Understanding your garden’s conditions and the local climate are key aspects in attempting to assess how a changing climate may affect it in future.
Along with the soil, knowing the climate in your garden is essential in understanding what plants can be grown, and when to carry out tasks. The main factors affecting the climate are: wind (including strength, direction and frequency), rainfall (how much and when in the year it falls), frost (how frequent and how cold) and how much sunshine reaches the plants. These factors vary from area to area, but are also profoundly influenced by local topography, shelter, and which way the garden is orientated. It is these additional factors and the way they interact that create each garden’s microclimate.
Getting started
You can get an idea of your local climate by logging on to the Met Office website. Look at your area on the ‘mapped averages’ links for air frost, rainfall and hours of sunshine. These show it is generally colder down the centre of the UK as well as in the north; it is relatively frost-free in south-west England and around the coast; large urban areas are significantly warmer than the surrounding countryside; the west of the country can be three or four times wetter than the east; and the most sunshine can be expected in southern and eastern England.
Examining your garden
Once the general conditions are known, assess what your microclimate is like. South- and west-facing gardens are warmer than north- or east-facing plots. Trees, hedges, fences, walls and buildings provide shelter from the wind, but cast shade. Solid barriers can create turbulence, which buffets plants and causes leaf scorch. Shady areas and north- and east-facing walls will be colder. Likewise, fences and walls at the bottom of slopes, and dips and hollows, can accumulate cold air in winter, turning them into frost pockets. In contrast, south-facing walls retain heat in the day and then give it off at night, giving tender plants extra protection.
Just how cold night-time temperatures can get is easy to discover with an inexpensive maximum/minimum thermometer, which can be moved around the garden to discover its real hot and cold spots.
Limitations
To a large extent, there is no substitute for a gardener’s experience of their own plot. Events such as flooding and hard frosts may only occur every five to ten years, and it is these that will set the limits of what can be regarded as truly hardy plants in your garden. Rain gauges, thermometers and soil moisture meters are useful, but several years of data are needed to draw firm conclusions – and we are faced with a climate that may be changing rapidly. Look at what grows in local gardens (as this shows what should do well in yours) and be flexible: we must all adapt.
More information
Become a RHS weather watcher! Find out more here.