One attraction in the outdoor area is the 0.5 hectare alpine garden which has no equal in northern Germany. You can discover quite particular and colorful adaptations in plants that the complex of extreme environmental factors on limestone-based or silicate-based soils has provoked during the evolution of plants at high montane and sub-alpine altitudes. On the other hand, many adaptations have evolved in an interestingly similar way (convergent evolution) in very different groups of the plant system. Thus, many plants are often dwarf, cushion-shaped, with runners or bulbs, the leaves green for a long time, the flowers comparatively large, numerous and simultaneously in bloom, and the seeds are often wind dispersed.
Plants from all of the major mountain regions worldwide are represented here: some that grow in limestone-based soil, and others that grow in silicate-based soil. Since above the tree line the soils are quite undeveloped and shallow, the chemical effects of the rocky substrate have a direct impact on the plants that grow there. Crystalline and silicate materials like granite, bunter, and gneiss create much more acidic soils than limestone, marl, or dolomite, which produce soils of a nearly neutral pH (± 7).
In this area, the plants are cultivated accordingly in the silicate rock or limestone section, and then arranged according to their geographical range.