On a few fields in Grengiols there is a wild tulip species, which does not grow anywhere else. Every year during the second half of May the village attracts many visitors who come to admire this special tulip.
The origin of the Grengiols tulip (Tulipa grengiolensis) has not been cleared up entirely. Its closest relatives can be found in Turkey. The tulips used to grow on many fields around Grengiols. Due to rationalisations in agriculture they then seemed to disappear completely. Thanks to a Pro Natura initiative and the tulip guild, the Grengiols tulip could be protected, though. Today the fields are specifically cultivated so that the tulip can be preserved.
Since autumn 2009 visitors can enjoy the new circular trail at the tulip hill. The “tulip orbit” does not only lead to the tulip fields but also to the other natural and cultural projects. The path leads for instance to one of the most species-rich dry meadows in Switzerland and for a short passage it also follows the old water conduit “Afteri.” Furthermore, there is a new biotope near Milibach, which is a beautiful pond that invites to play in summer.