Posts Environment, Forestry

Sphagnum moss would have a lot to give to greenhouses in Finland and elsewhere in Europe, but penetrating growing medium markets dominated by peat may take some time.

Growing media used in greenhouses are worth billions: their market value in Europe is over EUR 2.5 billion and in Finland alone EUR 9 million.

Peat is by far the most popular growing medium, taking up almost 90% of the market. In Finland, about a million cubic metres of peat is extracted a year to be used as a growing medium.

Although peat has many good qualities, its use is no longer expected to increase – quite the opposite in fact. Wetland protection is on the rise in Europe, meaning that the use of peat is decreasing. Britain, for example, is planning to stop using peat altogether as a growing medium by 2030.

Alternatives to peat as a growing medium include synthetic mineral wool, perlite and coconut fibre. However, these will probably not be accepted by the Britain who claim they want to replace peat with an even more ecological alternative.

Finnish Sphagnum moss could well be an answer.

Kuva: Erkki Oksanen / Luken arkisto
Photo: Erkki Oksanen / Luke’s archive

Promising growth results

Senior Research Scientist Juha Näkkilä of Natural Resources Institute Finland has been finding out how greenhouse vegetables grow on Sphagnum moss growing media. The results have been promising.

“Greenhouse vegetable seedlings grew just as well with ebb and flow irrigation on the Sphagnum moss growing medium as on peat ,” says Dr Näkkilä.

Sphagnum moss is actually even better in closed irrigation systems, because there is no release of humus, which is an impediment to certain disinfection methods. Moss also seems to have some properties that inhibit mould fungus growth, and brown mould, which is common with peat, will not grow on it.

Näkkilä’s colleague, Senior Research Scientist Juha Heiskanen from Suonenjoki in central Finland studied whether Sphagnum moss is suited as a growing medium for spruce seedlings. He discovered that the seeds germinated and the seedlings grow almost as well as on peat.

According to Dr Heiskanen, the difference can be explained by the particle size and basic fertilizer in the Sphagnum moss growing medium not being optimal in the preliminary test.

“It’s a matter of fine adjustments. Once you find the right balance, I have no doubt about Sphagnum peat moss being just as good as peat.”

Is there a market?

Finland has 300,000 hectares of areas suitable for harvesting Sphagnum biomass.

“When Sphagnum moss is harvested, the top layer of 30 centrimetres is removed. The vegetation is estimated to grow back in about 30 years. This means that 20,000 to 30,000 hectares would be enough to harvest all the Sphagnum moss that is needed”, says Docent Niko Silvan, a Luke researcher.

So far Sphagnum moss is not harvested on a commercial scale, because it is too expensive.

The future of Sphagnum moss probably depends on how much peat harvesting will be restricted in the future and whether Britain really will stop using it.

“The technical problems concerning the harvesting can be overcome. Now all we need is genuine demand and economies of scale,” says Dr Silvan.

Dr Näkkilä agrees.

“Sphagnum moss is a good, domestic and sustainable growing medium that deserves a place in the market.”

Text: Maria Latokartano