The Biblioteka Uniwersytetu Warszawskiego (BUW) or the Warsaw University Library building was opened in December of 1999 and the Library garden in June, 2002. One of the largest and most beautiful roof gardens in Europe, the Biblioteka Uniwersytetu Warszawskiego (BUW) or the Warsaw University Library encompasses two garden areas – an upper area of 2,000 m2, and a lower area of 15,000 m2 – linked by a fountain of cascading water. The roof garden setting offers sweeping views of Warsaw, the Vistula river and the Świętokrzyski Bridge.

The roof garden of the Library of the University of Warsaw is an experimental project. It is the first and largest roof garden established in Poland of its kind. It offers exceptional views to the Vistula River, fragments of the natural declivity, and the buildings situated downhill. The variety of the scenes created and beauty of the panorama remain the greatest values of this place.

The design concept falls into the formation of several separate, yet conjoined gardens. The functional and spacial divisions, outlined by the skylights, technical equipment and entrances to the roof (platform, off-ramp), were inspired by the idea of creating varied garden spaces differing with spirit, colors, forms and scents. The Warsaw University Library has various slopes for each section of the roof; there are flat parts sloped 0-2% and also pitched areas up to 100%.

The roof garden was established strictly with the use of ZinCo technology solutions, yet to increase cost savings the investor decided to use a growing medium made of locally available ingredients (composed of fertile soil and crushed brick). Initial testing proved suitability of the fertile soil from Umiastów, however the use of the recycled brick resulted in altering of the pH into alkaline (over 7,0). Regular testing still confirms the excessive alkalinity.

The drainage element Floradrain® FD 40 was used for the intensive green flat roof and Floraset® FS 75 was employed in the pitched area. The height of the substrate layer varies from 200 mm to 400 mm depending on the type of vegetation (lawn, perennials or shrubs).

The roof garden was planted in spring 2002 which came very early and turned outstandingly warm and mild. Yet, the weeds started to grow rapidly (Galinsoga and wormseed) and maple seedlings soon appeared. Successive years proved inadaptation of certain selected shrub species to the conditions on the roof – bare and exposed to both the sun and cold eastern winds. For example, the silverweeds did not recover, nor did Festuca glauca, due to the excessive moisture of the substrate. Yet on the contrary, the roses felt extremely comfortable growing far too high. The success in roof greening lies with the planners who work on the design concept, make the choice of the relevant technologies and plant species and finally take care of the proper installation. Yet, it is worth reminding that at the same time this success lies with the gardeners who are in charge of maintenance of the roof garden.

The Warsaw University Library roof garden is flourishing with a very large plant list – plant-lovers will find much to admire. See the entire list at their case study below.