In response to environmental concerns and the need for peatland conservation, alternative growing substrates for ericaceous plants production must be investigated. The objective of this study was to evaluate the use of coir as component in rooting substrates for Calluna vulgaris and deciduous and evergreen cultivars of Rhododendron. Six rooting substrates containing different amount of coir, sphagnum peat moss, perlite and sand (% by volume) i.e. 0-70-10-20 (control), 15-75-10-0, 20-55-10-15, 25-65-10-0, 30-65-5-0, 35-65-0-0 were tested. Apical cuttings were collected between mid-June and the end of July and were evaluated next spring after overwintering. There were no differences in the pH of tested substrates used in this experiment (pH 5.7 - 6.1). Increasing amount of coir in the substrates resulted in increased electrical conductivity, with the highest EC of 35-65 coir to peat (0.31 mS cm^-1) compared to 70-10-20 peat to perlite to sand (0.06 mS cm^-1). The best rooting substrates for Calluna vulgaris ‘Dark Beauty’ were those containing at least 15% of coir. The highest rooting percentage and root rating for Rhododendron ‘Geisha Orange’, ‘Sunte Nectarine’ and ‘Roseum Elegans’ was obtained in the substrate 20-55-10-15 coir to peat to perlite to sand. This substrate showed high total porosity (85%) as well as high water content (62%) and air content (24%), measured at standard pressure head –10 cm H₂O. Increasing amounts of coir in the substrates above 20% resulted in decreased rooting percentages as well as root ratings, especially for Rhododendron ‘Roseum Elegans’. Superior root quality and quantity of cuttings rooted in substrates amended with coir, resulted in enhanced bud-break and growth flushes of Calluna vulgaris ‘Dark Beauty’, Rhododendron ‘Geisha Orange’ and ‘Sunte Nectarine’ cuttings.