Drought
Rubbish, you say, don't you listen to the Today programme? But think about it: all those people in sweltering offices and hospitals will need more energy-hungry, problem-compounding air-conditioning; inadequate water supplies will require new, leak-free pipe systems and reservoirs; melted roads and warped rails will bring transport chaos and vast repair bills. All we gardeners have to do is adapt the way we garden.
Take comfort in the fact that all ecology is flux; no ecosystem, certainly no garden, was ever fixed. We even inflict our own changes on the way we garden, we move house, our tastes change, children come and go. And now the climate is forcing some different, very basic changes upon us. To keep a garden looking good, we must let go some of the old rules (perhaps the old rule books too, however eminent the author); we must watch the changes and respond, and above all we should enjoy gardening in a new way. Otherwise, frankly, what's the point?
Here is the nub of things:
A New Climate
Climate change means that on average it will be hotter and dryer in summer, and wetter in winter, but with more frequent, unexpected extremes of heat, drought, wind and even very occasionally cold. Our grandchildren will think it's normal. Unbearable? Think of Rome in high summer now, think of Wales in the monsoon season.
Timing
Bulbs and spring-flowering shrubs are already starting to bloom before Christmas. Wonderful: we get a longer season of winter flowers. The downside is that there will be less nectar for the insects (and those valuable pollinating insects) when they appear later on.
Spring pruning - of roses, buddleias, clematis, you name it - will need to happen earlier, and that's fine. As long as the last frosts finish earlier too, it won't matter in the least.
Seed may be sown and planted out earlier; but remember there'll be no more hours of daylight in March than ever there were, so plants won't romp away so much better; waiting for the longer days is okay. There's no rush.
Summer Heat
Until now, summers of even temperature meant we could just about get away with moisture-loving or cool-alpine plants in ordinary garden soil; but under extreme heat and drought they will wilt or sulk and we shall have to suit plants much more carefully to their preferred conditions. Check in an encyclopaedia.
Happily, real heat will make it worth planting figs, vines and apricots, and fruit in general will grow better further north. We, on the other hand, will want shade, and we'll need to plant for it.
Water
Lack of water will be the real problem. The soft, lush image of a traditional English garden will have to give way to a leatherier, heat-resistant style, but that's okay: there will be a new palette of plants for gardeners to learn about. Just look for spire-shaped and mound-shaped plants in different species.
We'll have to remember that 'exotic' cannas and bananas actually come from hot, wet climates, not hot dry climates. Are they worth the water? And are those few token vegetables we grow for the feel-good factor worth the watering, or is it actually more sustainable to buy them. And patio pots - thirstier than anything - are they sustainable?
In flower-beds, a water-conserving mulch will be vital and we really need to make the most of water butts.
Pests and Diseases
New pests and diseases will come north, some harmless, some destructive, but don't panic: hot on their heels will be their natural predators (some of those predators may arrive first of course, and invisibly ward off the problem). Until a new balance is reached we will have to be vigilant and ready to deal with sudden new enemies. The flipside: our old pests may actually dwindle or head north, where it's cooler.
Lawns
Lawns already grow all winter and the quiet time to have mowers serviced may soon be August. Watering lawns should already be a luxury of the past, and we ought to settle for brown grass in summer or less open space and more planting; a well-stocked and well-mulched bed is a much richer habitat than a hard gravel garden.
Wind
There will be more gales and mini-hurricanes, so give more thought now to sheltering trees and shrubs. New trees are best planted small, at 3-4ft instead of 6-8ft, if they are to be stable in the long-term.