A SLOW-RELEASE FERTILIZER FOR NURSERY PLANTS IN CONTAINER

During three years at three locations, experiments with a shrub (Pyracantha) and a conifer (Chamaecyparis or Cupressocyparis), grown in containers, were carried out to establish whether the slow-release fertilizer Osmocote 18+6+12 with a release period of 8–9 months, mixed through the potting soil as a basal dressing at the start of the season, could replace topdressings of the water-soluble NPK-compound 18+6+18 Kristallijn, given weekly during the growing season.

Between the two methods of fertilization only small, variable differences in growth occurred so that these methods may be considered equivalent.
A strongly growing plant may derive some extra benefit from a combination of a suboptimum rate of Osmocote with continuous or late topdressing of Kristallijn.

High rates of each fertilizer may be detrimental to the quality of Chamaecyparis by producing a poorly shaped plant, and diminish winterhardiness of Pyracantha.

Symposium on Substrates in Horticulture other than Soils In Situ

J. van der Boon

https://doi.org/10.17660/ActaHortic.1982.126.39