GROWTH REGULATION OF CONTAINER GROWN PLANTS
The growth regulation which was performed in older time was always one-sided, with the aim of dwarfing the plants. The primary way of restricting the growth was pruning. Not pruning the top alone, but especially by pruning the root. It is not expressed clearly in literature, but one gathers the impression that the essential feature in the elaborate technique which often is described in many books for dwarfing plants, is root pruning. This view is corroborated by several modern experiments, which show that transplanting of trees, and in the same time damaging the root system always restricts the growth of the top of the plant for a certain time. Of course other horticultural techniques may help in slowing down the growth of the top, such as starving the plants for nutrients or water; but this can not be done without influencing the normal healthy look of the plants. Other ways of dwarfing plants have been found in the course of time, such as grafting strong growing specimens on weakgrowing rootstocks, or just by growing natural dwarfing variants of different species, variants which have arisen either as seed-plants or as mutation on normal plants.
Recently the possibility of using growth substances as a tool for regulating the growth pattern of plants has been added to the more wellknown practices which are mentioned above.