Knowledge, Membership, Planting


In permaculture, the soil is considered the most important asset. Healthy soil is a prerequisite for a healthy plant. The requirements for a substrate for container plants are much higher than for plants that are placed in the bed since only limited root space is available. Therefore, let’s take a look at what properties a good soil actually needs to have.

What is the composition of soil in nature?

soil composition


Organic substances consist of:


Roughly divided, garden soil is composed of solid matter, water and air. For plants, the 7 % of organic substances are especially important. Organic substances improve the soil and provide a nutrient base for plants. A humus-rich soil is a prerequisite for optimal plant growth.


„Humus“: Inanimate organic matter composed of dead plants, roots, and soil organisms, which is constantly, rebuilt and decomposed.

The most common soils in Germany’s gardens are clay, loam and sand soils. Heavy clay soils are not very permeable to air and water and should be loosened before planting. Light sand soils store water and nutrients poorly, dry out quickly, and heat up considerably in the sun. Loam soils are ideal for flower beds.

The good thing about balcony gardening is that we are independent of the quality of the garden soil!

What different substrates are there?

Surely it has happened to you once as well. You were in the garden center or hardware store and wanted to buy soil, and found yourself in front of an enormous selection of different substrates: potting soil, plant soil, growing and herbal soil, just to name a few. What is actually their difference?

Focus is on

Consists of

Potting soil

Water storage and nutrient supply (optimized for flowering and ornamental plants)

For water storage and nutrient supply (optimized for flowering and ornamental plants)

Peat (or peat substitute), compost, NPK fertilizer and additives, such as perlite, clay minerals and/or quartz sand

Plant soil

Soil improvement: coarser structure and fewer nutrients than potting soil

For soil improvement: coarser structure and fewer nutrients than potting soil

Peat (or peat substitute), compost, NPK fertilizer and aggregates, such as clay minerals and/or quartz sand.

Growing and herbal soil

Root growth

For root growth

Peat (or peat substitute), little compost, little NPK fertilizer, aggregates, such as perlite or quartz sand.

„Substrate“: Usually industrially produced mixture of various mineral and organic starting materials used for growing and cultivating plants.

„NPK fertilizer“: Fertilizer that contains at least the three nutrient elements nitrogen (N), phosphate (P) and potassium (K).

Which requirements does the "optimal" ground have to meet?

Good water and nutrient storage capacity

Nutrient supply

Loose structure that allows good aeration of the roots and drainage of excess water

Structural stability

Free from weed seeds and germs

Unfortunately, these qualities are difficult to extract from the packaging of commercially available substrates!

The thing with peat

Peat is an organic material formed in bogs from the deposits of dead plants. Peat cutting destroys the habitat of numerous plants and animals and releases large amounts of CO2. Peatlands can store twice as much CO2 as forests and therefore play an important role as CO2 reservoirs. For this reason, you should definitely avoid peat to protect the environment and climate! Also avoid peat-reduced soil, which can contain up to 70% peat. Even an organic seal is not an indicator for peat-free soil!

Peat substitutes

To obtain an optimal substrate, combine the beneficial properties of several peat substitutes.


Compost can either be home-made or purchased (e.g. from composting plants). 

Bark humus

Bark humus is crushed bark mulch from conifers that has lost its growth-inhibiting substances through fermentation.

Wood fibers

Wood fibers come from coniferous residues from the wood processing industry.


Coir consists of dried bark of coconut palms and shredded coconut shell and is a waste product.

Coir dries out relatively quickly on the surface. First, check the moisture of the soil at a depth of 3-5 cm with your finger or a wooden stick before watering.

Why mix soil yourself?

When mixing your own soil, you know 100% what is in the substrate. You can respond individually to the needs of your plants and provide them with nutrients in sufficient quantities over a long-term period. You can also use materials that you already have at home, such as compost or garden soil. Substrates in garden and hardware stores are often stored on the outside. Since the bags are not completely sealed, germs and spores quickly intrude, causing mold during cultivation, for example. A quality substrate is important because it protects plants from diseases and pest infestation! A great advantage of coir bricks is that they do not entail lugging and storage problems! Due to compact units, coir bricks are also easy to use up, so sterility is not compromised in contrast to opened substrate packs.

What is a good soil mix for my balcony garden?

  • Min. 1/3 Coir

Good water storage capacity

Good aeration and drainage

Structural stability

Free from weed seeds and germs

  • 1/3 Compost

Good water storage capacity

Nutrient supply

Good aeration and drainage

  • Max. 1/3 Vermiculite, Bentonite or Perlite

Good water and nutrient storage capacity

Good aeration and drainage

Add more or less compost depending on the nutrients needed by the plant.

Potted plants: To activate soil processes and metabolic activities in the limited soil space, you can „inoculate“ the substrate with EM-A, or add garden soil or worm humus.

„EM“: Effective Microorganisms (EM) are a concentrated mixture of beneficial microorganisms, bacteria and fungi that activate soil life, promote root development and strengthen the plant. EM-A(ctive) is an activated and ready-to-use solution made from water, Effective Microorganisms primary solution, and sugar cane molasses, among others.


Compost, also bokashi „compost“, contains all necessary macro- and micronutrients. The exact composition of the nutrients depends on the type and composition of the organic waste. For example, in bokashi, waste is fermented, which creates additional vitamins and enzymes. The ideal C/N ratio for organic matter is 25:1. Deficiencies and imbalances can be avoided by mixing as diverse as possible. You can find more about C/N ratios of different ingredients of compost here.

„C/N ratio“: Parameter for the degradability of organic substances. The C/N ratio indicates how much carbon is contained in the organic substance in relation to nitrogen. The higher the C/N ratio, i.e. the more carbon, the longer the conversion takes. In addition, since microorganisms require nitrogen for conversion, nitrogen can deficits occur in carbon-heavy material.

Which additives can I use?

Mineral additives or soil additives improve the structure of the substrate. 


Perlite is an inorganic, volcanic glass that is expanded by heating to form a porous, airy grain. As a result, it reaches a multiple of its original volume. For soil improvement mainly perlite with grain size 0-6 mm plays a role.


Vermiculite is a naturally occurring silicate formed by the weathering of rocks and minerals. Through heating, the mineral is puffed to a multiple of its original volume. Relevant is especially the grain size of 0-5 mm.

(Primary) Rock dust

The composition of (primary) rock dust varies depending on its place of origin. Primary rock dust consists of fossilized lava (e.g. basalt) originating from „primeval“ volcanic eruptions and generally contains more nutrients than rock dust. Rock dust is made up of a mixture of rock types (e.g., quartz, zeolite, granite). As a clay mineral, bentonite, a primary rock dust, has additional water- and nutrient-storing properties.

(Primary) Rock dust can do much more. Added to compost and bokashi, it promotes the activity of microorganisms. It can also be used in pest control by dusting leaves and soil around affected plants. In addition, (primary) rock dust suppresses odors in slurry and bokashi.

You want concrete information, step-by-step instructions and mixing ratios of different substrates? 

Hi, I’m Lisa from Permapot. I’ve been growing my own vegetables in my small urban garden and on my terrace for 4 years now. With Permapot I would like to make it easier for you to get started with urban gardening!


By entering my e-mail address, I agree to the privacy policy. Unsubscribing from the newsletter is possible for me at any time with just one click.

Sichere dir deine Ernte mit 10% Rabatt!

Melde dich für unseren Newsletter an und erhalte 10% Rabatt auf deine erste Bestellung.

Mit der Eingabe meiner E-Mail-Adresse erkläre ich mich mit den Datenschutzbestimmungen einverstanden. Eine Abmeldung vom Newsletter ist mir jederzeit mit nur einem Klick möglich.