Bumblebees are predominantly active from early spring until autumn. Use your garden and allotment to provide a continuous supply of flowers throughout the year, especially early and late in the season, when there is often less forage available for insects.
Provide blooms throughout the year
Bumblebee queens start to emerge from hibernation in around mid-March. They will have been fertilised in the previous year and need to feed themselves and provision their nests before they can lay their first brood of eggs. Flowers such as lungworts (Pulmonaria species), crocus (Crocus species), dandelions (Taraxacum vulgare) and dead-nettles (Lamium species) are important at this time.
Although we think of summer as a time of floral abundance, there is often an early summer gap, when spring flowers have faded and many summer blooms have yet to get going. Good plants to bridge this gap include foxgloves (Digitalis species), most roses (Rosa species), hardy geraniums (Geranium species), red valerian (Centranthus ruber), and honeysuckle (Lonicera pericyclamenum).
Some bumblebee colonies will remain active into late summer and autumn, especially those species which fit two life cycles into one year. At this time, new queens also need to build their energy ready for hibernation. Plants that provide late sources of flowers include dahlias (Dahlia species), stonecrops (Sedum and Hylotelephium species) and asters (Aster and Symphyotrichum species). In 2015, the RHS Plants for Bugs study concluded that many exotic, southern hemisphere species such as flowering tobacco (Nicotiana alata) and nasturtiums (Tropaeolum majus) were great for extending the flowering season.
Although queen bumblebees hibernate during the winter months, some species are increasingly observed to have active colonies in milder regions and urban areas during winter. As a result, winter flowering garden plants such as mahonia (Mahonia species) and heather (Erica carnea) can be valuable food sources.