Serbian spruce (Picea omorika (Pančić) Purk.) is an endemic tree species from the Balkan Peninsula. The species also thrives in Slovenia and would be an interesting minority alternative to Norway spruce (Picea abies (L.) Karst.) on some sites. This study was carried out in a Serbian spruce plantation below Počivalnik hill, between Unec and Postojna. The trees were planted in 1988 and are currently classified as a pole stand. We measured the diameters of the trees and systematically evaluated the vitality of each tree throughout the plantation. Data processing consisted of calculating the percentage of trees of each health status for each provenance and phenotype present in the plantation, creating a plantation model, and performing an analysis of variance and Tukey's post-hoc test. We found that provenance has a significant effect on the vitality of trees but not on tree diameter. Phenotype affects both the vitality of trees and tree diameter. The correlation between phenotype and tree diameter is significant within phenotypes B (type 'semidichotomy') and C (type 'serbica'). Also, the impact of phenotype on diameter increment varies between the different provenances. According to our investigations, the most suitable seed material for the Dinaric karst region of Slovenia is from the Šargan provenance (read Shargan). In terms of phenotype, types C (''serbica'') and F ('argentea') seem to be the most suitable. They are also the most desirable for horticultural use.