Sun in winter; cool breezes and shade in summer; fresh fruits in frost prone areas – these are some of the benefits of micro-climates. Micro-climates are localised conditions in an area. They can occur naturally or be manmade. By maximising existing ones or creating new ones, you can extend the time you can enjoy outside and also the types of plants grown.
To maximise winter sun, plant all tall trees on the southern boundary. Be careful not to shade out any neighbours. Many neighbourhood disputes stem from trees! Grow plants that require a lot of warmth on the northern side of walls, rocks or taller plants. Light coloured structures reflect heat during the day and dark ones collect heat and emit it through the night. Walls and other structures also block winds, increase humidity and because of their thermal mass, decrease the chance of frosts. Frost sensitive plants can be planted next to ponds and dams. These water bodies store heat during the day and release warm air at night and early morning.
To minimise summer sun, plant lots of umbrella shaped shade trees, especially to the west. Multi-layered gardens also create a cooler micro-climate and maintain soil moisture. Construct shaded walkways that link garden areas. Make the paths out of bark chips, grass or light coloured pebbles as these materials don’t absorb heat.
To protect a property from strong prevailing winds it is important to establish shelter belts before any other planting is attempted. The most effective shelter belt is made from a row of trees and shrubs, which breaks up wind but does not create turbulence.
Wind hardy species are an obvious choice. These can include many native species and ornamental grasses.
Earth mounds, around two metres high, will give protection to an outside sitting area. It is best to plant these with low growing shrubs as mowing can be a challenge! Small gardens can use trellis or netting, which helps to break up any wind tunnelling.
Rain shadow is often experienced in urban gardens. This is caused by walls and other structures. North and west facing gardens dry out due to a shortage of water and their sunny aspect. It is best to improve the moisture retaining capacity of this soil by adding organic matter. Avoid planting right up next to walls and install irrigation.
When assessing a site for the likelihood of frost it is a good trick to think of frost as water. Frost will flow down a slope settling in the lowest area. On a slope plant a hedge above the garden. This will deflect cold air around it. If your garden is on a slope plant the more tender plants towards the top. If the land is flat, frost is more likely to settle where there are no trees.
Water and other types of thermal mass, such as concrete and glass, store heat during the day, slowly releasing it at night. Around these areas, tender plants will experience a micro-climate a few degrees warmer than the surrounding garden.
By considering a few of these issues it is possible to create a micro-climate that will enable you to enjoy the outdoors longer and also harvest fruits that others may not be able to.