How to grow avocados

Can’t get enough avocado? It’s time to grow your own supply. Words Diana Noonan

Varieties

Although there are around 500 varieties of avocado in the world, New Zealand grows just five of them. Of those five, three are our main producers, and only one (the ‘Hass’) is exported. The other big players are ‘Reed’ and ‘Fuerte’.

‘Hass’

Kiwis are most familiar with the ‘Hass’ avocado because 95 per cent of our plantings feature this variety. ‘Hass’ avocados have a definite pear shape and a bright-green ‘alligator-like’ skin when picked. As they ripen, their skin acquires a deep ebony gloss. While some ‘Hass’ arrive a little earlier, they are most plentiful from the start of August and remain available right through until May.

‘Reed’

‘Reed’ avocados are available from February to June. Large, round and uniform in shape, they are perfect for slicing and arranging on a platter. Like the ‘Hass’, ‘Reed’ has a bright-green, pebbly skin. However, it differs from the ‘Hass’ in that it doesn’t change colour as it ripens. This can make selecting ready-to-eat ‘Reed’ avocados a little difficult.

‘Fuerte’

Very similar in shape to the ‘Hass’, the pear-like ‘Fuerte’ has a smoother skin than its lookalike cousin. But when it comes to texture and flavour, it is less creamy and more watery than the ‘Hass’, and sweeter than our other avos. Like the ‘Reed’, the ‘Fuerte’ doesn’t change colour as it ripens. It is available from July to October.

Growing tips

Even in warm parts of the country, planting any earlier than late spring risks placing the tree into soils that are too cold and wet to give the avocado the start it needs. However, if you live in a cooler region, it can be best to leaving planting until summer. By this time, soils will have well and truly warmed up. When planting in summer, it is important to water your avocado regularly, especially during dry spells, as this will help lock in the moisture, and keep the new planting’s roots cool.

Preparing your site is paramount. Ensure the planting place for your avocado tree is frost-free, well-protected from wind, and warm and sunny. Your tree will also need free-draining soil to a depth and width twice that of the container it arrives in, because it has a long taproot.

Avocados won’t grow in clay – in fact, clay may attract fungal disease to the sensitive roots. If clay is all you have, bring in the digger (or some strong arms) and ship in some suitable soil.

If you’re concerned about winds, stake the tree by hammering three supports into the ground before you plant so you don’t damage the tree’s sensitive roots. Attach the tree to the supports with soft bands.

At planting time, avocado trees require fertilising only if the soil they’re planted into is lacking in nutrients. (If you suspect the ground is poor, add citrus fertiliser to the planting hole, mix it in well and ensure it does not contact the tree’s roots.)

Pollination and production

Avocado trees hail from South America, which is why we can’t expect them to be 100 per cent co-operative when it comes to pollination in our fickle maritime climate (research has shown that in Kiwi orchards, only three flowers out of a thousand produce fruit!). More importantly, avocados actually work to protect themselves from self-pollination (even though they are capable of it). In the space of a day, flowers can change from female to male or vice versa, depending on variety. To achieve the best pollination in our challenging conditions, growers import bees into their orchards at pollination time and grow at least two varieties of avocado. ‘Hass’ (known as a ‘type A’ avocado) is the main tree grown, and it is interplanted with a ‘type B’ avocado (such as ‘Fuerte’). Even with all this assistance, avocados don’t fruit well or consistently. All going well, they will produce a heavy crop one year, and a lighter one the next. ‘Hass’ in particular are affected by changing weather conditions.

Nurturing

As it grows, your tree will appreciate foliar feeding (via a leaf spray of balanced liquid fertiliser in the first two months after planting). Following this, compost (enriched with aged animal manure and seaweed), or a granular fertiliser, can be added to the surface of the soil (out to the dripline of the tree) during the active growing period (keep any compost or fertiliser well away from the trunk of the tree). Avocado trees are boron-hungry, and this mineral can help significantly with the tree’s flower-to-fruit ratio, as well as fruit development. It should be applied as a foliar spray prior to flowering.

If your avocado doesn’t already have natural shelter, provide this in the form of shelter cloth (pitched several metres back from the tree). Treat this shelter as temporary (relying on it for 2–3 years). In the meantime, get cracking on planting fast-growing shelter trees (‘Hass’ avocados can grow to 9m, so a shelter tree such as Phebalium ‘Limelight’, which is tall but narrow, is ideal).

If you live in a region where successfully growing an avocado is borderline, consider wrapping young trees in frost cloth for the first four years of their life (they are hardier once they are more mature).

Once the tree is well-established, it will require little attention. Pruning can be carried out to keep the tree well-shaped and to a manageable size. In spring, light pruning can encourage growth. Take care, though, because fruiting occurs on new wood.