Cold Tolerant Avocado Trees
Bacon avocado is the most popular cold hardy avocado readily available for sale in Australia. Grown in home gardens in Victoria the Bacon Avocado tree produces a medium quality fruit. Readily available although you might need to get you local nursery to order them in for you.
When looking for cold hardy, or cold 'tolerant' avocado trees the group of trees from Mexico are by far the hardiest, these include Bacon, Shepard and the little known in Australia 'Zutano'. However it is not only the tree itself that is cold tolerant, it is also the rootstock, Duke is perhaps the most cold tolerant rootstock of all.
Reed, Hass, Rincon, Fuerte, Ryan and Sharwill are all reported tohave some degree of cold tolerance. Remember that avocados come in type A and type B, they fruit more prolificly if one of both is planted.
Cold however does not mean frost, in general avocado trees do not like frost at all. And in cooler climates drainage in winter is especially important.
Other cold tolerant avocado trees include
Brogdon: a purple to black skinned variety which is very cold tolerant, but not readily available
Lula: A cold tolerant avocado with long harvest period, again not readily available in Australia
Monroe: A nice large fruit, tasty and a cold hardy tree, again not readily available.