Many traditional bedding plants have been bred for appearance, often to the detriment of flower structure and function. Consequently, these colourful plants are often of little value to our declining pollinators and wider biodiversity.
In 2017 we conducted a series of plant trials to determine the suitability of various plants as bumblebee-friendly bedding, and to explore whether foliar feeds could boost the production of nectar and pollen.
Mignon Series dahlias: discovering bumblebee preferences.
Dahlias with simple, open flowers make excellent bedding plants. In 2017, citizen scientists from across the UK grew and surveyed red, white and purple Mignon Series dahlias. We received 854 surveys, and found that the flowers were visited by ten bumblebee species, predominantly Buff-tailed Bumblebees, White-tailed Bumblebees and Common Carder Bees. Bumblebees did not show a significant preference for a particular colour form.
The bright colours, dwarfing habit and long flowering period of Mignon Series dahlias makes them suitable bumblebee-friendly bedding plants. Unlike many plant species used in traditional bedding displays such as pelargoniums and begonias, single flowered dahlias are a good source of nectar and pollen for insects.
Chaenostoma (Bacopa): a new RHS Perfect for Pollinators plant?
Chaenostoma (often listed as Bacopa and formerly Sutera) is a popular trailing plant. In 2017, we grew and surveyed white, pink and blue colour forms from the Abunda Colossal Series, to determine whether they were worthy of being added to the RHS Perfect for Pollinator list.
Although Chaenostoma was visited by bumblebees less frequently than many of the other surveyed flowers, we did also observe foraging solitary bees, hoverflies and butterflies, suggesting it may support a range of insects and be a better option than traditional bedding plants such as Pelargonium. In order to gain more conclusive evidence about the merits of Chaenostoma, further research is required.
Bird’s foot trefoil: a bumblebee-friendly container plant?
Bird’s foot trefoil (Lotus corniculatus) is a UK native, with bright yellow and orange flowers. It is an important source of nectar and pollen for insects. In 2017, we conducted a trial to determine its suitability as a hanging basket and tub plant. Although the Bird’s foot trefoil was visited by bumblebees less frequently than many of the other surveyed flowers, it was regarded as attractive container plant by gardeners.
Nasturtium: do cultivated varieties vary in their value for bumblebees?
Nasturtium (Tropaeolum majus) is a bright, easy to grow annual that provides bumblebees with nectar and pollen. In summer 2016, we carried out a small field trial to compare seven cultivated varieties of nasturtium, to determine whether they produced different amounts of nectar and pollen, and which were the most visited by bumblebees. We are currently analysing the data.
Foliar feeds: can they improve nectar and pollen provision for bees?
Tubs, hanging baskets and window boxes are great ways to introduce additional flowers into gardens. However, growing media contains a limited amount of nutrients, and deficiency can result in stunted growth and poor flowering. In 2017, we conducted a trial to determine whether foliar feeds could increase the production of flowers, nectar and pollen.
Foliar feeds had no significant effect on the number of flowers produced, or the amount of time bumblebees spent foraging. Although flowers from plants receiving a comfrey feed produced nectar with more sugar and greater pollen volume, there was no statistically significant effect.
Despite the lack of significant results, foliar feeds are a great way to apply micro and macro-nutrients to give plants a quick pick-me-up. It would be worth conducting further experiments using a wide range of popular garden plants which may absorb feeds differently.