Compost for germination in seedbeds

In the world of compost, although it may seem that everything is very similar, there are different ways of making, compositions, raw materials that provide subtle modifications to the final product. These modifications are important according to what times and one of them is in the delicate planting. It is also suitable for growing in pots.



We have already spoken in Gardenprue a lot about compost and we are not going to extend too much. A quick and brief way to define it is “organic matter decomposed to a greater or lesser extent.” As we all know, there are nuances that must be specified about what type of organic matter, or the degree of decomposition of it. These two aspects (raw material and decomposition time) are what will define the type of compost and therefore its subsequent application. It does not occur to anyone to add fresh manure to a seedbed, but to a bottom fertilizer months before planting the crop. It is organic matter in both cases, but the degree of decomposition greatly affects the physiological phase of the plant. Here is some more information about composting.

+ Compost quality checks

+ Operating principles of the composter

+ Composters. Types and forms of use

+ Infographic on how to compost

And if you’re still not happy with these articles, check out our full archive on composting .


When we compost, we witness a more or less long decomposition process in which the raw material that we add is gradually transformed. The conditions (more or less optimal) define the time of the complete process (from fresh organic matter to what we call very mature compost or mulch). Let’s think about what a seed and a plant need in their early stages of development.

It is a delicate moment. Many times it needs specific environmental conditions and substrate and their control to provide good germination, so the substrate must accompany this process. General characteristics of the sowing compost:

  • We can’t just use compost. This must be mixed with substrates in different proportions .
  • It must be very old. More than a year old,  whose organic matter is in the process of mineralization.
  • It has to be balanced . Normally, very mature compost is balanced ( C / N ratio )


If we only use this type of compost or in a very high proportion for sowing, we will suffer from excessive compaction , drowning the roots and not leaving enough oxygen or drainage. This causes root suffocation and the plant can germinate but will soon rot. We must mix it with vegetable fibers that lighten and increase the volume of the substrate, achieving better drainage and aeration.

Suitable average proportions:

  • 40 ± 10% very mature compost (more than one year)
  • 30 ± 10% of  dry leaves composted . You can start doing this now! (fall). It gives it the fibrous part that will provide the aforementioned drainage and aeration. You can use coconut fiber as well.
  • 20 ± 10% mature compost (it does not have to be as old as the previous one).
  • 10% vermiculite. This lightweight material has a lot of water retention capacity and maintains a very constant humidity level.

The percentages are approximate and never fixed. As you can see, they can vary around 10% or a little more per item without noticeable differences. They are indicative percentages .

Finished mulch

Do you have something to sow? Well, you already know how to do it successfully!

Leave a Reply

Your email address will not be published. Required fields are marked *