Casual Gardener: Let's learn to love leaves

In a woodland or forest, fallen leaves pose no problem whatsoever
In a woodland or forest, fallen leaves pose no problem whatsoever In a woodland or forest, fallen leaves pose no problem whatsoever

Belfast City Council has a plan to plant one million trees by 2035. Undertaken with a range of so-called partners ranging from the Woodland Trust and Conservation Volunteers to the PSNI and Invest NI, the council is currently on the look-out for locations that can accommodate anything from a handful of trees to a small woodland. So far, some 63,000 trees have been planted across the city.

It's a commendable plan that will help redress centuries of deforestation across Ireland. The island's north-eastern six counties are said to have the lowest density of woodland in Europe, with less than 10% of land area forested, compared to upwards of 13% in Britain. The council scheme aims, among other things, to reduce carbon, improve air quality, reduce flooding and boost biodiversity. Trees enhance the look of an area – think 'leafy suburbs' - and generally improve physical health and mental wellbeing.

My only reservation about planting so many trees in a city is leaves – specifically fallen, dead leaves on hard surfaces, such as roads and footpaths, where they become a hazard. As we saw this week in south Belfast, they also block culverts and drains, increasing the likelihood of flooding. 

Diverse in colour, size and shape, the leaf's role is to turn the energy of the sun into food through photosynthesis. At the end of summer, with the shortening of daylight hours, deciduous trees prepare for winter dormancy. Hormones trigger the abscission process which sees the production of chlorophyll, the substance that gives plants their characteristic green colour, slow and the leaves turn colour. 

The vessels that transport water and sugars from the leaf to the rest of the plant are closed off, and a layer of cells, known as the abscission layer, grows at the end of the leaf stalk where it meets the wood of tree, causing it to drop off with the first stiff breeze. If this didn't happen the water inside the deciduous leaves would freeze in cold weather, rupturing the capillaries. Shedding leaves also makes the tree less susceptible to wind damage. 

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In a woodland or forest, fallen leaves pose no problem whatsoever and are in fact part of a natural process which sees decayed organic matter recycled and the nutrients drawn back up into the tree via the roots in subsequent years.  

Don’t get me wrong – I’m always on the side of the trees but in urban areas in autumn they are high maintenance. Likewise in the garden, the leaves need to be removed from footpaths, driveways and drains. In the latter context they are easier managed - but please let’s not speak of leaf blowers. 

Leaves are a great garden resource if harnessed, especially by the non-antisocial methods of brushing and raking. When composted correctly and turned into leaf mould they form the basis of good, peat-free growing medium that’s especially useful as a potting compost. Decaying leaves can also be applied directly as a mulch to beds and borders. 

If you don’t plan utilising your leaves but need to get rid of them, consider piling them in a quiet corner of the garden where they’ll provide food and shelter for all sorts of creatures. As a last resort, put them in the organic waste bin for collection.