One common misconception of hedge laying is that it is the ‘green’ alternative to hedge trimming. In reality, these practices represent different stages of a hedgerows lifecycle. Both can be used together for optimal hedgerow management.
Every hedge will need occasional (perhaps once in a lifetime) rejuvenation through laying or coppicing. This increases the stem density by encouraging multiple shoots from each stem, thickening a hedge up from the base. It resets a hedgerow into a whole new lifecycle so if done periodically it will hugely lengthen the life of a hedge.
If there is no trimming: Whilst you can leave a hedge to grow without trimming until it requires laying again, this is not appropriate for all hedgerows. Firstly, hedges without trimming will need laying again much more quickly, which can make this an expensive management option. Secondly, without any trimming, the hedgerow doesn’t tend to put much lateral or branching growth. Instead, each shoot competes with each other for light and races straight upwards with straight stems and no branching density. Whilst this may be good for a hedgerow used as a source of wood fuel, it does not provide as many of the co-benefits that a dense hedge will, such as a dense thorny protection for birds nesting.
Trimming creates density of growth in hedgerows by removing the growing tips. This adjusts the balance of hormones in the plants, which are the factors that control the shape. Removing the growing tips removes the hormone that inhibits lateral growth, so you end up with more branching and more density to your hedgerow.
If there is no rejuvenation: There are two different dynamics that can occur by either over-trimming or neglect of a hedge.
Example A: If a hedgerow is trimmed to the same height and shape repeatedly with no periodic rejuvenation, the base becomes hollow, the hedge loses stem density as stressed plants are lost, and eventually the hedge will thin and become gappy. Unfortunately there are examples of what happens to a hedge without rejuvenation all over the countryside.
Sensitive hedge trimming, such as ‘Incremental trimming’ and relaxed trim regimes will slow this process, but even with the best hedge trimming practices in the world, a hedge will always need rejuvenation at some point. No hedgerow can be trimmed indefinitely without seeing structural decline and eventually loss.
Example B: An untrimmed hedge will eventually simply grow to its mature height and eventually quite possibly collapse with age. It will no longer have a dense structure for wildlife and will no longer act as a stock proof barrier. If a hedge is coppiced in its old age many stems may not sprout again and an old hedge may simply be large to lay. Rejuvenation must occur before the hedge is too mature.
Laying and trimming together: So there is no conflict between hedge trimming and laying; when done sensitively these practices complement each other and can grow fantastic hedgerows. Laying will reset the hedge, thicken it up from the base and grant it another life-span. Subsequent sympathetic trimming will encourage branching and density to your hedge, and extend the period of time till it needs rejuvenating again. Depending on your trimming regime and your priorities, this could be anything from 30 up to 40 years.
Click here for more information on managing hedgerows according to their lifecycles