Should you use potting soil or compost? (Gardeners Weigh In)


Many gardeners will visit the local big box store or nursery to find some soil or compost. With many products to choose from, it can be difficult to decide which one is the right choice for your garden.

It is best to use compost when there is a surplus of leftover food and items thrown into the landfill in your households, which can be utilized to lessen the use of chemical fertilizer in your plants and soil amendments. As for potting soil, these are commonly found in stores with a mix of organic and inorganic materials to aid in specific gardening needs.

Using either soil or compost has many benefits for your garden. We will be discussing the advantages and disadvantages to your garden when using either compost, soil, or both. To help you make the best decision possible for your garden, we explain the difference between soil types.

The only certainty is that that that to maintain the health of your garden, adding either soil or compost is always better than not adding anything at all. Compost and soil can be difficult to distinguish from one another, so let’s get into the differences and find out what’s best for you.

What are Compost and its use?

Compost is made using oxygen, water, organic materials, and bacteria to create a mix of decaying, nutrient-rich soil with medium density. Brown matter, such as dry leaves and twigs, and green matter, including lawn clippings and food, are combined as part of the process of composting and begin to deteriorate.

Before planting a new set of crops in the springtime, the materials are predominantly used to freshen up depleted soils after breaking down materials into rich soil.

Benefits of the use of Compost

Composted materials benefit the soil by loosening clay for optimal root penetration, aiding in water penetration, and provides microorganisms.

The nutrient-filled matter that composting provides reduces the need to use soil amendments and chemical fertilizers. It also reduces the number of leftover foods, fruit and vegetable peelings, and eggshells from ending up in landfill waste.

Compost Uses

Once it has completed maturing and is ready to use, there are many ways to use compost in your garden. You can use it to improve the quality of your soil by mixing it in; after you aerate your lawn, you can spread the compost over it, water down the compost tea, and use it as liquid fertilizer, you can improve the quality of your soil by mixing it with your compost, you can even spread it as mulch.

When using compost as mulch, you can create a two or three-inch layer on top of your garden beds once or twice a year—the same as you would with any other type of mulch.

You can also dig the compost through your soil, if the soil needs improving, down to about four inches deep. You can speed up the composting process by using an insulated bin designed to trap heat, this will allow organic materials and food scraps to break down faster in the composter, or you can add worms – also known as vermicomposting.

Water that has been soaking in composted materials is known as compost tea water. Some of the compost’s microorganisms, humates, and nutrients are leached into the liquid.

Instead of using water, you can add compost tea to help your soil and boost the nutrient levels, the humates in compost help plants in their ability to use the nutrients that are available in the soil, along with many other benefits.

I find that a real gardener is not a man or woman who cultivates flowers; they are people who cultivate the soil. They are a creature who digs themselves into the earth and leaves the sight of what is on it to us gaping good-for-nothings. They live buried in the ground. They build their monument in a heap of compost. If they came into the Garden of Eden, they would sniff excitedly and say: “Good Lord, what humus!”

Compost Types

Before applying compost, ideally, you should sieve it when using pure compost to topdress your lawn. To work its way to the soil, you would want the pieces to be as small as possible so the compost doesn’t sit on the top of your lawn.

The most common types of compost are:

Wood Waste Compost

Wood waste compost is primarily made up of bark chips, leaves and branches from when trees are pruned. It is piled up high and quickly heats up. Due to it’s carbon content this compost take a long time to break down fully into useable compost. It can however be used as a mulch before fully broken down.

Green Waste Compost

Green waste compost consists of all garden matter and kitchen vegetables and fruit scraps. It typically is left at the curbside, where it is collected by the local authorities and taken to a processing center. It is ground into smaller particle sizes and blended, and huge amounts of water are added.

Green waste compost is mounded high in long rows called windrows, and special equipment is used to turn this every couple of days to increase air which speeds up the breaking down process. A lot of bagged compost contain green compost in their formulations.

Manure Compost

Manure compost comes from herbivore manures. It is usually cow or horse in nature, but also alpaca, sheep, rabbit, goat, or any other animal that does not eat meat manures could be used. This is required to be left to continue rotting into compost.

Care must be taken to know where the manure has come from as certain animals have been treated with antibiotics, and the ground they feed on could have been treated with pyralid weed killer, a broadleaf weed killer. These can continue throughout the composting process and kill your plants when used to grow in

It is prudent to ask the source if these have been used on their land to avoid this issue.

Sterilized Loam

This type of compost is a combination of clay, sand, and silt. To ensure there are no undesirable organisms or chemicals, the combination is treated. There is usually a higher amount of silt and sand than there is clay within loam compost.

When To Use Compost

Compost is best if you’re looking to improve the quality of your soil. If you are putting many plants into one pot, such as during the summer when planting bedding plants, the plant won’t reach as many nutrients or spread its roots.

This is when you need something with more ‘oomph’ – that is, more nutrients, a slow-release fertilizer, and more organic matter.

To apply the nutrients into your soil, you can rake or till the compost to mix it into the soil. You can use this compost and soil mixture when planting flower beds, sowing seeds, installing sod, or planting shrubs.

The mixture of compost and potting soil is called potting compost and is used by many nurseries. This mix gives you the advantages of compost, more nutrients, and organic matter, together with the benefits of soil, because it holds a better structure and dries out slower.

To grow properly and allow them to grow better with the added nutrients, you may want to consider adding compost when growing plants that are classed as “hungry,” such as vegetables.

Compost Advantages

Uses of CompostBenefits of Use
Soil nutrient boosterHelps feed microbial life
Maintains a high level of natural health of the soilIncreases overall population and diversity of soil life
Beneficial microbes growthBuilds soil fertility, structure, and nutritional value of soil
Sufficient nutritional elements for soilNo chemical additives are required
Retains moisture in the soilCompost holds moisture in the soil like a sponge
Proper plant growth promotionMicrobial life increase nutrients, fungi helping plants to grow
Fights disease in the soilIncreases good bacteria that attack the bad bacteria
Controls and limits weedsWeeds prefer Barron, poor soil. wanted plants are stronger
Feeds soil directlyNo chemicals, organic matter increases fertility with microbes

It is much cheaper and environmentally friendly than fertilizers, both organic and non-organic, because you have the ability to make your own

Compost Disadvantages

  • We need to make sure that there are no soil-borne pathogens in any garden plants
  • It takes longer to see any effect in the soil compared to other additives
  • It Will be very time-consuming and can take months to break down properly
  • Unlike digging up some topsoil, making compost will require more physical labor.
  • It can be a bit smelly because it is made of decaying organic matter.

For further advantages and disadvantages of composting, I have a full detailed article covering this. It will take you through the entire subject so that you know what, when, and where to use and make compost.

What Is Soil?

Made from various proportions of clay, small amounts of organic matter, sand, and silt, the soil is found on the top layer of the earth. There are more than 70,000 types of soil.

To get nutrient levels back to an optimal level, you will want to amend the soil by adding new soil to it after several seasons of growing usage. Because of this, compost has become important. The top layer of soil, where everything grows, is called topsoil.

Topsoil is what you need if you are adding or replacing lawn, making new garden beds, or the soil already in your garden is shallow, or you’re putting in raised beds and need new soil added.

What Is Potting Mix?

It is important to understand what typically potting mix is what you will find in stores. There are various mixes that you will find to help you with your gardening efforts; for this section, we will focus on the potting mix.

Potting mix will usually contain organic and inorganic materials; they may also contain mineral soil and sand.

Many potting mixes consist of sphagnum moss, peat moss, and compost for moisture retention. To manage to drain without using mineral soils like clay or sand, vermiculite or perlite is used. This type of potting mix is labeled as “soilless.”

Many people have issues when deciding on whether to use potting mix or potting soil. This article will help you decide what to use in your circumstances.

Different Soil Types

To be a successful gardener, it is essential to have a healthy layer of topsoil. Topdressing your garden or lawn will lead to healthier growth if you purchase higher-quality topsoil.

Topsoil is available in three different types:

Clay Soil

This type of soil contains tiny particles that hold water and does not drain water as well as other types, soil that holds water holds water well doesn’t need to be amended as regularly since it can hold nutrients for longer.

Clay soil can be a cause for concern when growing in your garden. I wanted to tackle this and answer the question can you grow in clay soils. So I wrote an article to break this down and show you how to get the best results.

Loam Soil

Just like loam compost, loam soil consists of a mix of silt, sand, clay, and organic materials and is the best when it comes down to the level of nutrients. This is the perfect type of soil for adding topsoil to your garden or lawn due to its high nutrient and organic matter level.

Sandy Soil

With this type of soil, you will have to water and fertilize more frequently because it is the exact opposite of clay soil in nutrient and water retention.

Balance is key when it comes to amending your soil. Adding sandy soil is best when you need to improve drainage. Adding clay-based soil is ideal if your soil is not holding nutrients or water well. If you need to add the most nutrients possible, you should consider adding loamy soil.

How to make compost to add to your soil?

For some, compost can be a daunting task; they worry about how to make it effectively. You may have had experiences or heard for someone who had a slimy, smelly heap or one that never broke down. In the video below, I take you through everything you need to know in full detail so that you get perfect results every time.

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How To Make Compost - Composting Process - Compost Methods video

Is It Ok To Use A Mix Of Topsoil and Compost?

It is an excellent idea to use a mix of topsoil and compost; this will mean that your garden or lawn will benefit from both.

Due to its organic nature, compost has more nutrients but is more difficult to spread around your garden. A mix of both topsoil and compost will result in an easier to spread and more nutrient-rich combination.

You will start to see the benefits of your work several months down the line since that’s how long it can take for the nutrients in your newly added layer of topsoil or compost to reach down to the root system of your garden.

If you decide to buy compost out of a store, be sure to read the label and, based on the purpose of what you are using it for, decide which is best since store-bought compost will be more often than not a mix and not a pure compost.

Make sure to do your research when it is time to buy soil or compost. You can avoid problems from a poor quality product along with saving money and time.

When deciding whether you need compost or soil, here is the basic rule that you should follow:

  • General gardening = topsoil
  • Hungry or potted plants = compost

Adding soil or compost can surely be a regular practice; most people choose to add new layers every year or every other year. You would definitely want to top up at the beginning of every growing season to give your garden better-growing conditions no matter how thin you spread your soil or compost.

FAQ’s on potting soil and compost

Conclusion on Should you use potting soil or compost.

Adding potting soil or compost to your garden and deciding which is best to use is pretty straightforward, and following the information in this article, I know you can make the right choice for yourself. Remember, plants want to grow, and they will tell you if something isn’t right.

Become a student of your plants and watch what’s happening to them; little telltale signs will show themselves, and you can make the difference by altering your tactics whether your adding potting soil or compost, then know that your plant will grow as long as they have nutrients, water, and warmth.

As we have discussed, compost increases the microbial and fungal life in the soil. But it also increases worm density, and as we all know, worms are perfect for the garden. I wrote an article on how to increase the worm population in the garden to help you increase productivity.

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Tony O'Neill

I am Tony O'Neill, A full-time firefighter, and professional gardener. I have spent most of my life gardening. From the age of 7 until the present day at 46. My goal is to use my love and knowledge of gardening to support you and to simplify the gardening process so you are more productive

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