This paper presents results of previous research. which may prove useful for the re-introduction of hypericum to crop fanning. Climatic conditions for growing this herb in Poland are quite good. It requires fertile soil, with light or medium firmness (compactness), which is permeable and sufficiently wet, and has a slight acidic reaction. The forecrop is very important in this case. Hence, this paper evaluates its effect on the healthiness of plants and thus time-scale tor plantation usage. The studied plantations were established after potatoes and wheat. It was observed that hypericum grew very slowly in the first year and was labour consuming due to weed control. A two-year old plantation gave dense herb growth independently of the forecrop. However, in the spring of the third year, hypericum sprouted irregularly. Herb plants in the after-wheat plantations showed retarded development in 39% and up to 34% of the plants in the after-potato plantation. Moreover, single stalks, decreased height or poor foliage was also observed. Laboratory diagnostic tests showed that stalk bases, root necks and main roots were intensively infested by the fungi that arc pathogenic for most crops, i.e. the species of Botrytis, Fusarium. Phoma and Rhizoctonia.