Justin Newcombe sings the praises of an avocado tree in the garden.
One of the only fruits in nature to produce mono-unsaturated fat, the avocado represents an excellent opportunity for the home gardener to feed themselves. It's prolific too: a five-year-old tree is capable of producing 60 kilos of fruit.
The avocado is a subtropical tree (more tropical than sub, really) originating, like so many of our favourite foods, in Central America. There are A and B types of avocado: the difference is primarily in flowering. Most of the avocados grown in New Zealand are from the A varieties, including the most common, Hass and Reed. Hass is the most popular because the tree has what is known in the industry as excellent fruit hold. This means fruit can be left on the tree for months, picked and then left to ripen inside as required.
With avocados, the trickiest part is pollination. The flowers open for only three hours every day, then close again. But if the temperature drops below 21C, flowering becomes erratic and so does pollination. Root stocks are very important and are the main reason growing an avocado from seed is usually a waste of time. The top part, or scion wood, must be grafted on to a root stock.
The avocado is a handsome looking tree and would be well worth growing for its landscape value alone.
They are big trees, but miniature avocados are available which still have very high yields. My Hass avocado is on grafted root stock and in its fourth season. After no fruit the first year and only one or two the following year, things picked up in year three with around 20 fruit. This year we have almost a hundred.
The avocado has a kind of 18-month cycle which means once the trees establish, yields will fluctuate being heavy one year and light the next. So to maximise yield over two seasons, increase your fertiliser inputs just before the flowering of a heavy yield year, then decrease your inputs at the beginning of a light one. Avocados are gross feeders so we apply heaps of chook poo, seaweed and a good dressing of blood and bone and gypsum, and mulch with pea straw.
Generally the avocado is very easy to take care of, but it does have one great weakness, its root system. The tree's delicate, shallow roots require a free draining alluvial soil as they're susceptible to phytophthora cinnamomi, a fungal infection attacking the roots. I planted our avocado in our chook run. At first the tree stressed a bit because the chooks scratched the roots up when they were foraging through the mulch, so I fenced the tree off and it has never looked back. If you're planting an avocado in heavy soil, address your soil conditions before you plant your tree. Add calcium to the soil in the form of gypsum to help combat phytophthora.
New trees come in an unusually tall bag. Take great care when planting an avocado not disturb the roots, and newly planted trees need to be carefully staked. Because the avocado has an extremely vigorous growing habit, heavy pruning may be required. Plant on the south or western side of your property, in a sunny position - a good idea so that the shade is good, not a nuisance to the rest of the garden.
These trees can easily be integrated into most planting themes, especially subtropical and native. Pair that with massive fruit yields and a no-nonsense maintenance regime and that's some pretty smart gardening.By Justin Newcombe Email Justin