A climate-change fuelled dry summer and mild autumn have confused plants, resulting in flowers blooming early and leaves not falling from trees, experts have said.
October 2022 in Ireland was the 17th consecutive month that was warmer than normal, according to Met Éireann.
Peter Dowdall, a gardening expert and horticultural consultant known as The Irish Gardener, said the consistent trend of warming has resulted in an “exceptional” increase in the number of plants flowering at unexpected times.
“Even in my own garden you’re looking at three or four different flowers which you’d never see at the one time. Some should be spring, some should be autumn, some should be summer, and they’re all flowering in my garden right now,” he said.
“A lot of spring-flowering plants would be the likes of camellias, rhododendrons, azaleas, magnolias. All of these plants would set their flower buds now for flowering next spring, but because of the mild temperatures now they actually think we’re in spring already.”
Mr Dowdall said that while people might enjoy seeing these flowers in other seasons there is a “more serious issue at the bottom of it”.
“Obviously it’s caused by climate change, but it’s in the spring of the year that it will lead to a problem. It leads to what’s called an ecological mismatch. Everything is connected in nature. If you’ve got an apple blossom flowering at the right time that the bees are coming out of hibernation, they pollinate the apples, the apples feed the humans, the seed grow new trees that provide refuge for the birds.
“So if the apple blossom flowers too early, the bees and other pollinating insects aren’t out of hibernation. When they do come out their food source is gone so the bee population collapses even further.”
Dr Eoin Lettice, lecturer in plant sciences at University College Cork, said plants take their cue on when to grow from what is around them such as temperature, precipitation and the length of the day.
“The large lime trees outside my window are still holding on to a lot of their leaves. Some have turned yellow and are falling. Normally these leaves would be gone at this stage but because the temperature hasn’t dropped they’re just holding on that bit longer. As a society we expect plants to behave in a certain way and according to a certain sequence. That is now changing, becoming a bit more fluid. What we’re seeing is the visible face of climate change. It is manifesting in our parks and gardens.”
A study by Cambridge university, published in February, found the effects of climate change are causing plants in the UK to flower one month earlier than they did before 1987.