Gareth Carter: Treat yourself with an avocado tree

Correct site selection is the biggest influencer of success or failure when growing avocado trees. Photo / 123rf

The gardening page is probably one of more uplifting pages in the news media to be reading at the moment; certainly the business pages give some doom and gloom for the year ahead.

As Covid cases are again increasing, we can plant our own cheer in the garden, creating our own piece of peace and tranquillity. Growing your own groceries is a popular topic of conversation and so many are into it for so many benefits; economic, physical and mental health, pleasure and the sense of satisfaction.

Those who planted vegetables are reaping a harvest now. When it comes to planting fruit trees, we have to plan a bit further ahead. There is a saying “the best time to plant a tree was 10 years ago, the next best time is today”.

So if you haven’t got a few fruit trees around your home, come and choose one today. A fruit that is becoming more mainstream for the home orchard is the avocado.

The avocado has been recognised for its health benefits as well as a wide range of meal and snack options. The reporting of health benefits in the media has also driven avocado popularity. They are rich in monounsaturated oil, proteins, vitamins A and B, while being low in cholesterol and sugar and contain a large amount of minerals.

Correct site selection is the biggest influencer of success or failure when growing avocado trees. They grow best in a warm situation with fertile, well-drained soil in full sun and need protection from strong winds and frost while the plants are young. Once they are established the trees can withstand frost to -2C or -3C.

Avocado trees need a good-sized area to grow. If left to their own devices they will eventually (after about 15-20 years) grow to a tree of about 10-12m high and 4-6m wide.

For those who are keen, avocado trees grow easily from seed but the downfall is they will take up to 10 years to fruit. Trees that are grafted will produce fruit after about four years and after seven years should be producing 200 or more avocados annually.

Many homes do not have a spot large enough to have a tree of this size but, by pruning each year, a much smaller tree can be maintained. Intensive planting and pruning is now being practised by new commercial plantings where traditional tree spacings of 10m apart are now being halved to about 5m. Skilled pruning is undertaken to keep trees maintained at 3-4m high, while not removing the trees’ ability to fruit. This means fruit production is far closer to the ground, reducing the labour input needed at the time of harvest. The high labour input to extract fruit from tall trees is one of the contributing factors to the high cost of avocado fruit relative to other fruits.

Many people know the avocado variety Hass, and to a lesser extent Reed, which are sold widely throughout New Zealand. There are other varieties that should also be considered for the home garden. By planting several different varieties you will not only increase the flower pollination with better fruit set, but you will also have fruit throughout many months of the year as the varieties ripen at different times.

Hass: New Zealand’s favourite avocado, crocodile-skinned tasty fruit. Heavy cropper, fruit mature from September to March. “A” type flowering pattern, cross-pollinated by Fuerte or Bacon.

Reed: Large cannonball fruit, heavy cropper and very nutty flesh. Fruit mature from February to June. “A” type flowering pattern, cross-pollinated by Hashimoto, Fuerte or Bacon.

Fuerte: Very vigorous green skin avocado with some cold tolerance. Fruit mature from September to December. “B” type flowering pattern, cross-pollinated by Hass or Reed.

Bacon: A smooth-skinned green avocado, with fruit maturing July to September. “B” type flowering pattern, cross-pollinated by Hass or Reed.

Hashimoto: Very vigorous green skin avocado with some cold tolerance. Fruit mature June and July. “B” type flowering pattern, cross-pollinated by Hass or Reed.

Zutano: More cold hardy than Hass and the earliest to fruit, ripening in July and August, fruit has a fibrous texture with a higher water content and a lower fat/oil content. Yields well with thin-skinned pear-shaped fruit resembling Fuerte. “B” type flowering pattern.

Ettinger: Plentiful crops of smooth skin, pear-shaped fruit. Lime green flesh has a buttery texture and a nutty taste. Fruit matures from August to October. “B” type flowering pattern.

Sharwil: Creamy with a mild rich flavour, not as nutty as Hass. Oval-shaped fruit similar to Fuerte, the skin is hard. A major commercial variety in Hawaii due to its high quality and exceptional flavour and a smaller stone than other varieties. It fruits for a long time, starting prior to Hass about August, and overlaps with Reed into February. “B” type flowering pattern.

Cleopatra: Medium-sized pear-shaped black fruit with a shiny skin. Yellow creamy flesh of creamy rich flavour. The skin turns black prior to harvest. Larger than Hass fruit. Harvest from July to December. The tree is dwarf in size, growing about 3m high by 3m wide, and compact and bushy in habit. “B” type flowering pattern, cross-pollination with Hass and Reed will improve fruit set.

Pollination

Avocado trees have an interesting arrangement with their flowering. They have been classified into “A” type and “B” type tree varieties. The trees have both male and female flowers on the tree.

“A” type flowering pattern (Hass & Reed): The female opens in the morning the first day for two to three hours and then closes. The male flower opens in the afternoon of the second day for two to three hours then closes. Hence cross-pollination of two varieties helps in warmer climates. In cooler climates, opening and closing of the flower tends to overlap, making them more self-fertile. Cross-pollination should be from a “B” type flowering variety such as Hashimoto, Bacon, Ettinger, Sharwil, Zutano or Fuerte.

“B” type flowering pattern (Bacon, Ettinger, Sharwil, Zutano, Cleopatra, Fuerte & Hashimoto): The female part opens in the afternoon on the first day for two to three hours then closes. The male part opens the morning of the second day. Hence cross-pollination of two varieties helps in warmer climates. In cooler climates opening and closing of the flower tends to overlap therefore making them more self-fertile. Cross-pollination using “A” type flowering variety — Hass or Reed.

During cooler weather, the flowering can be delayed and quite erratic. This can mean the opening and closing of the male and female flowering can overlap, increasing rates of self-pollination. When the temperatures are warm and reach 21C or above the flowering becomes much more regular.

So to summarise, all varieties are somewhat self-fertile but the weather conditions will play a significant part in the amount of fruit set. If you have issues with fruit setting then planting a mixture of “A” and “B” flowering types will increase the pollination.

There is good range of avocado trees available at the moment so why not treat yourself — remember the saying “the best time to plant a tree was 10 years ago, the next best time is today”.

For more gardening information go to www.springvalegardencentre.co.nz

– Gareth Carter is general manager of Springvale Garden Centre