Two experiments were conducted, in which the granulated rockwool 'Grodan', utilised rockwool 'Flomiin' used before as slabs and remained after 2-year carnation culture (UR) - shredded and steamed and two kinds of insulation rockwool of domestic production: from Gliwice (RG) and from Nidzica (RN) were used as a substrate or its ingredient for mentioned in title plants. Particular plant species expressed somewhat diversified reaction, but generally rockwool showed full usability as a substrate or its component. The best kind appeared to be UR. RG was good in the mix, where it was in 25% of the volume, but RN was unsuitable.