Top plant choices for cool climate gardens
Gardens in elevated and inland regions, such as west and north-west Sydney, the Blue Mountains and the Southern Highlands, enjoy cold winters with lots of frosty mornings. These chilly gardens don't suit the lush, subtropical plants that are favoured in coastal gardens. However, they are perfect for a wide range of cold climate plants, many of which are bare and dormant over winter.
Deciduous trees and shrubs
Deciduous trees such as maples and golden ash develop vibrant autumn colours, while blossom trees including the many prunus, as well as deciduous shrubs such as flowering quince (Chaenomeles spp.) and mock orange (Philadelphus coronarius) produce beautiful displays of spring flowers. The floral show from prunus trees and flowering quince often begins in mid to late winter, along with the glorious blooms of magnolias.
The smoke bush (Cotinus coggygria) is a tall deciduous shrub that relishes cold winter conditions, but also thrives in warm summer conditions. Its dark purple leaves regrow each spring, then colour to red and orange in autumn. Its plumes of pinkish spring flowers fade to a grey in summer to give the shrub its common name - smoke bush.
Contrasting with the bare branches of deciduous trees and shrubs are the many cool climate evergreens. Lily-of-the-valley bush (Pieris japonica), rhododendron, azalea, pittosporum, photinia and conifers bring structure to a cold climate garden. Providing year-round green, they act as a foil for the bare branches of deciduous plants in winter and provide shelter from cold winds. Many also flower well into late winter and spring.
Low-growing perennials with winter flowers also bring interest and welcome colour to cool climate gardens. A top choice is hellebore, especially varieties of Helleborus orientalis. Hellebores thrive in the shade of deciduous trees, producing long-lasting flowers that range in colour from green to white, pink, red and even slate.
Deciduous climbers such as wisteria are also a boon in cool climates, as they create welcome summer shade, while allowing winter sun to filter through when the sun’s warmth is welcome. Wisteria’s beautiful and fragrant mauve flowers always herald the arrival of spring.
The key to success with cool climate plants is to protect them through the often-hot summers that these areas can experience. This means providing afternoon shade to prevent leaf burn, and also offering shelter from hot westerly winds that can buffet gardens in summer. Magnolias, maples and hydrangeas are susceptible to sun and wind damage in hot conditions. Use tough evergreens to shelter more delicate plants.
Many cool climate plants also need extra water, especially in spring, when they are growing new leaves and in flower, and also during hot dry summers. Provide a layer of organic mulch mixed with aged manure over the soil to protect the root systems of cool climate plants and keep them cool right through summer.