Olives from Lun are a unique botanical park of different olive genotypes. On an area of approximately 400 ha, there are several thousand olive trees of unequal age and different genetic and morphological characteristics. Successful flowering and fertilization is a precondition for a quality olive crop. Emphasized climate change in the last few years significantly affects the time of occurrence and duration of the flowering phenophase. Of the climate elements, flowering can be influenced by: temperature extremes, sums of active and inactive temperatures, wind, air and soil humidity. Therefore, it is important to monitor the timing and duration of the flowering phenophase every year. The topic of this paper is to monitor the occurrence, duration and end of flowering in 10 olive phenotypes in the olive grove complex of Lun in 2020. Selected trees are located at different microlocations of the named complex. The paper concluded that there is a significant difference in flowering time between some olive genotypes in Lun. In olive genotypes 2, 3, 4, 6 and 9 there is no difference in the beginning and duration of the subphenophases of the flowering phenophase. In the case of genotype 1, the phenophase of flowering started at the earliest, and in the case of genotypes olive 5 and 10, the phenophase of flowering started at the latest. The olive genotype 8 was 4 days late opposed the olive genotypes 2, 3, 4, 6 and 9. The olive genotype 7 was 7 days late opposed the olive genotypes 2, 3, 4, 6 and 9. The beginning of flowering was recorded on 19 May at the earliest, and June 1st at the latest.