Potting soil, also known as plant substrate or simply substrate, is in contrast to naturally grown garden soil a man-made mixture of different ingredients. These soils are tailored to the needs of houseplants and other potted plants. The following article reveals which soils are available and how you use them.

The composition of potting soil varies depending on which flower it is to be used for

Table of Contents

Show all
  1. the essentials in brief
  2. What is potting soil?
  3. Types of potting and potting soil
  4. peat or compost?
  5. This is how you recognize high-quality potting soil
  6. Store potting soil properly
  7. Mix the potting soil yourself
  8. frequently asked Questions
  9. Can I also fill topsoil in the flower pot?
  10. The potting soil molds. What should I do now?
  11. Mushrooms are suddenly growing out of my flower pot. Is this bad and what can I do about it?
  12. The potting soil in the freshly opened bag stinks. is she bad

    13. the essentials in brief

    • Potting soil is fine, loose soil with a pH between 6 and 7, which is usually mixed with slow-release fertilizer.
    • There is special soil for many flowers such as hydrangeas, geraniums or roses because they have special requirements.
    • Buying potting soil with peat should be avoided for ecological reasons.
    • Potting soil can be made from garden soil and compost.

    What is potting soil?

    Pot and balcony plants need a suitable substrate in the pot, because without it they will not grow. It is important to rely on a high-quality product, because the plants are completely at the mercy of the material and its ingredients - in contrast to plants in the garden or even in the wild, which let their roots grow where there are nutrients and water are.

    Houseplants, which are usually only repotted every few years, are particularly dependent on good potting soil. This must be strong enough for the plants to find a hold in it, but at the same time to be able to store water and nutrients and release them again when needed. In addition, a potting soil is optimally composed in such a way that it neither hardens nor silts up. Normal garden soil is usually not suitable for this purpose, as it often has the wrong composition and is not fine enough.

    Potting soil or potting soil?

    Although the terms potting soil and potting soil are often used synonymously, there are some subtle differences:

    potting soil potting soil
    for pots, tubs and flower boxes for planting perennials or shrubs in the garden
    sole substrate Soil conditioner and compost substitute
    usually mixed with long-term fertilizer coarser structure, contains less fertilizer

    In principle, you can of course also use potting soil for your potted plants, but you should then add additional components such as a long-term fertilizer and, if necessary, some quartz sand for a finer structure. Conversely, potting soil is also suitable for use in the garden bed, but you probably won't choose that. High-quality potting soil (or potting soil) is often more expensive than potting soil.

    What is the pH of potting soil?

    With the exception of special soils, which are adapted to the needs of ericaceous plants and therefore have an acidic pH value in the range between 4 and 5, normal potting soil is brought to a neutral pH value between 6 and 7. Because many of these soils are made from acidic peat, manufacturers add lime and/or quartz sand. Most plants grown in pots and other containers grow best at a neutral pH.

    The ideal pH of potting soil varies depending on the needs of the plant

    digression

    Plant substrates without soil

    However, potted plants do not necessarily need potting soil for healthy and beautiful growth. Instead, you can also place the plants in so-called plant granules, which usually consist of small clay balls. This procedure is mainly - but not only - used in hydroponics and has many advantages compared to soil culture. For example, plant granules are cleaner, free from mould, rotting bacteria, pests, weed seeds, etc., so that expanded clay (€19.73) and Co. are ideal for allergy sufferers. In addition, the material stores large amounts of water without clumping or causing the plant to suffer from waterlogging. Instead, the moisture is released exactly when it is needed.

    What types of potting and potting soil are there?

    In the garden specialist center there is a huge range of different potting soil, so that you are standing in front of it and cannot really decide. After all, which soil is suitable for your own project? The following overview is intended to help you with the decision-making process.

    potting soil ingredients purpose of use
    potting soil Peat or compost, lime, fertilizers, aggregates garden
    unit earth White or raised bog peat, loam or clay, fertilizers garden and tub culture
    compost soil compost-based peat-free soil with aggregates garden and tub culture
    Universal Earth depending on the variety, based on peat or humus with fertilizers and additives for all potted plants, vegetable plants, herbs, fruit trees
    potting soil depending on the variety, based on peat or humus with fertilizers and additives universally usable for all indoor and balcony plants
    orchid soil coarse substrate made of bark, coconut fibers and peat Special soil for orchids
    Cactus and succulent soil high proportion of quartz sand for drought-loving cacti and succulents
    rose soil Often contains a lot of clay and a combination of nutrients tailored to roses for roses in the garden and in pots
    hydrangea soil loose, humus-rich substrate with an acidic pH value Different varieties for blue and other colored hydrangeas
    geranium soil Special mixture with a high long-term nutrient content for geraniums and other heavy-duty potted plants
    herbal soil loose, nutrient-poor substrate with a high proportion of quartz sand for many herbs and other plants with low nutrient requirements
    potting soil loose, nutrient-poor substrate with a high proportion of quartz sand for sowing and for cuttings
    Rhododendron and bog soil nutrient-rich, lime-poor special soil with an acidic pH value for rhododendrons, azaleas, hydrangeas, blueberries, lingonberries and cranberries

    Do you absolutely need all these special soils?

    In view of all these special soils for roses, hydrangeas, cacti, geraniums, etc., many a hobby gardener wonders whether they actually make sense or whether a normal potting soil does not also serve its purpose. In fact, some special soils are basically superfluous, as the needs of the respective plants can also be met with conventional potting soil. You can save yourself expensive rose or geranium soil, for example, both types thrive very well in normal, humus-based potting soil.

    The situation is different, however, with soils that are intended to meet the very specific needs of certain species. So rhododendron and bog bed soil is suitable for all plants that prefer an acidic environment. Cacti and succulents, on the other hand, need a rather dry and nutrient-poor substrate, while orchids do not tolerate potting soil at all. These feel most comfortable in a coarse substrate made of pieces of bark and other fibers.

    peat or compost?

    Many potting soils are based on the natural raw material peat. Although this is biodegradable, it is nevertheless extremely problematic for both the plants and the environment for various reasons.

    "More or peat bogs bind four times more carbon dioxide than tropical forests."

    • Drainage of peat bogs: Peat bogs are valuable habitats worthy of protection that provide a home for many rare plants and animals. In addition, these ecosystems, which have become rare due to urban sprawl and intensive agriculture, store climate-damaging carbon dioxide. If the moors are now drained for the purpose of peat extraction, not only is an invaluable ecosystem destroyed, but huge amounts of fossil CO2 are released at the same time.
    • depletion of peat deposits: Due to the drastic decline in peat bogs and the peat extraction that is still taking place, the reserves will be exhausted within a few years. For this reason alone, more sustainable alternatives should be sought and found.
    • Disadvantages for potted plants: In particular, the cheap "no-name" potting soil from the discounter is largely based on peat or peat waste. Don't use these soils, you're doing your plants a disservice. Peat-based potting soil tends to become rock hard when dry and then hardly able to absorb any water. The roots cannot grow unhindered and are also prevented from absorbing water and nutrients.

    In view of these disadvantages, it is important to use peat-free potting soil. But what are the options?

    This video presents the disadvantages of peat and a possible alternative:

    youtube

    What is peat-free or peat-reduced soil?

    There are several ways to replace peat in potting soil, either in whole or in part. For a number of years, for example, potting soil based on coconut fibers has been quite common in hardware stores and supermarkets. This usually comes as an ultra-light packet, to which water is added at home and which then swells and can be used.

    The rapidly renewable raw material coconut is therefore extremely user-friendly, but has come under criticism for ecological reasons. After all, the dried coconut fibers have to travel a very long way to Germany, which in turn causes carbon dioxide. Coconuts are also grown on plantations that have had to make way for rainforests.

    Compared to coconut fibers, the xylitol obtained as a by-product of charcoal production does not cause any additional environmental pollution. The material for use in potting soil was only recently discovered and shows extremely positive properties with regard to the growth and flowering behavior of potted plants. Xylitol soil is characterized by a very high air permeability and contains a similar amount of humic acid as peat soil. This keeps the pH of the flower substrate at an evenly healthy level.

    What is compost?

    In addition to the peat substitutes mentioned, compost is also a very suitable plant substrate for many potted plants. This also has the advantage of being absolutely environmentally friendly, after all it maintains the natural cycle of life and turns organic waste into a valuable source of nutrients. But be careful: do not put your potted plants in pure compost, but mix one part mature, finely crumbly compost and two parts of processed, clayey garden soil. Alternatively, you can buy suitable compost soil in the garden center.

    Compost is eco-friendly, nutritious and, at best, free

    How do you recognize high-quality potting and potting soil?

    Whether a potting soil is good or not can hardly be determined without opening the bag. In addition, you will often only find out whether it is high-quality soil during use - i.e. when your plants are already in it. If your houseplants and other potted plants are growing splendidly, blooming profusely and otherwise appear healthy, the potting soil is basically fine. Otherwise, please pay attention to these features when purchasing:

    • Buy peat-free soil.
    • Leave the fingers of cheap potting soil from the discounter.
    • This contains too much salt as well as too many fillers and will damage your plants.
    • Give preference to mixtures of biological raw materials.
    • This includes organic fertilizers such as B. horn shavings or compost.
    • When you open the package, the soil must not smell musty or even rotten.
    • However, an intense earthy smell is normal and desirable.
    • The individual components of the soil should be evenly mixed.
    • Only a few coarse parts should be visible.
    • The fresh potting soil should be fine-crumbly and slightly moist.

    A high-quality potting soil must store moisture well and be able to release it again when necessary. In addition, it must not become hard if it dries up, but must absorb the water quickly when watered again.

    tips

    Most commercially available potting soils are mixed with a long-term fertilizer. However, this does not mean that you no longer need to feed your plants! On the contrary, because the nutrients are used up after about four to six weeks. From this point on, regular fertilization makes sense.

    Store potting soil properly

    Only buy as much potting soil as you currently need. The material is not suitable for long storage, as the nutrients it contains decompose very quickly, especially in warm, humid weather. If there are any bits of earth left over, keep them in the sealed sack and keep them as cool and dry as possible. The dark basement is better suited for this purpose than a sunny balcony. Incidentally, even many garden centers and hardware stores store the potting soil incorrectly: the sacks are stacked on top of each other in the blazing sun and await their buyers. Therefore, if possible, access goods that have been stored in cool indoor areas and away from the sun.

    Change potting soil regularly

    Potted plants should be repotted regularly

    Potting soil is subjected to heavy loads and is therefore used up very quickly. In addition, the natural product accumulates over time with unsightly things such as mold spores and other fungi, bacteria and even pests that lay their eggs directly in the soil. Fungus gnats, for example, are often brought into the house with fresh potting soil. These reasons speak in favor of completely replacing the soil in the pot every one to two years to keep pathogens and pests at bay. Furthermore, your plants benefit from regularly fresh soil, as this is finer and looser than the old one and therefore more aerated.

    digression

    How to dispose of used potting soil?

    It is best to dispose of used potting soil with organic waste or dig it under in a garden bed. The material is great for “hiding” in borders or spreading thinly over the compost and mixing with it.

    Mix the potting soil yourself - instructions and tips

    Up until the 1970s, it was common for plant lovers and nurseries to mix their own soil for flowers and plants. These consisted mostly of compost and peat, loam and clay, sand, charcoal and other substances in different compositions, depending on which plants are to grow in them.

    Good potting soil is a mix of different materials

    Even today, numerous recipes for your own mixtures can be found in gardening books and on the Internet. The basis for this is usually finely crumbly, sandy-loamy garden soil, which our grandmothers took from molehills. This is loose and has just the right consistency for potting soil. Green compost or other humus (e.g. bark compost) as well as bedrock meal and horn meal are added to this. It is also important to observe the correct pH value and, if necessary, to check it with a test strip from the pharmacy. If the pH is too low, add some garden lime (9.70€) (without any other additives!). Now mix the ingredients thoroughly so that the potting soil is as uniform as possible and the individual components are evenly distributed.

    Ideal mixing example for a self-mixed universal soil:

    • one third mature compost
    • two thirds fine garden soil
    • both materials are finely sieved!
    • for loamy garden soil: a handful of quartz sand
    • with sandy garden soil: a handful of clay granules
    • a handful of bark humus (commercially available)
    • two to three grams per liter of horn meal
    • possibly some garden lime

    Most pot and house plants feel very comfortable in this potting soil. So that there are no unpleasant surprises in the form of pests or weeds, you should disinfect the finished soil for a few minutes in the microwave (at 600 to 800 watts) or for half an hour in the oven (at 75 °C).

    frequently asked Questions

    Can I also fill topsoil in the flower pot?

    Topsoil is the top layer of soil, about 20 to 30 centimeters thick. This is essential for plant growth, as it contains many nutrients and is home to active soil life.In principle, you can also use topsoil for your potted plants, but the material also contains admixtures of weed seeds, small stones, root remains and animals. Potting or potting soil, on the other hand, has been cleaned so that you don't have to worry about wild growth in the flower pot.

    The potting soil molds. What should I do now?

    First of all: Not every whitish layer on the surface of the potting soil is mold. In many cases it is just limescale deposits that have accumulated as a result of watering with calcareous tap water. You are harmless. Proper mold, on the other hand, occurs when potting soil with high organic content is poured too much and is therefore too moist. Remove the top, moldy layer of soil, replace it with fresh substrate and water less. Good pot drainage also helps, for example by mixing in sand to increase water drainage.

    Mushrooms are suddenly growing out of my flower pot. Is this bad and what can I do about it?

    If mushrooms suddenly grow in the flower pot, you have probably watered too much. However, the fruiting bodies have nothing to do with the quality of the potting soil, because fungi feed on dead biological material and therefore appear wherever such material can be found. Remove the fruit bodies and water your plants less and the "problem" will go away on its own.

    The potting soil in the freshly opened bag stinks. is she bad

    If fresh potting soil "stinks", i.e. a strong odor emanates from the bag that has just been opened, there is no reason to worry. In particular, soils with organic ingredients such as horn meal or horn shavings, guano, (121.99€) compost, bark humus, etc. often have a very intense scent. Enjoy it (and hold your nose) because the smell is a sign of the good quality of this soil: the microorganisms it contains are doing their job and converting the organic ingredients into nutrients that the plants can easily use. If the scent bothers you, allow the soil in the open sack to air out in a low-traffic area for a day or two before use.

    tips

    If you only want to use the best potting soil for your plants, you should take a look at the test reports from Stiftung Warentest. It was not until July 2022 that they took a closer look at various potting soils and made clear recommendations.

Category:

Vegetable garden