Due to the intensive development of industry and transportation, an increasing number of harmful substances are included in the atmosphere. One of the main elements for improving the atmosphere is the greening of territories, which, along with other functions, also performs a sanitary and hygienic role. The research aims to study the phytoncide activity of woody plants used in landscaping. Phytoncide activity was determined by the chromatographic analysis method. To concentrate phytoorganic substances, an EA–I electroaspirator with a rotameter and a steel tube (10 × 0.2 cm) containing 0.2 g of Polysorb-I sorbent was applied. A gas-liquid chromatograph “Chrom-41” with a flame ionization detector was employed for the analysis. Instead of a column, a capillary measuring 20 × 0.2 cm was used. Samples were taken directly under the canopy of the studied plant. The quantity of volatile substances was calculated based on the area of the peak, determined by generally accepted methods. The analysis of the dynamics of phytoncidal activity in the studied species shows that the peak phytoncidal activity does not coincide with the flowering period in many species. All studied species possess phytoncidal activity, which varies throughout the growing season, reaching a peak from May to July. The results obtained confirm the findings of other researchers that, overall, the dynamics of phytoncidal activity are determined by the intensity of growth processes and photosynthesis.