Is Spring Earlier?

While astronomers mark spring with the equinox, and meteorologists with calendar months, nature defines spring through the vibrant resurgence of life – budding trees, blooming flowers, emerging insects, and the return of birdsong. Climate change is impacting the timings of these events, with the signs of spring appearing earlier. But what’s really happening, and what are the consequences of this for plants and all the life that depends on them? 

Are any of us so attuned to the seasons as a plant? The annual rhythms of plant life – think bud burst, flowering, seed production, leaf fall – have evolved over millennia. Plants tune in to changes in temperature and daylight to tell them what time of year it is, and when to awaken in spring, or go to bed for the winter. This cycle underpins biodiversity, supporting countless interconnected species.  

Lesser celandine (Ranunculus ficaria) flowers in spring

 

However, the timing of key seasonal events, like the appearance of leaf buds on trees, is shifting due to warmer winters and more frequent extreme weather events. In spring, this is particularly apparent, with plants and animals emerging from winter dormancy at increasingly unpredictable times. Observations collected through the Woodland Trust’s citizen science project, Nature's Calendar, show climate change is causing UK plants to flower a month earlier on average in the UK, and the beginning of spring is now happening on average 8.4 days earlier than in the period 1891-1947.  

Tree seeds need a chill 

A cold winter may not feel very welcome to us, but it helps UK tree seeds enter the process of dormancy before they germinate and grow in spring. This ‘chilling period’ prevents seeds from germinating too early, during brief warm spells, when conditions are still too harsh for young seedlings. 

Warmer winters caused by climate change mean that sometimes tree seeds don’t get the chill they need, particularly in the warmer southern regions of England and Wales. Seeds such as birch and alder are more likely to sprout too early, and be more vulnerable to late frosts, or too late, facing drought. Sometimes, they might not germinate at all. Many tree seeds, such as holly, juniper, and hawthorn, require specific temperature sequences, like alternating warm and cold periods over several months or years, to break dormancy and germinate.

Scientists at Kew's Millennium Seed Bank are studying how seeds from different UK regions respond to varied temperatures and chilling periods. This helps target conservation and restoration efforts where they’re most needed, and to plan for climate-resilient forests of the future.  

Read more about how climate change impacts trees and forests on the RBG Kew website.

 

Species out of sync 

Some species react to changing temperatures faster than others. This means that climate change can cause plants and animals which usually rely on each other to fall out of sync, disrupting their natural interactions. For example, in response to changing temperatures, many pollinators such as bees and butterflies are emerging even earlier than the flowers they rely on. This can create what’s known as an ‘ecological mismatch’. 

The early spider orchid attracts male solitary bees to its flower by mimicking the look and smell of a female bee.  

The first orchid to appear in the UK in spring, the early spider orchid (Ophrys sphegodes) attracts male solitary bees to its flower by mimicking the look and smell of a female bee. When the male bee tries to mate with the flower, pollination occurs. Rising temperatures mean male bees emerge earlier, before the early spider orchids flower. This mismatch, documented since 1848, reduces pollination success, threatening both species. 

Mismatches between plants and pollinators can impact a whole web of biodiversity. For example, research using data from Nature's Calendar shows winter moth eggs can hatch prematurely, before oak leaf buds open, leaving them without food to survive. This affects blue tits, which need up to 1,000 caterpillars daily for their chicks. 

Plant and pollinator mismatch also impacts our own food supply if crops cannot be pollinated, as well as the health of our ecosystems more broadly. 

 

Spring into action!  

While the changes we're witnessing are significant, they also present an opportunity. By joining citizen science initiatives like Nature's Calendar, supporting local conservation efforts, and making mindful choices in our gardens, we can all help build a more resilient and biodiverse future. 

Take part in Nature’s Calendar to record wildlife near you 

From leaf buds bursting to blackberries ripening, let Nature's Calendar know what’s happening near you. Every observation contributes to a larger understanding of how climate change impacts timing in nature and helps conservation efforts. 

Start recording now 

Get growing!  

Gardens and green spaces are vital for reducing the impacts of climate change. Plant a diverse range of species, including drought tolerant and native plants, to boost resilience against extreme weather and support local wildlife. A longer growing season means more opportunity to include a diverse range of plant species in your growing space. 

Read more about adapting your garden to a changing climate.  

Bethnal Green Nature Reserve. Image credit: Ines Stuart-Davidson © RBG Kew