Experienced gardeners rely on homemade growing soil – also called sowing soil – when it comes to sowing seeds or planting cuttings. Not only does it cost less than store-bought – the ingredients can usually already be found in your garden. All you need to make your own potting soil is garden soil, sand and mature compost.
What is special about growing soil?
Growing soil is fine-textured and not loamy like normal garden soil. It is therefore loose and airy and can store water well. Moisture and oxygen are therefore optimally available. Because the growing medium is low in nutrients, seeds and cuttings have to actively seek nutrients and thus develop strong roots. In addition, they do not grow too quickly in the growing medium. This makes them strong and they can later absorb all the nutrients they need in the “normal” potting soil. In addition, potting soil is mostly germ-free so that the young, fine roots do not fall victim to diseases, fungal spores or pests. I’ll tell you how to make your own growing soil here.
What’s in the potting compost I buy?
In the past, you could often buy potting soil and other types of soil that contained peat. Peat has a stable structure and is excellent at storing water. However, the use of peat destroys valuable bogs. It is therefore highly inadvisable to buy such soil. Many manufacturers no longer use peat, which is not necessary. Often you will find perlite in ready-bought growing soil, which at first glance looks like polystyrene balls. In fact, however, they are volcanic rocks that have been popped up. This makes the soil particularly airy, which cuttings especially like.
Making your own growing soil with three components
Roughly defined, homemade potting soil consists of sand, mature compost and garden soil, for example from molehills – in equal parts.
Garden soil: It should be neither too clayey nor too sandy. You should know approximately what the pH value of your soil is. You can find out how to determine the pH value in the Waschbär magazine. It is best to use a deeper layer of garden soil for your self-mixed growing soil. This usually contains only a few weed seeds. The easiest way, however, is to take churned up soil from a molehill. This will give you a wonderful fine crumbly soil that you only need to sift minimally to free it from stones. Sand: It should have a medium grain size. A simple quartz sand will do. You can either get this at a DIY store or simply use some mason's sand. We always used a little sand from our son's sandbox. Coarse-grained sand is also very suitable. Compost: Only use mature compost. It should also have warmed up sufficiently. So you should have put on the so-called hot rotting - at least 30 minutes at over 72 degrees - so that no weed seeds and fungal diseases are contained. The smell of mature compost is pleasantly earthy, the structure is crumbly. Sieve the finished compost through a wire sieve. Coarse sieve residues are returned to the compost heap and serve as a "starter". You can also take wonderful compost from the worm bin for your own growing soil.
Instructions for homemade potting soil
Here you can download the instructions for homemade potting compost as a PDF.
What you need
Sieve Sand Garden soil or molehill soil Compost
And this is how it works
Put soil, sand and compost separately through a medium garden sieve. The ingredients should not be too wet or dry. Remove any coarse pieces that remain in the sieve. Put the sieved components into a container, one third at a time. Mix the ingredients thoroughly.
Make your own growing soil: Tips and experiences
During and after sowing, the soil should be moist, but not too wet. You can sow cress as a test to see if the soil is suitable. If it germinates quickly, grows properly and no other herbs grow next to the cress, you can use the soil for growing without hesitation. If you don't have compost, you can add five to ten percent black soil, so-called Terra Preta. Also add a handful of primary rock flour per ten litres. You often read that the growing soil should be heated to kill germs, fungal spores and pest larvae. However, valuable microorganisms are destroyed in the process. I have had good experiences so far with not sterilising the potting soil in the oven or microwave.
As soon as you have prepared the potting compost, you can start sowing. You can find suitable growing and planting containers for this in the Waschbär shop. Alternatively, the Waschbär magazine has upcycling instructions for making a growing aid out of egg cartons. You will also find tips for sowing from our gardening expert Rudi Beiser in the magazine.
I wish you a good start to the new gardening season!