The outdoor grounds of the botanical garden spans around 8 hectares. A wheelchair-accessible circular trail, approximately 1 kilometre long, guides visitors through the garden. Large parts of the garden are designed to match the domed greenhouse with its triangular windows and trapezoid entrance area: the routes and plant plots were laid out on the basis of its striking angles, for example.
As you follow the circular trail, you first encounter the demonstration section, which contains a wide variety of plots, not all of which are exclusively used for educational and training purposes. The agricultural and medicinal gardens, a large section dedicated to useful plants and shrub beds, collections of endangered plants and a plant breeding area present fascinating and illustrative information about the plants from a botanical and a gardening perspective.
The trail continues to the geographical area, whose spaces are designed authentically to resemble specific natural environments. Its first section is dedicated to perennials and woody plants from North America. Impressive bald cypresses line the upper part of the little creek that runs through this landscape. Coast redwoods, giant sequoia and rare Rocky Mountain bristlecone pines represent evergreen coniferous forests; eastern black walnut trees, magnolias and oaks are typical of the region's deciduous woodlands.
At the end of the creek, the Chinese section begins with a bamboo grove, Chinese fir trees, slender gingko trees and ornamental flowering shrubs, such as weigela, viburnum and magnolia. In spring, white skunk cabbage (Lysichiton camtschatcensis) and primroses fill this section with blossoms.
The neighbouring Japanese section is also characterised by plentiful bamboo groves. Japanese cedars, nutmeg yews and plum pines make up the Japanese coniferous forests of this section, while star anise, bay trees and sclerophyllous oaks represent the country's evergreen broadleaved forests. In spring, flowering cherry trees are in bloom; in autumn, colourful maple leaves light up the landscape. Many of the perennials we use in our own gardens originally came from Japan: hostas with their splendid leaves, primroses, anemones, daylilies, and various irises.
The next section is dedicated to the Caucasus. Nordmann firs, Caucasian spruces, Oriental beeches, zelkova trees and Caucasian oaks dominate this area. Its undergrowth is home to various paeonies, Lenten roses and dwarf Russian almond shrubs.
The last part of the geographical area represents Central Europe. In the oak and hornbeam forest, a dense canopy of oaks, ash trees and other large deciduous trees provides shade to an undergrowth of hornbeams, holly and yews. Anemones, periwinkle and wild garlic flower here in spring.
The path continues towards the fruit orchard and a section with plant communities representing natural habitats. A community of pines showcases heath, grasses and pasqueflowers. In a little marsh, the botanical garden keeps a large number of endangered plant species from a conservation area. The Alpine section in the north of the garden is currently undergoing an extensive redesign project. It will soon reopen to the public with a new pond system, an Alpine meadow and a rockery.
Embedded in a large, grassy field lies the systematic section. Its flowering plants are arranged by classification based on Rolf Dahlgren's system of taxonomy. It shows the family tree from a bird's-eye perspective; the individual branches are represented by organically shaped flowerbeds containing closely related plants.