Our changing climate - an overview
It is true to say that gardeners always have a weather eye out, because much of our forward thinking and pottering about depends on it. Many of us are noticing that weather trends are changing, if only because we are starting to mow the lawn earlier in the spring and continuing later into the autumn than before.
The RHS has produced an in-depth report, Gardening in a Changing Climate, to look at these trends, pointing out the challenges but also the opportunities. It is a detailed read and we are all busy, so we will skip over the scientific evidence and cut to the chase to look at what is happening now and what is predicted for the future. For us, here in Marden, the main trends are:
Temperature - warmer than average conditions and warm extremes (e.g. summer heat waves). Frosts are less likely to occur.
Rainfall - an increase in intensity and frequency of heavy rainfall. Winters are projected to get wetter and summers to get drier on average.
Drier soils - soil moisture is dependent on rainfall, of course, but also evaporation from the soil and and by transpiration from plants. Higher temperatures and less summer rain are leading to drier soils for much of the year.
Variability - A feature of the UK climate has always been variability, and this is predicted to continue with some instances of cooler summers and colder winters, despite overall trends.
Sea level rise - creeping sea level rise and storm surges will be a problem in coastal areas but, fortunately, this is one aspect of climate change that won’t affect our gardens in Marden.
Storminess - higher temperatures mean more energy in the atmosphere which can lead to more intense and frequent storms.
On the basis of all the above it appears that the key risks for gardening are: flooding, water-logging, soil erosion, wetter soils in winter, damage to plants from heavy rain, mild winters (with changes in risks from pests, disease and lack of chilling), heat stress, drier soils, increased need for irrigation and unexpected/occasional spring frosts.
However it isn’t all doom and gloom; there are key opportunities for gardening. These include: a longer growing season, the opportunity to plant a wider variety of species, reduced risk of spring frost, use of gardens/green infrastructure for cooling. Also gardens and green spaces can reduce surface flood risk by helping to store excess water in winter that can be used for irrigation during the summer.
The RHS predicts that in the future our gardens in the South East will look something like this:
Lawns have been converted to meadows. Grass lawns have been replaced in some gardens by artificial lawns, particularly for families where play space is needed. In other gardens, the lawn has also disappeared to be replaced by gravel beds and hardy ‘cornfield’ annuals. Shallow swales and depressions are used to recreate ‘dry’ riverbed landscapes, using gravel, stones and ‘drift’ wood
Down pipes from the house roof are connected to an underground tank to store winter rain water run–off that can be used in the garden during summer.
Trees are planted with a perforated watering pipe penetrating into the rootball to provide deep watering during hot periods. In some gardens these are located in shallow scrapes into which recycled grey water from the Local Authority communal tank can be added when required.
Gardens are screened to the south and west to provide mid–day shade, to help mitigate effects due to dry soil and to give some respite to drought sensitive species.
Patios are used more frequently as outdoor social spaces. Shade is provided by suitable species of plants, where moisture availability allows. Wall climbers, linked to irrigation systems using recycled water, are planted around the air conditioning units of houses to improve their cooling efficiency.
Although water will be a challenging feature to manage due to high evaporation rates, rills, small pools, bubble fountains etc. become increasingly important to provide relief from the heat and dryness experienced in summer. Windbreaks and sheltering walls help to minimise wind movement and the amount of moisture lost from water features.
Colourful patio plantings and window boxes are located close to the house for ease of watering. Plants currently semi–tender become mainstream and flower for longer.
Borders and beds are mulched to reduce soil temperatures and inhibit evaporation. Mulch will include organic materials and inorganic materials such as pebbles, crushed glass etc..
More gardens accommodate a swimming pool to capitalise on the warmer summers.
So, plenty of things to think about as we tend and develop our current gardens, and there is much more detail about climate change, from the RHS report and other sources, for us to explore in the future.