Avocados are wonderful fruit trees for the home garden. They are easily propagated from seed, however seedlings are unreliable and grafted plants from the nursery are a much better option. Grafted trees grow around 10-12m (30-35’) tall, but seedlings may reach 30m (60’) tall. Seedlings take around 15 years to mature and bear fruit, while some never bear fruit at all.
Strange sex life
Don looked at a mature tree that was producing tiny little fruit. He explained that this was a pollination problem, and that avocados have a curious sex life.
Some avocados (known as group A) have flowers that function as female on the first morning they open. When they reopen on the afternoon of the next day, they are functionally male. Opening and closing of the flowers is synchronised in all trees of the same variety. Other varieties (known as group B) have flowers that open on the afternoon of the first day as female, then close and reopen the next morning as male.
In warm areas of Australia two trees are needed for pollination to take place. In cooler areas the opening and closing of the flowers is not so well synchronised, so there is enough overlap for pollination to occur on solitary trees.
Nature’s fridge
Avocados do not ripen on the tree. Harvest fully formed fruit whenever you want, then ripen them indoors. (Tip: if you harvest fruit with a piece of the stem attached the fruit will keep for a longer period.)
Further information
Grafted avocado trees are available in nurseries from spring. A plant in a 5 litre bag or 200mm (8″) pot will cost around $25, and will fruit in about 2 years.