Why leaves change colour and fall in autumn
Posted on September 11 2019
As seasons change, so do our beautiful hedgerows, gardens, woodlands and parks. All around us we can see the familiar signs of our deciduous trees' natural, glorious transformation. The riot of rich, lush green is now slowly ebbing into hues of yellow, orange and blazing reds.
Autumn is an unpredictable time. We don’t always know what this season will bring, especially when caring for deciduous trees. This period can be bewildering for a novice gardener, but all is well! Having braved many autumns and winters at The Present Tree HQ - we can confidently give some great tips and advice to put your mind at ease this season.
As the days shorten our beloved deciduous trees begin to lose their leaves as part of their natural cycle. As the weather turns chilly our trees face painfully cold temperatures and in order to survive, they reduce to their most essential parts: their branches, strong stems and thick-barked trunks.
The first part of this process will be the leaves’ gradual colour change, so don’t panic! Most deciduous trees actively produce pigments called ‘anthocyanins’ in autumn, this causes leaves to burn brightly with fiery colour and has the ability to lower a leaf’s freezing point. This way, they can be sustained on the tree for longer which maximises the energy and nutrients absorbed by the tree before becoming dormant in winter.
Noticed some falling leaves? A tree’s leaves are programmed to fall by the shortened autumn days; the tree will retain most of its energy within its trunk and branches, so the leaves become dry and flakey, eventually dropping from the tree.
Trees shed their leaves because the winter conditions would damage them and the tree would waste too much energy repairing and replacing the damaged leaves. Just like winter hibernation for many animals, trees have adapted to the annual weather change by reducing their energy out-goings and becoming dormant to survive cold winter.
Fast-forward to spring and the wonder of nature is magical to see. The warmer, longer days of spring trigger an awakening in your deciduous tree. An abundance of fresh leaves unfurl from their leaf buds, its shoots and branches gradually lengthen and soon your tree is magnificently vibrant once more!
Our Top Tip!
Throughout early autumn, stop watering your trees (both deciduous and evergreen). This pause in watering will allow a tree to enter its transitional phase and avoid causing spurts of fresh growth that will not be winter-hardy. Once the leaves start to fall give your trees one last thorough watering before the ground becomes too hard and frosty to allow water to penetrate.