Our supplier has kindly provided some answers to the most frequently asked questions on how to grow Avocados…
What are the best conditions for growing avocados?
The three most important things needed are:
1. Free draining soils. There are many soils which satisfy this from sandy soils, to volcanic clays, to ash and many in between. If in doubt, dig a hole 600mm deep, fill with water and ensure it is empty within 12 hours.
2. Temperature. Nowhere in New Zealand is too hot but many locations are too cold. If you get temperatures below minus one, then it is going to be difficult to get trees established. Young trees need to be well sheltered.
3. Water. New Zealand is one of the few countries in the world where there is commercial growing without irrigation. However, in a drought trees will struggle and do much better with a timely drink.
Do I need different varieties for cross pollination?
Different varieties in a cold spring is definitely an advantage. However, in a ‘normal’ spring, avocados are predominantly self- fertile. So, if you are planting an orchard, we recommend 11% ‘B’ type flowerers. If you are planting three or four trees, it is well worth planting at least two varieties, but you can successfully plant a single tree and expect to get fruit most years.
How big do avocado trees grow?
Left to their own devices’ trees can get to 15 metres tall. There are some claims of dwarfed avocados, but I have never seen a successful one. Avocado trees are not suitable to be grown in a pot. Tree size can be controlled with pruning.
When is the best time to plant?
This depends on where you are and what access you have to water. Firstly, avocados like to be planted into a warm soil, so in much of the country that would mean from October through until early autumn. If you still get frost in October, then delay until the possibility of one has passed. As soils dry out you will need to water/mulch to maintain a reasonable soil moisture. (DO NOT over water).
Should I prune my trees?
Avocados, like most trees like to be pruned. It helps maintain trees to the desired size and also helps them maintain youthful vigour. It’s important not to cut off all of next years flowering wood, so make one or two big cuts rather than many cuts right around the tree.
What fertiliser should I use?
With the oil content in the fruit being very high it takes a lot of nutrients to grow avocados. We recommend fertilising little and often with a high nitrogen fertiliser. Perhaps an application every six to eight weeks through spring and summer. Use a product with an NPK analysis of roughly 12-4-12. Animal manures can be quite effective as they release slowly, but ensure they are well composted otherwise root burning could be an issue.
Should I mulch my trees?
Mulch is great for avocados. Ensure it is well composted to avoid nitrogen draw down. Most organic material will work, but avoid materials like lawn clippings as this may suffocate trees. Ensure the mulch is not touching the trunks of young trees as this can cause stem rots. How long will it take for my trees to fruit? You can expect some fruit in year three. It is always a good idea to remove flowers in the first season so the tree can put all its energy into getting established. As the trees grows, the number of fruit will grow! How much water should I give my trees? Far more damage is done over watering than under watering. Water deeply, but no more than once a week. Should I stake my young trees? You need to avoid any root damage to your trees so a stake to avoid too much tree swaying is vital. Remember to check any stake ties that may strangle the trees as they grow.
Why should I buy a grafted tree from a nursery rather than growing my own tree from a seed at home?
Trees grown from an avocado seed and not grafted are true seedlings the genetics are unknown. It may take anything from 5 to 30 years for a true seedling tree to produce fruit. Grafted seedling trees combine rootstock material with productive fruiting wood which will give you a fruit bearing tree in a much shorter time frame.
Do I need to spray for pests and diseases?
The pests to worry about are those ones that feed on the leaves and therefore weaken the tree. The main ones are Six Spotted Mites and Fullers Rose Weevil. If you want your fruit to look great you will also need to control Leafroller Caterpillar and Thrip. Your garden centre will have options to control these pests. Avocado trees can also be damaged by cicadas laying their eggs in young branches. This can cause a split in the branch which may be surrounded by a white, powdery exudate. Very little can be done to prevent cicada damage and it will not harm the tree in the long term. However, it may cause the damaged branch to be weaker so it should be the first choice to prune off if it will not compromise the trees structure. Where can I buy a dwarf avocado tree? There is no such thing as a dwarf avocado tree (despite claims being made by some). Currently, pruning is the best technique we have to control vigour.
All of our varieties for garden centers are grafted onto a seedling rootstock. Clonal rootstocks are not available for the retail market or home gardeners.
Hass New Zealand and the world’s most common variety. The Hass avocado is a crocodile skinned, large fruit weighing 200-300 grams. It is high yielding, and ripe from September through until March. It turns purplish/black when ripe. Hass is an ‘A’ type flowerer.
Reed is a large fruit, the size of a softball and often weighing over 400 grams. It is high yielding and is ripe from December through until April. It remains green when ripe. Reed is an ‘A’ type flowerer.
Bacon is a medium sized fruit weighing 150-250 grams. It is high yielding and is ripe from July through until September. It remains green when ripe. Bacon is a ‘B’ type flowerer. This variety has good cold tolerance.
Fuerte is the original, high quality Californian avocado. It is a medium sized fruit weighing 150-250 grams. It is medium yielding and ripe from October through until March. It remains green when ripe. Fuerte is a ‘B’ type flowerer. This variety has good cold tolerance.