The tough protective outer sheath of the trunk, branches, and twigs of a tree or woody shrub. Bark is used as the sole constituent in orchid cultivation or as a constituent in potting mixes for tree nurseries and floriculture. Only certain barks are suited as growing media constituents. Bark is also used as a mulching material.

This material is often added in the form of dried granules or as a powder. Clay has a high ability to bind water as well some nutrients. It therefore influences the water characteristics of the growing medium. It can also partly act as a nutrient buffer, making it possible to add more fertilizer without reaching to high salinity levels.

Coir is obtained by mechanical processing of the husk of coconuts. It is primarily imported from the Far East (Sri-Lanka, India, Philippines). This material has good wettability characteristics and is often mixed with other constituents in mixes for sowing, propagating and potting. Sometimes also used as the sole constituent of grow bag mixes in vegetable and flower cultures.

A material produced from organic waste materials such as tree branches, leaves, grass clippings and plant residues. These residual materials are decomposed by microorganisms under controlled conditions. Plants do not grow in 100 % compost, and the material must be diluted with e.g. peat. Good quality composts for the growing media industry are becoming rare in some EU member states due to the increasing use of woody input material for energy production instead of composting.

Peat is formed when plants such as peatmosses are submerged in water and only partly decomposed due to a lack of oxygen. In some areas peat accumulated over the years in small lakes, growing from the bottom to the top. The lower layers of peat are called “black peat”. They are the oldest and most decomposed, characterised by hardly to non-recognizable plant structures and a dark brown to almost black colour. This peat is used in all horticultural segments and is the second most important constituent of growing media throughout Europe.

This peat is weakly to moderately decomposed and taken from the upper and younger layers of a peatland. It has visible plant structure and a yellowish brown to dark brown colour. White peat is used in all horticultural segments and is the main constituent of growing media throughout Europe.

​

​

​

​

​

A material that is manufactured from naturally occurring hydrated volcanic rock (perlite), expanded by heat to form a cellular structure. Usually mixed into growing media in order to improve the flow-ability of a growing media mix, increase the air content and improve the water uptake.

Are the hard protecting coverings of grains of rice and are obtained in the rice manufacturing industry. Rice hulls can be added to mixes to improve air capacity. It is a constituent of lower importance.

​

​

​

Are used in growing media to improve the flowability of the mix as well as to add weight where needed. These materials can also improve the water movement in the growing medium to some extent.

Is made from naturally abundant basalt. It can be adjusted to growers needs and is mainly used in high tech greenhouses. It enables efficient use of resources such as water and nutrients, and is 100% recyclable.

Fibres that have been obtained by mechanically or mechanically-thermally fraying of un-treated wood and/or wood wastes. Wood fibres are used in mixes for pot plants, trees, shrubs, etc. and used in combination with peat and other constituents.