilemma faced by many gardeners. What’s the difference?
What isTopsoil?
First, let’s talk topsoil. It’s very name says it all. Topsoil is the soil scraped from the top of the ground. It’s what you find naturally in youryard.
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Topsoil is not sterile so it often has viable weed seeds and can harbor disease pathogens and fungalspores.
On the plus side, it contains naturally occurring nutrients and minerals, and beneficial soilmicrobes.
It’s very heavy, often containing a large amount of clay which makes it hold water. This can be a good thing, lessening the frequency of watering or a bad thing since the soil stays soggy and doesn’t drain well. It tends to pack down, making it difficult for seedlings toemerge.
High-quality topsoil should have a loose texture that crumbles like cake between your fingers and not clump up. If you have poor-quality topsoil (often too much clay), then buy enriched topsoil. This is a mix of topsoil with organic matter such as compost, sand, or compostedmanure.
Not that topsoil is only only for outdoor use such as spreading on your lawn when planting grass seed to get grass off to a good start. Use it to fill in and level low spots and add it to outdoor plantingbeds.
Also, buy topsoil for raised beds if your own topsoil is poor. Mix in organic matter such as compost to improve drainage at a 2:1 ratio of topsoil to compost. Or, purchase the enriched topsoil already mixed with compost. Over time the quality of the soil below the raised bed willimprove.
What is PottingSoil?
Potting soil (also called potting mix) often contains no soil at all, hence the name soil-less mix on many bags. It is usually based on peat moss or some other quick draining material and sometimes has compost or biochar mixedin.
Potting soil is lightweight, has lots of air in it so water runs through quickly and it will not pack down. Perlite and vermiculite add even more air space, making it light and fluffy. Ingredients are listed on thebag.
Soilless potting soil and potting mix are best for containers since they need good drainage. Look for even fluffier seed-starting mixes when planting seedsindoors.
We tried 6 different kinds of potting soil and liked this one thebest.
Choosing Between Topsoil and PottingSoil
The choice between topsoil or potting soil comes down to what you’re using itfor:
Topsoil is for landscaping and outside uses. It is heavier and cheaper and is not sterile. If you are filling a hole or leveling out the ground, just get regular topsoil. (Or, sometimes you can find “fill dirt” from construction projects but only use if you are reasonably certain it is free of soil-borne diseases, pests, andcontamination.)
Enriched topsoil (topsoil + compost) is for actively growing plants. Garden beds, shrubs, and trees all need a rich layer of minerals and organic matter. Plan on 6 to 8 inches of topsoil. Grass lawns also need topsoil though grass is shallow-rooted so 4 to 6 inches of topsoil isample.
Soilless potting soil aka potting mix is for containers and indoor use. It is sterile, lightweight and more expensive. If you’re planting in pots, use pottingsoil.
Can You Mix Topsoil With Your PottingSoil?
Potting soil can be mixed with topsoil for particular cases such as raised beds (though we’d recommend 50% topsoil/compost for raised beds), but topsoil is a bad idea for containers. This defeats the entire purpose; potting soil is specifically formulated to be “soil-less” and provide the light mix for drainage and root development in pots. Adding topsoil makes the soil dense and heavy, and not good for watering which is critical forcontainers.
Hopefully, next time you visit the garden center for soil, it won’t be sooverwhelming!
The choice between topsoil or potting soil comes down to what you're using it for: Topsoil is for landscaping and outside uses. It is heavier and cheaper and is not sterile. If you are filling a hole or leveling out the ground, just get regular topsoil.
The choice between topsoil or potting soil comes down to what you're using it for: Topsoil is for landscaping and outside uses. It is heavier and cheaper and is not sterile. If you are filling a hole or leveling out the ground, just get regular topsoil.
Do not use topsoil alone in containers. It can become compacted and saturated with water limiting air space that is important for healthy plant growth. Topsoil is occasionally added to potting mixes in large containers for increased moisture-holding and added weight needed to support large plants.
The best soil for gardening is well-draining but moisture retentive. While loamy soil is ideal for most plants, it's important to keep in mind that different plants thrive in different types of soils. For example, succulents need sandy soil, and certain trees and shrubs thrive in clay soils.
Can You Use Garden Soil as a Substitute for Potting Soil or Vice-versa? Yes, you could use either garden soil or potting soil to grow outdoor plants. However, potting soil is a better choice as a growing medium as it's specifically created to support plant growth.
Clean topsoil or garden soil can be used and should be sterilized to kill disease organisms and weeds. Spread soil in a tray and bake at 200º F for twenty minutes, stirring every five minutes. Sand adds air space to a potting mix. Builder's sand, or coarse sand, is best.
Potting Mix vs Potting Soil: Which One Should You Use? Potting soil's composition makes it suitable for outdoor plants. On the other hand, a soilless potting mix is a better choice for potted plants or a container garden because it: Offers a good balance of moisture retention and water drainage for potted plants.
Inexpensive bagged topsoil is rarely any good. In my observation, it is usually composed of poorly composted wood chips, silt, and sand. This mix will not support good plant growth. In addition, having different layers of materials in your raised bed will make for a very poor rooting environment.
Potting soil isn't actually soil, because it doesn't have any humus and minerals. That's why it's sometimes labeled "potting mix." Some of the best potting soils contain fertilizer, but if yours doesn't, it's easy to add a granulated all-purpose fertilizer when planting.
When growing plants in containers or raised beds, you need to pay special attention to the soil you use. Soil taken from your yard or a garden bed is too dense to use in a pot or raised bed. Instead, for containers, you'll want to use potting mix (also called potting soil), a lightweight and fluffy alternative.
Yes, you can mix the two if you'd like to use topsoil for your container plants or raised beds. Mixing them will enhance the topsoil's structure, making it more viable for potted plants. Additionally, topsoil's high organic content will add nutritional value to the potting soil.
You want to use far more garden soil than potting mix, around a 5:1 ratio. You can also make your own raised bed mix by mixing all the individual parts of garden soil and potting soil, so topsoil, bark or peat, compost, and perlite or vermiculite.
The main disadvantage of potting soils is that it can be expensive, while soil from your own garden is free. Some plants can be harmed by a potting mix intended for another type of plant. Also, some potting mixes are not suitable for organic gardening because of synthetic ingredients they contain.
Potting mix is meant to stand alone, as opposed to being mixed in with existing soils. It is a self-contained product designed to provide potted plants with everything they need to grow and thrive. Garden soil is meant to be spread around. Mix garden soil in with your native dirt to improve it.
The best topsoil for growing plants is loamy soil. It is a mixture of sand, clay and another type of soil particle known as silt. Silt occurs as a deposit in river beds. The size of the silt particles is between those of sand and clay.
Unfortunately, potting soils can be quite pricy, while the garden soil is free. Plus, potting soil usually does not contain many organic materials, so ensuring plants are getting the nutrients they need requires extra attention.
Can You Grow Grass in Potting Soil? The simple answer is no, outdoor grass will not grow in potting soil. Potting soil is best for planting indoor grasses or plants in pots or containers. Instead, you should use topsoil to grow grass in your lawn or other outdoor areas.
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