Grevilleas can be grown in most temperate and sub tropical climates. Most do prefer temperatures not much below zero, and can suffer in extremely hot, dry or wet conditions; but there are some species that are more tolerant of extreme conditions than others.
When you choose the right cultivar you can grow Grevilleas anywhere from England to California and Israel to Japan.
Water
There are some species that have tolerated periods of wet and poorly drained soil, including:
G. barklyana
G. bipinnatifida
G. conferifolia
G. diminuata
G. juniperina
G. lavandulacea
G. rosmarinifolia
G. shiressii
Most will respond to being watered, particularly when first planted, if conditions are hot and/or windy. Be sure the soil does not become waterlogged – do not over water. Once a plant has established a deep and extensive root system; irrigation is usually unnecessary (except possibly in years of extended drought).
Temperature
Most Grevilleas come from places where temperatures rarely drop more than a few degrees below zero (Celsius). You can get an indication of a plant's likely cold-tolerance by looking at where a species or cultivar originated. Limited research on the subject would suggest many Grevilleas from temperate climates may tolerate temperatures down to minus 4°C, but they could suffer at temperatures below that.
The following species have been grown successfully in parts of the UK where temperatures can reach minus 10°C or lower:
G. acanthifolia
G. australis
G. juniperina
G. rosmarinifolia
Rodger Elliott and David Jones (Encyclopaedia of Australian Plants) suggest the following are hardy to minus 7 degrees Celsius:
G. acanthifolia
G. aquifolium
G. australis
G. 'Canberra Gem'
G. 'Clearview David'
G. x gaudichaudi
G. ilicifolia
G. juniperina
G. lanigera
G. lavandulacea
G. rosmarinifolia
G. victoriae
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