Can You Use Compost Instead Of Potting Soil

Each thing has its unique characteristics. Whether potting soil or compost, they are prized in gardening for their unique properties. Compost as potting soil may be used, but it works best when combined with potting soil, perlite, river sand, etc., because every blend of compost will have a different pH, nutrients, and minerals as a drain in another way.

Even though potting soil is made explicitly for healthy plant growth, compost can improve the soil. This post will present an introductory presentation on the difference between compost and potting soil and their advantages and disadvantages.

In addition, you will be shown the direction of increasing fertility through the right perlite mix. First, we will review if It is possible to improve the compost quality by using compost instead of potting soil. 

Can You Use Compost Instead of Potting Soil?

New gardeners always think- can I use compost for potting soil? The answer, though, needs some critical explanation. Now when gardening with only compost without potting soil, it’s a matter to overthink. There are several restrictions on compost to be aware of, even if some plants can survive in compost for just a season or a few months.

  • Composts lack an ideal N-P-K ratio.
  •  Being entirely organic, it degrades and levels off over time.
  • Even there is no soil or sand to contribute root-friendly structure to the ground. 
  • Compost hardly offers the structural feature that potting soil usually features for plants’ long-term health and to assist their roots’ growth.
  • The pH of compost may be unknown and will vary for each mixture.
  • Compost may be too much dense and broken down further. It holds water for a long. Staying moist for long compost can rot the root.
  • Its organic material breaks down fast and drops in level over time.
  • It gets dried fast. Particles in compost created from several brown components, such as hay and bark mulch, will be spaced further apart.

The age of the said compost is another issue you could run into when planting directly into the compost—an illustration. For the first 40 days, a newly created compost heap will likely heat up significantly.

This implies that any new plants inserted into it will have their roots burned. Additionally, since the composting process has just started, newly created compost won’t include many nutrients.

Avoid planting anything in a fresh compost pile for at least 40 days because of these two factors. Therefore, it is not generally advised to just plant in compost. However, there are some situations where planting in compost without soil is nearly or minimally successful.

Now it’s to see how to overcome these limitations to some extent. Only a limited number of plants can compost and be used as potting soil. 

  • To give the compost the structure it needs to encourage plant root growth, combine 1:4 of the mixture with coarse river sand. It will aid in stabilizing the variety and slow down the rate of level descent.  
  • When using compost as potting soil, perlite is an excellent technique to increase the amount of oxygen and enhance drainage. 
  • Adding a handful of pelleted chicken manure will help slowly release nitrogen and other nutrients.
  • With potting soil mix, top up to improve its sand-less structure a bit more.

Now another question may come to your mind. What plants grow well in compost? Lists are-

  • Courgettes grow well as they love nitrogen.
  • Squash and Pumpkins: grow well.
  • Bell peppers grow well.
  • Hot peppers grow well.

The plant list that grows poorly in the compost follows as-

  • Cabbages and cauliflower: grow unhealthy
  • Parsnip and Carrots: sprouts quickly but with weak roots.
  • Potatoes grow but with insufficient tubers or scabby tubers for the over-rich nitrogen levels.
  • Beetroot: grows but produces small beets.
  • Tomato: grows well but tends to bolt and be weakened.

Is compost the same as potting soil? 

First, you must know their basic standings chemically or biologically to see that they are different. Most potting soils primarily consist of peat moss, bark, or perlite. Mostly, potting soil is steam sterilized to kill potentially pathogenic microorganisms.

Because it lacks mineral deposits and humus, potting soil is not indeed soil. Potting soils generally provide few nutrients because they are lifeless and devoid of minerals. To provide aeration and structural support for the root system, inert materials like perlite and rock wool can be used instead of soil.

Contrarily, compost is made from a variety of plant waste and is typically handled in a secure and covered place where it can gradually be supplemented with additional organic and vegetal plant debris, eggshells, coffee grinds, and the like.

It is made from organic matter and is mainly used to fertilize fields and soil. Chemical manures, whether natural or artificial, are concentrated chemical compounds. Due to the compost’s wild nature, its composition is relatively variable.

Difference Between Compost and Potting Soil

Can You Use Compost Instead of Potting Soil?

This would be the duel between organic compost vs. potting soil which is inorganic. To aid drainage, stabilization, aeration, and disease control, potting soil is a sterile inorganic mixture of peat and various ingredients, including sand, perlite, and vermiculite.

It’s made specifically for indoor plants; on the other hand, compost isn’t sterile. The majority of the material in pure compost is organic. Over time, this will oxidize and reduce the capacity inside your pots. Compost is a fantastic amendment, similar to peat moss, but it isn’t actual soil or, more specifically, potting soil.

Does potting soil have compost in it?

Not necessarily, but you can add compost to potting soil.

Can you mix compost with potting soil?

Yes. Though, the results are mixed, some good, some bad, as below. The benefits can be obtained more by removing the disadvantages by maintaining the correct ratio.

Adding compost to potting soil: pros & cons

By adding compost to the soil, you can get the following benefits.

  • Provides food for beneficial bacteria that aid in fixing nitrogen and promoting the growth of earthworms in the soil
  • Most completed composts have a pH between 6 and 8, roughly neutral. They maintain the soil’s appropriate pH range, which is helpful for plants to absorb nutrients, by being added on top of the earth.
  • The three most essential macro-elements that hasten plant growth are phosphorus (0.6-0.9%), nitrogen (1-2%), and potassium (0.2-0.5%), all of which are present in compost. Additionally, it has a few trace nutrients that synthetic fertilizers frequently lack.
  • The soil fungus and bacteria ward off different plant diseases that compost contains. Moreover, it reduces the need for hazardous pesticides and fungicides that harm people, animals, and even the soil biota.

Composting potting soil also causes specific hazards.

  • Rats and snakes frequently congregate around compostable food waste.
  • When specific food waste is used, it decomposes with an unpleasant stench that pollutes the air.
  • The process of breakdown involves bacterial activity and the transmission of several diseases.
  • If composting is adequately monitored, it requires both energy and time.

How much compost to add to potting soil?

Compost potting soil ratio is important plant-wise. Whether you rake or blend, after screening through an approximately 10mm sieve, ready your compost and potting soil blend for different purposes as-

  • Potted plants:

To blend from 4:1 to 1:1 blend (The higher the compost is, the more the moisture is held).

Rake and apply as 1:5 inches.

  • Flower gardens

To blend 1:4

  • New trees and shrubbery

To blend 1:9

  • Old trees and shrubbery

Rake and apply from 1:4 to 1:1 inches

  • Established lawns

Rake and apply from 1:8 to 1:4 inches

  • Seeding new lawns

Rake and apply as 1:6 to 5:11 inches 

Can old potting soil be composted?

Absolutely. Using potting soil is a beautiful addition to your compost if you follow simple rules.

  • You may destroy any pathogens in your old potting soil and any invading plant seeds that may have been sprayed across it by pasteurizing it.
  • Never attempt to reuse potting soil by adding it to the compost pile after a diseased plant has been there.
  • You can include vermiculite, liquefied seaweed, molasses, pre-rinsed coir, or vermicast.

How to compost the old potting soil?

Just have these simple precautionary steps executed while composting the old potting soil.

  • Place any potting soil you want to use again in your composting in black plastic trash sacks to get started.
  • After that, transport the bags to your yard’s sunniest area so they can bake there.
  • For at least a week, keep the sacks in their sunny location.

Composting old potting soil enables a gardener to have an enriched soil mix with no chance of contamination. In a considerably shorter period, the pasteurization of your compost pile can be easily achieved.

Advantage of adding old potting soil to compost

Since potting soil is pricey, putting used potting soil into compost is an excellent idea before discarding it.

  • This new organic fertilizer increases garden production by twofold!
  • The low-cost method f re-mineralizing your soil
  • Although it may be deficient in nutrients, it still has humus and perlite threads, making it perfect for covering recently potted lasagne, carrots, beets, and slow-sprouting seeds.

Vermont compost potting soil (review) 

For professional farmers, Vermont Compost Potting Soil can organically revolutionize farming productivity. It’s a nutrient-rich compost-based amendment offering a combination of minerals and organic matter to improve soil texture.

It feeds the soil so that your plants may proliferate well. It’s wisely blended for field and greenhouse applications with increased organic molecules, soil tilt, and nutrients. This amendment is perfect for reviving potted plants and never burns the roots.


But remember, confidence from “you may” does not mean “you should.” It should not be made into a rule. It is for limited scope only. As the human body can’t metabolize nutrients with only vitamins, a balanced diet with carbohydrates-proteins-fats is also necessary.

Similarly, a flat farming bed should be created by mixing compost with potting soil for plant health. Pursuing pure compost cultivation could result in unfavorable vegetative development and even promote early root disease.

Better follow the above guidelines to have better results by mixing compost with potting soil or old potting soil in the correct compost-to-potting soil ratio. After all, your experience of turning compost into the ground will remain good with gardening. To have an answer to “Can I use compost as potting soil?” may the knowledge of the advantage of adding potting soil to compost will grow your gardening skills.

The end

Similar Posts