While it is interesting and challenging to grow plants beyond the range of their cold tolerance, it increases the risk of frost damage and creates more work in protecting them – taking them indoors in winter, for instance. It is important to be aware of how the local climate behaves in the garden.
Avoid plants that do not tolerate frost
The nearer the garden is to the coast, and the further south, the longer the growing season and the less likely there will be severe winter frost. There are many plants that will survive light frost down to minus 5º Celsius and will suffer below minus 7º Celsius. The chances of going below this temperature increase dramatically inland and further north.
Try to find out exactly how frosty the area is by looking at other gardens. Plants like cordyline, hebe, fuchsia and pittosporum are good indicators of the relative mildness of the area. If they have grown to good size, the winters much be fairly consistently mild. If they are completely absent, the locality is prone to severe frost.
Because of the warming effect of the sea, it is possible to grow plants in coastal gardens that would not survive inland, although wind damage near the sea is generally more severe.
The damage caused by winter cold is influenced by other factors. Warm sunny summers encourage the development of tough woody growth and high sugar content in plant cells. Freezing will not occur until lower temperature levels are reached.
Plants growing in free-draining soil will have a longer growing season and complete their preparation for winter earlier than those on heavy soil. Plants growing on south-facing slopes suffer less because the extra warmth encourages better development of tissue.
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