The features of dynamics of height of vegetative organs of different types of decorative plants are studied at the joint sprouting in parks associations. Three types of influence of the fitogen field are educed on ростов of vegetative organs of the studied plants: oppressive, neutral and stimulant. Drawn conclusion, that suppression of ростовых processes of vegetative structures in the area of action of the fitogen field of nearby plant is determined by competition relations in a fight for the use of resources of environment. Opposite situation the − increase of height of vegetative organs can be related to positive influence of volatiles, distinguished by plants, which shows up through biochemical stimulation, and also as a factor of sanitary of air space round plants