Abstract: The growth medium consists of a homogeneous mixture of short rockwool fibres, and short vegetable fibres, preferably peat fibres. Humus material may be added, preferably composted sludge. To the mixture may also be added fertilizer, and seeds, e.g. grass seeds being bound to said fibres by a rapidly disintegrating binder.The method for producing said growth medium comprises intimately mixing long rockwool fibres, and vegetable fibres, preferably peat fibres, and possible additional materials in a dry state in a mixer until homogenous spheres or balls are formed which contain the components in a substantially uniform mixture, and cutting said spheres into short fibres by the aid of beating knives, a hammer mill or the like, and then conveying said medium to the growing site or to a packaging by the aid of an air jet.