Influence of fertilization application and growing substrate on container-grown woody ornamentals

Five fertilization systems and seven types of growing substrates were tested with two woody plant species with different nutritional demands (Thuja occidentalis, Pyracantha coccinea) grown in two-litre containers. The experiment was repeated in two vegetative seasons. Application of controlled release fertilizer (CRF) was proved the most reliable; it gave good or at least average results in dependence on used growing substrates. Significant differences between application of CRF and other fertilization systems were with Pyracantha plants. System using slow release fertilizer with additional nitrogen fertilizing also showed good results. Systems based only on liquid feeding were less reliable, with some substrates they showed very good results; with others (peat substrate, peat bark substrates with wood components) they were bad. Similar results were achieved with top dressing of granulated fertilizer. Evaluating the substrates good results were obtained by using mixtures of peat with components with higher content of nutrients - peat bark substrates, peat bark substrates with compost and non-peat mixtures of composted bark, wood fibres and compost. Significant differences between these types of substrates and peat one or peat bark substrate with wood components were both with Thuja plants and especially with Pyracantha plants, which have higher demand for nutrients. The experiments showed that peat based substrates amended with alternative components or non-peat substrates can bring better results than the peat ones.