In ‘The Flowers that Bloom in the Spring’ from The Mikado, Gilbert and Sullivan were interpreting the seasons according to their 19^th Century climate – but do these flowers still, indeed, bloom in spring? The Meteorological Office’s traditional definitions of the seasons in the UK are:

• Summer from June to August
• Autumn from September to November
• Winter from December to February
• Spring from March to May

Increasingly, climate change is blurring these distinctions, and gardeners are seeing autumn stretching well towards January. Winters in maritime Great Britain are now most severe in February and March, and summer extends into September. The effects of prolonged warm autumns include accelerated growth emergence and flowering of plants which have been thought of as the harbingers of spring.

Phenological studies in the late 20^th and early 21^st Centuries established that the then-termed ‘early-spring flowering plants’ had accelerated blossoming by as much as four weeks. Now, in the second decade of the 21^st Century, it seems this is an underestimate.

Pictured above: Iris unguicularis (styllosa); the Algerian iris

Iris unguicularis (styllosa), the Algerian iris, is renowned as an early flower of spring. It now comes into bloom in late November and very early December, making it an autumn and winter flowering plant. It originates from Algeria, Greece, Turkey, Western Syria, and Tunisia and requires freely draining, light soils with minimal nutrient value. Planted in a south facing border, Iris unguicularis is an undemanding and very colourful addition to the garden. Many early-flowering plants have highly coloured flowers which attract the widest spectrum of insect pollinators.

Pictured above: Cyclamen hederifolium

Similarly, Cyclamen hederifolium (hera meaning “ivy”, folium meaning “leaf”), now flowers vigorously from mid-December, providing colour in the garden in those darkest days prior to the winter solstice. It originates from woodland, shrubland, and rocky areas in the Mediterranean region from southern France to western Turkey and on Mediterranean islands. Once the corms are established it naturalises freely, spreading by self-seeding from explosive seed capsules which cast progeny widely in borders of light, sandy nutrient-free soil.

Pictured above: alyssum (A. saxatile)

The common rockery plant alyssum (A. saxatile), is a perennial herbaceous plant, which rapidly colonises borders and will spread down onto walls providing colour from early January. It is one of the ornamental members of the cabbage family (Brassicaceae) with bright cruciform flowers.

Each of these plants is responding to climatic warming, indicating the loss of traditional seasonality. This impairs relationships between flowering plants and animal pollinators that have carefully evolved for mutual benefit over millennia. The full consequences of these losses will be apparent in years and decades to come.

Professor Geoff Dixon is author of Garden practices and their science, published by Routledge 2019.