Gardening Basics: Climate

Climate has a fundamental effect on the landscape, both within the confines of your lot and more widely in your geographic area. Climate has much to do with the shape of your home, your leisure activities, use of outdoor space and, of course, which plants will thrive in your region. The USDA has developed a useful, though not perfect, map to show different zones where plants of different hardiness will survive. Climate, however, is about more than how cold it gets in winter.

Planning landscape or garden development is well served by careful observation of your local circumstances. Temperature gradients, sunshine hours, rainfall, wind, aspect and topography all influence not only how you use your property, but also how plants grow and how well they grow. It is useful to begin by generalizing – is your climate temperate, Mediterranean, desert, tropical or sub-alpine?

A temperate climate is categorized by a lack of extremes. There are mild winters and cool summers, with noticeable seasonal variations. Spring and fall last as long as summer and winter. In this climate a wide range of plants thrive, including imports native to other climates. Human activity is equally varied, and shows seasonal variation. This climate is found in parts of the eastern United States.

The Mediterranean climate has dry summers and temperatures rise to the high nineties Fahrenheit. Most rain falls in the winter and fall seasons. Spring and early fall are the main growing seasons, with plants lying dormant in the summer. Humans, too, find the summer heat trying – it was in this climate that the siesta was invented. Mediterranean architecture seeks summer coolness. Much of California has a Mediterranean-type climate.

Desert climates are dry, but not necessarily hot. Lack of water is more of a limitation to humans, who cannot easily live there with the meagre ration of water supplied by nature, than to plants, which can. Plants endemic to desert areas have modifications for survival that also give them extraordinary “architectural” qualities. When extra water is provided, as by human-mediated irrigation schemes, both humans and plants may blossom. Large areas of the south-western United States have a desert climate.

Tropical climates are hot, but not necessarily dry. Dry zones include deserts like the Sahara. Humid tropical zones have heavy and frequent rain. The heat and moisture of the humid tropics produce lush and rapid plant growth. Tropical rainforests produce delights such as the orchids and bromeliads among epyphytes, passion flowers among the creepers, and the hibiscus and frangipani among shrubs. Sub-tropical and tropical areas of the United States are the south-east and Hawai’i.

The sub-alpine climate has temperature extremes from sub-zero winters to hot summers; but at the start and end of the growing season there can be great temperature variations even within one day. There are a number of plant adaptations to living in these extremes, such as the needle leaf of the conifer and the abundant mosses of water-logged zones. It is the home of the heather, and the boundary between sub-alpine and alpine is the point where trees stop growing. Human interactions with the climate can be seen in the prevailing architecture and in the leisure activities pursued. Gardening tends not to be a year-round activity. The sub-alpine and alpine climate is found in parts of the north-west United States and Alaska.

This climatic division necessarily takes a wide brush to our gardening canvas. Within the desert climate of the south-west there are rivers, mountains and the sea, all of which create variations on the general theme. All such variations need to be recognized as you develop your landscape design and plan your garden plantings. Yet the wise householder will pay attention to the fundamental conditions that characterize the local climate so that decisions about landscape design and planting plans work with, not against, nature.

‘Sunshine is delicious, rain is refreshing, wind braces us up, snow is exhilarating; there is really no such thing as bad weather, only different kinds of good weather.’ - John Ruskin