Adding air to substrates

29.8.2017

Moss and cottongrass provide space for air

Roots need a balanced ratio of air, water and nutrients as well as space to grow. The roots need air, thus the optimal airspace in the substrate is around 40-50%. To add air and improve structural stability of peat substrates Kekkilä combines different ingredients e.g. perlite, crushed cotton grass and Sphagnum moss with premium peat.

Cotton grass is an overflow i.e. waste for many substrate producers. In Kekkilä cotton grass is crushed and utilised e.g. in the production of Kekkilä Grow Board Active Controls. The crushed cotton grass improves drainage and structural stability of the grow boards. More importantly it doesn’t influence liming or fertilising like coir does.

When added to peat, Sphagnum moss improves the structural stability of the substrate. Moss, with its low bulk density,  increases the substrate’s porosity. Moss takes up water quickly and its large cells can store water so that it is still readily available for plant uptake. Like perlite, moss improves re-wettability and speeds up drying. The cation exchange capacity of moss is similar to that of peat. The low pH-level of moss means it may be limed and fertilised like peat.

Moss is light so the transportation costs are low, however, due to it being light it also presses together easily. The peat in the substrate prevents the sinking of the substrate, thus, in the moss added products there is on average 20% of moss. Moss is used in the Kekkilä AirBoost products for hydroponic cultivation of lettuce and herbs. It is being tested for some of the products for forest nurseries which benefit from the improved airiness drainage during heavy rainfall. In Finland Kekkilä successfully tested moss for growing poinsettias. Moss clearly benefits the poinsettia roots which often suffer from the long cultivation period in low light conditions.

Read more about our solutions for growing vegetables, fruit and herbs.