We studied the composition of the parasitic nematodes in the flowering and ornamental plants cultivated at the greenhouse facilities in the city of Kyiv. We found 9 species from the genera Meloidogyne Goeldi, 1887, Ditylenchus Filipjev, 1936, Pratylenchus Filipjev, 1934, Rotylenchus Filipjev, 1936, Tylenchorhynchus Cobb, 1913, Helicotylenchus Steiner, 1945, Paratylenchus Micoletzky, 1922, and Heterodera Schmidt, 1871. We also discovered the nature of the external manifestations of the nematodes’ effect on the plants and the plants’ response to the infection. Special attention was paid to the loss of the ornamental properties. In order to rank the loss of the ornamental properties of the plants under nematode infection, the scale (ranking system) was suggested. It includes 5 grades applicable to the exterior appearance of the plants, where “5” stands for “excellent”; “4” stands for “good” “3” stands for “satisfactory”; “2” stands for “unsatisfactory”; and “1” stands for “bad”. The joint parasitic activity of two nematode species (D. dipsaci³ and R. robustus in asparagus, and D. dipsaci³ and M. incognita in begonia) caused the highest level of infection progress observed (4 points), and this resulted in worsening of the exterior appearance of plants and in decrease of their ornamentality/ornamental properties down to “bad” (1 point). The parasitic activity of P. penetrans in coleus coincided with a high degree of the infection progress (3 to 3.5 points) while the ornamental properties of the plants corresponded to the gradations identified as “unsatisfactory” (2 points) and “bad” (1 point).