How to Grow Avocados

Avocados are a popular and versatile super fruit which can be used in many meals. Given the right conditions they are not a difficult tree to grow, but they do take patience. It will take about four years for a new avocado tree to fruit, but once it does you’ll have a good supply of fresh avocados. This guide will show you how to grow and maintain your own tree.

Plant Type

If you buy an avocado tree in store, they will always be a grafted variety. These will start producing fruit from year four onwards. And after seven years it should be producing 200 or more avocados annually.

While they grow easily from seed, they can take up to ten years to fruit, or sometimes never do. So therefore it is always recommended to use a grafted avocado tree.

Varieties

Hass: This is New Zealand’s favourite avocado. It has a familiar oval shape, with thick, pebbly crocodile-skinned tasty fruit, that darkens when ripe. It is a heavy cropper, and the fruit matures from August to May. It has an ‘A’ type flowering pattern, and is cross pollinated by Fuerte or Bacon.

Reed: Large and round with thick, pebbly skin that stays green when ripe. Heavy cropper, with very nutty flesh. The fruit matures from February to June. It has an ‘A’ type flowering pattern, and is cross pollinated by Hashimoto, Fuerte and Bacon.

Fuerte: Pear shape with thin, smooth green skin that is not shiny and remains green as the fruit ripens. It tolerates some cold. The fruit matures from July to October, and has a ‘B’ type flowering pattern, cross pollinated by Hass and Reed.

Bacon: A smooth skinned green avocado, with fruit maturing July to September. It has a ‘B’ type flowering pattern, and is cross pollinated by Hass and Reed.

Hashimoto: A very vigorous green skin avocado with some cold tolerance. The fruit matures during June and July, with a ‘B’ type flowering pattern, and is cross pollinated by Hass and Reed.

Pollination

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

All varieties are self-fertile but the weather conditions will impact the amount of fruit set.

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 they ripen at different times.

‘A’ Type Flowering Pattern (Hass & Reed)

• These are better for the South Island.
• The female flower opens in the morning of 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.
• Cross pollination of two varieties helps in the warmer climates.
• In the 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 or Fuerte.

‘B’ Type Flowering Pattern (Bacon, Fuerte & Hashimoto)

• These are better for the North Island
• The female flower opens in the afternoon on the first day for two to three hours then closes.
• The male flower opens the morning of the second day.
• 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.

Having both ‘A’ and ‘B’ type avocado trees can increase the overlap time of male and female flowers increasing the opportunity for pollen transfer and pollination.

Timing

Plant in spring, as the soil temperature rises and the likelihood of rain lessens. This helps prevent against root rot when establishing the tree.

Location

Location is the biggest influencer on 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 both strong winds and frost while the plants are young.

Once they are established the trees can withstand frost to -2o or -3o and are relatively salt hardy.

They can grow up to 12 mtres high, so choose the right spot carefully and check the variety you’re planting.

Soil

Avocados don’t like the soil too wet, so avoid areas prone to flooding. If it’s too wet, you’re likely to get root rot. So choose a well-drained area.

If you find any clay, add some gypsum to your soil to help break it down.

Planting

• Dig a hole large enough to fit the root system. The hole should be just wider and deeper than the bag.
• Check the depth of the hole is correct by placing the tree, still in it’s bag, into the hole. The top of the potting mix should sit 1 – 2cm above the surrounding soil.
• Wet the soil around the hole prior to planting.
• Submerge the base of the tree in a bucket of water and seaweed tonic fully submerge for a few minutes until all the potting mix is soaked. This will help to prevent transplant shock.
• Cut off the base of the bag and remove it, being careful not to cut the root system.
• Cut along the side of the bag from the base but not quite to the top. Place the tree and bag into the hole and orientate the tree so that most of the leaves face north to shade the trunk as much as possible. The top of the potting mix should be 1-2cm above the rim of the hole.

• When settled, carefully fill the remaining space around the outside of the tree with soil, sliding the bag upwards as the hole is back filled with soil. Be very careful not to damage the roots as they are very fragile. Sliding the bag up as the hole is filled will ensure the potting mix doesn’t fall away from the roots.
• Once you’ve filled the hole, gently pat the soil with your hands to settle it firmly around the potting mix. Avoid stamping the soil too firmly or with your feet as this can damage the roots and avocado roots like loose soil to grow into.
• Soak the soil 40-50cm around the tree immediately after planting. Avoid water pooling around the trunk.
• Add mulch.
• Because they are shallow rooting, stake well using the double stake method. The stakes should support the tree but also allow some small movement of the trunk to enable it to develop the strength needed to support its canopy once the stakes are removed.
• Ensure the stakes are hammered into the ground outside the trees root system.

Shade Shelter

It is also recommended to create a shelter using 4 battens and some shade netting to protect the young trees from our harsh New Zealand sun.

Individual shelters are usually constructed from 50mm x 50mm ground-treated battens forming a 1.25 m square with shade cloth on the four sides.

This will allow adequate protection for one to two full growing seasons. The height of the battens should be 1.5 - 2.3m long, which allows for 30-50cm burial of the batten and 1.2 - 1.8m height for the shelter.

The enclosure should reach the ground to prevent damage from rabbits, possums, or beetles. The shade cloth is usually stapled to the battens leaving one side that can be unhooked for access.

Watering

Years 1-2

• Keeping the right amount of water in the soil for young trees is important. Apply just enough water to wet the surrounding soil to a distance of at least 40 to 50 cm away from the potting mix and allow for excess water to drain.
• Watering in the first weeks should be more frequent because most of the roots will still be growing in the potting mix, which can dry very fast. As roots start to grow into the soil around the potting mix (which can happen as soon as 4 to 5 days after planting if soil temperatures are high), watering can then be less frequent.

Years 3+

• Once fully established mature trees water requirements can be often be met by normal rainfall.
• If your soil is particularly free draining, keep an eye on it and water if needed.
• Watering your tree during a particularly dry period can be beneficial.
• When watering your tree, soak the soil inside the dripline well and then allow it to dry out before watering again in 7-10 days.

Feeding

Years 1-2 (Establishment):

• Spray leaves with a balanced liquid fertilizer every 1 to 2 months after planting to help get the tree get established.

Years 3+ (Fruiting Time):

• After 3 years, use a slow release citrus fertilizer a couple of times a year around the base of the tree, taking care not to make contact with the trunk.
• Increase the quantity of fertiliser as the size of the trees increases. But in winter half the amount fertilizer.

Maintenance & Pruning

Add mulch around the base of the tree to help conserve water, improve root growth, provide nutrients, reduce stress on the tree, and supress weeds.

There are no set rules when it comes to pruning avocado trees. Your pruning should aim to maximise the amount of light the tree gets and also manage tree size and shape. Avoid any major structural pruning in summer to prevent sunburn.

Remove deadwood at any time.

Pests & Disease

Heavy or wet soil can cause root rot, but other than that avocados are relatively pest and disease free – but if you have any questions, come see us in-store.

Harvesting

The main harvest season for avocados is September through to April.

Avocados normally fruit every second year, and the amount of fruit they produce can vary from season to season.

Unlike most fruit, avocados only ripen once picked – but if you pick them before they’re ready, they’ll stay rock hard. Once they’re at the right size, the best way to check is to pick one and see if it ripens up. If they do, you’re good to go.

If your fruit drops before it is ripe in early or late summer, your fruit probably has weak or defective seeds. The tree should produce more later in the season. If you have problems with your fruit setting, try planting a complimentary type to help with pollination. So plant a type ‘B’, if your existing tree is a type ‘A’.