The City of Offenbach and Stadtwerke Offenbach have set themselves the goal of cultivating plants in suitable substrates so that they are easy to care for and thrive on Offenbach's streets. In order to determine whether the project works as planned, an extensive test is to be carried out in close cooperation between the Office for Urban Planning, Traffic and Construction Management and the greenery department of the municipal utilities company.
On Mühlheimer Strasse, between the Untere Grenzstrasse junction and the Bischofsheimer Weg junction, three different substrates will be tested with and without different mulching materials. The site conditions are comparable in all planting areas: It is often sunny, dry and hot there in summer. When selecting the planting substrates and mulch materials, care was taken to ensure that transportation distances were not too long and that smaller quantities were available. For ecological reasons, the substrates must be free of peat.
Head of Construction Paul-Gerhard Weiß explains the project: "There are numerous manufacturers on the market with different substrates for perennial plants. With the right substrates, the amount of care required can be reduced considerably, which saves a lot of time. After the heavy pruning in spring, maintenance by our experts from ESO Stadtservice is now limited to the targeted removal of unwanted growth. It is important to me that we also test perennials that can withstand the dry and hot extreme locations and at the same time provide a habitat for insects."
"The gardeners at Stadtwerke have already created perennial beds along the main traffic arteries of Berliner Straße, Taunusring and Odenwaldring in coordination with the city planning department, where they are recording the suitability of perennials for the respective location," says treasurer and department head Martin Wilhelm. "Stadtservice is creating these attractive areas with the money from the special budget that the city council has made available to it since 2019 for additional watering in dry and hot summers, for planting new trees and for creating new green spaces with flowering plants," says Martin Wilhelm. "The positive response from citizens shows that this money is well invested and that the areas resulting from the cooperation between the city and Stadtwerke Offenbach are a benefit for Offenbach."
Splendor of flowers and food for insects
The areas along Mühlheimer Strasse will be planted with a uniform mixed planting of perennials and grasses that tolerate drought well. This mixed planting has been chosen so that it is varied all year round and provides insects with food throughout. Flowering perennials are supplemented with early-flowering bulbs, ensuring a beautiful display of flowers from February to October/November. Sturdy inflorescences and evergreen ground cover plants take center stage in winter, making the planting attractive even in the cold season and offering overwintering opportunities for insects.
"Our aim is to keep in constant contact with Stadtservice to record and evaluate the experience of the care team's experts and transfer it to other areas at a later date. In the long term, we can reduce costs and at the same time maintain an attractive and long-lasting appearance of the planting. The implementation was carried out by the Stadtservice team in cooperation with the Office for Urban Planning, Transport and Construction Management. Now the maintenance phase begins with monitoring to observe the development on the various substrates," Weiß concludes.
Background:
Almost 1300 square meters of area will be provided with sustainable and drought-tolerant planting. 12,000 perennials and grasses as well as around 30,000 flower bulbs will be planted. Around 400 cubic meters of substrate will be installed in three variants and the planting areas will be covered with almost 100 tons of mulch. A tree pit substrate, a planting substrate such as that used for green roofs and a purely mineral substrate are being tested to assess these extensively maintained perennial areas.
To protect the perennial planting, a five-centimetre-high mineral mulch layer of gravel or chippings is applied and, for comparison, no mulch cover is used. The mulch layers are intended to reduce wild growth, minimize compaction of the planting substrate and protect the surface from evaporation.
Organic mulch materials such as bark mulch are not suitable for the perennials selected there. When using the mulch cover, it is particularly important to determine whether a different amount of work is required to maintain the areas, whether the layer becomes compacted and whether evaporation protection is evident. This may reduce the need for additional irrigation.