What happens to plants in the winter?

Dr Trevor Dines

Dr Trevor Dines

Plantlife Botanical Specialist

1st February 2018

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Dwarf mouse-ear (Cerastium pumilum)

In the dead of winter when all’s grey and monochrome, it might seem that the world of wildflowers is dormant. But far from it. In fact, the sap never stops flowing and all sorts of hidden processes are going on...

For instance, the seeds of yellow rattle (Rhinanthus minor), an annual of wildflower meadows, need winter temperatures of 0-5C for at least three months in order to germinate. This stratification – a sort of cold clock - breaks seed dormancy in spring, triggering germination of seeds in March when other plants are just beginning to grow. As the seedlings develop, their roots tap into those of grasses growing nearby, reducing their growth by up to 60% and creating space for other flowers to grow. Because of their inherent cold dormancy, yellow rattle seeds should always be sown by November at the very latest.

Some small plants escape the harsh, dry conditions of summer by growing through the winter instead. These ‘winter annuals’ begin life by germinating in autumn, growing stems and leaves through winter and then flowering in very early spring. Their seeds ripen and are shed in late spring, the plants dying in time before temperatures rise and soils become dry. Plants like dwarf mouse-ear (above - Cerastium pumilum), rue-leaved saxifrage (Saxifraga tridactylites), spotted medick (Medicago arabica) and dune fescue (Vulpia fasciculata) grow on very thin, shallow soils in coastal areas that are prone to drought and where mild temperatures mean they can grow through the winter. These plants can be absolutely tiny – dwarf mouse-ear often flowers when it’s less than a centimetre tall and has just three pairs of tiny leaves.

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Going on a wintry walk?

Why not take along Plantlife's winter wildflower spotter sheet and see what common species from catkins to snowdrops you can spot out and about?

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