See Mark in the October edition of Gardeners’ World Magazine
Windy gardens: Mark Lane explains how to prevent wind damage in autumn
When a large tree is torn down by the full force of a gale, it seems to do so in slow motion. At least, that’s how I remember it one night during the stormy winter of 2013-14 when, after the initial cracking noise of the tearing rootball, our 20 m tall eucalyptus was ripped from the ground by one of that year’s many gales and dumped onto our herbaceous border – 17 years of growth gone in minutes.
For its energy and speed, it showed how wind is one of the gardener’s worst enemies. Strong winds cause plants to sway excessively, pulling and tugging on their roots, the continual movement interfering with the roots’ ability to remain grounded so the plant is partly lifted out of the ground. This is called ‘root rock’ and it stops the plant absorbing water, leading to severe water stress and even death. Strong winds also distort growth and lower
the air temperature around plants, reducing their growth rate. Wind-blown rain spreads fungal spores from infected plants to healthy ones, quickly inhibiting their ability to sustain healthy growth. Pollinators can be deterred from visiting a windy spot, too, finding it hard to get a purchase on flowers that are moving. Transpiration is the process by which moisture is carried through plants from the roots to small pores on the leaves, where liquid water changes to vapour and is released in to the atmosphere. It is essentially the evaporation of water from foliage, and wind is a great contributor to transpiration, speeding it up and drying plants out. During autumn and winter, evergreen plants that have retained their leaves are prone to wind scorch damage (when leaves become desiccated), caused by cold winds. These also dry out the soil, compounding the problem.
Minimise the effects: Gardeners are not helpless in the face of autumn gales. Cut back plants that are prone to wind rock, such as shrub roses, lavatera and buddleia, by a third to one-half of their height this month and bring vulnerable ones like olive trees indoors if you can. Pick fruit before it’s blown down and put mulch on the ground to stop water loss from the roots and soil. In the long term, wind can be redirected or slowed down by a windbreak or shelterbelt. A hedge, tall trees, a woven-willow hurdle or a semi-permeable barrier erected across the direction of the prevailing wind will reduce damage. Windbreaks minimise the velocity of the wind and create a favourable micro-climate and shelter for pollinators. Shelterbelts, where tall trees are planted in three or four staggered rows, are suitable for larger gardens. Choose robust trees and shrubs such as field maple, hornbeam, Japanese roses, Austrian pine or bamboo.
Most plants need exposure to some wind to function well, and the key is to shelter them from excessive amounts. Those that rely on wind for seed dispersal and pollination have adaptations such as small, light pollen grains and feathery stigmas to catch them. Air circulation is also essential for preventing a build-up of the damp conditions that lead to the fungal diseases that many plants are prone to, while most plants are strengthened by some exposure to moderate air movement around them.