Evaluation of pollinator friendliness of an ornamental aromatic planting concept

Small green spaces in urban areas can contribute improving the food supply for insect pollinators, however, there is a lack of knowledge in the field of pollinator friendly ornamentals.
In order to adress this lack, we conducted a study covering the plantation and evaluation of an aromatic bed using 16 plants typically used in horticulture.
The plants were chosen to have the appearance of wild perennials, covering a long flowering period and being considered pollinator friendly.
This included representatives of Lamiaceae (6), Apiaceae (2), Asteraceae (2), Caprifoliaceae (2), Brassicaceae (1), Caryophyllaceae (1), Crassulaceae (1) and Verbenaceae (1). At the experimental area of LVG Heidelberg, Germany, sections of this demonstration planting were used for pollinator counts.
These countings were performed between May and September 2019. The aim of this study was twofold: firstly, to evaluate which plants especially attract pollinators and secondly, to observe what kinds of pollinators visit the flowers.
According to our results, the three top performers were Foeniculum vulgare, Lavandula angustifolia and Satureja montana, attracting on average between 8.0 and 9.1 pollinators within 10 min, thus making up 60.6% of all pollinators.
All other plants were on average visited between 2.2 (Sedum telephium) at most and 0.3 (Verbena bonariensis) at least per 10 min.
The composition and diversity of pollinators varied a lot.
While Lavandula and Satureja were mainly visited by honey bees (60 and 68.6%), being followed by wild bees (20 and 13.1%), Foeniculum was mainly visited by other pollinators (63%, mainly wasps and flies), being followed by wild bees (18.9%), hoverflies (15.7) and honey bees, the latter accounting for only 2.4% of Foeniculum pollinators.
These findings seem to suggest that regarding the combination of plants few highly attractive plants concentrate the pollinators’ attention, leaving the rest of the plants mainly disregarded and seldom visited.

IV International Symposium on Horticulture in Europe – SHE2021

V. Joedecke, H. Stier, U. Ruttensperger

urban species conservation, biodiversity, ornamental plants, perennials, horticulture, garden flowers

https://doi.org/10.17660/ActaHortic.2021.1327.44