Organic substrates (Coconut fiber, Peat, ‘Toresa’ Wood fibers), mineral substrates (Rockwool types ‘Grodan’ and ‘Pargro’ and Perlite) and a synthetic substrate (Polyurethane Foam ‘Aggrofoam’) have been used in a recirculating nutrient solution system (Deep-flow-technique) for acclimatization of in vitro plants of Echinodorus aschersonianus Graebner, a tropical aquarium plant. Plant survival and growth were influenced by the substrate used. For evaluation of plant growth leaf number, length of the largest leaf, root length, leaf and root dry weight were determined. Plant development was similar on the commonly used Rockwool (‘Pargro’ and ‘Grodan’), Peat, ‘Toresa’ Wood fibers and Aggrofoam. On Coconut fibers, the plants were significantly taller and more vigorous. On Perlite, the plant growth was clearly inhibited.