M. Hansen, H. Grønborg, N. Starkey, L. Hansen
For more than 30 years sphagnum peat moss has been the dominating bulk material in substrates for potted plants in Denmark. The quality of peat moss available in Denmark is generally declining and much interest has been devoted to development of more stable alternatives.

It is well known that plants can be grown successfully in many kinds of inert, inorganic and artificial substrates prone to no or very little degradation during cropping. These materials may have drawbacks such as unfavourable appearance, poor handling characteristics or other disadvantages in comparison with sphagnum peat moss. It has been suggested that stability, porosity, ion exchange capacity, water capacity and other important properties can be found in various relatively cheap and readily accessible materials. Accordingly a substrate based on rockwool granules, air dried clay and a lignous carbon source was designed. It has been proven that characteristics very similar to those of peat moss can be achieved.

Several trials have been performed and some of the results from a trial with Pelargonium zonale, 'Red Beauty', will be shown. High quality plants can be grown and nutritional interactions between plants, substrates and feed are very much alike in peat and the alternative substrate. Further trials conducted with Exacum affine, 'Best Blue' have provided additional information.

It is suggested that competetive substrates can be designed and produced without the decomposition capacities inherent in organic materials. Freedom from weeds, pathogens and other contaminants may be beneficial side effects from the use of such substrates.

Hansen, M., Grønborg, H., Starkey, N. and Hansen, L. (1993). ALTERNATIVE SUBSTRATES FOR POTTED PLANTS. Acta Hortic. 342, 191-196
DOI: 10.17660/ActaHortic.1993.342.21

Acta Horticulturae