There are many chemical compounds in the plant-growing practice, used for regulation of the growth, development, productivity and sustainability of plants. The efficiency of the exogenous application of the synthetic compounds depends on the type and physiological age of the plants, as well as on the concentration and time of application of the relevant regulator. The synthetic growth regulators are usually divided into two groups. The first group includes compounds with structure and function similar to those of the natural growth regulators. These are for example the synthetic auxins, gibberellins, cytokinins (synthetic stimulators) and the ethylene-releasing substances (synthetic inhibitors). The second group comprises compounds without close analogues in plants but cause effects similar to the natural regulators. Apart from growth regulators, there are several other compounds used in the agricultural practice – herbicides, fungicides, insecticides, defoliants, desiccants, etc. They are not growth regulators but in many cases the difference between them and the growth regulators is hardly perceptible. Depending on the dose, a compound may be a growth regulator or a herbicide, fungicide, defoliant, and so on.