Supporting garden wildlife through a changing winter

The clearest evidence of the shift is in flowering dates. An analysis of 419,354 first-flowering records for 406 UK species, published in Proceedings of the Royal Society B in 2022, found that the average first-flowering date for 1987–2019 fell a full month earlier than the 1753–1986 average, a trend of 5.4 days per decade correlated with January–April maximum temperatures.

The same study found flowering about six days earlier at southern than northern UK sites and five days earlier in urban than rural settings — one reason city gardens run ahead of published advice. Across Europe, the Woodland Trust's Nature's Calendar records spring advancing at about 2.5 days per decade.

Insects are following the plants. Field studies of buff-tailed bumblebee colonies established in London during the winters of 2005/6 and 2006/7, published in PLOS ONE, found queens and workers foraging right through winter at rates matching or exceeding summer, with mass-flowering shrubs such as Mahonia identified as key food sources. The Bumblebee Conservation Trust has recorded winter-active colonies in southern Britain since the 1990s and runs a recording scheme each November to March.

Laboratory work on the same species found workers able to survive acute cold stress consistent with mild UK winters, including the first demonstration of rapid cold hardening in any hymenopteran — and that pollen consumption measurably affected their cold tolerance. Winter forage is not decorative; it is what makes overwintering survivable.

For gardeners, that translates into three things. Keep something in flower through your coldest months. Keep water available, since dry cold spells matter more than freezing now. And leave seedheads, leaf litter and undisturbed corners standing until late winter, because the insects using them are emerging on a shifted timetable you cannot see.