Avocado Facts

Here are some quick avocado facts for the absolute beginner who knows nothing about where these wonderful fruits come from. This is a super crash course. Here we go.

There are three major races of avocado trees. West Indian, Guatemalan, and Mexican. There are also hybrids that are crosses between two of these races. The Hass is a hybrid of 85% Guatemalan descent and 15% Mexican. The Sharwil is a Mexican and Guatemalan cross that is grown mostly in Hawaii and is considered by many to be the best tasting commercially grown variety (but this is a very subjective thing!). The Queen is a West Indian and Guatemalan hybrid which is why it matures earlier and is HUGE.

The West Indian race grows in Brazil, Haiti, all the real tropical countries. They are less sensitive to salt so they do well in coastal areas, however they are the least cold sensitive so they don’t flower very well in the Californian climate. They flower really well in Florida where it’s very humid and hot. They only take 7 or 8 months to go from fruitlet to ready-to-pick. They generally have less oil and are watery than the Hass avocado we are all used to. They usually produce the largest fruit of all the races. The skin is usually medium in thickness and shiny.

The Guatemalan have a lot of oil and they taste buttery and declicious, but unfortunately they take a year and a half to go from fruitlet to ready-to-pick! They flower poorly in tropical climates but profusely in California. The Hass that we all know and love falls mostly into this category. They have thick, rough skins. The leaves of this tree are very toxic and should never be consumed!

The Mexican race are usually small, thin-skinned fruits. The most typical is Mexicola. It takes about 6-8 months on the tree. The skin is usually smooth and they have an anise flavor. The leaves are actually flavorful and used in Mexican cuisine. The Mexicans are the most cold tolerant. If you live in an area with a very cold winter, such as San Francisco or Phoenix, you need a Mexican.

Flower types: There are A flower and B flower type trees. Every avocado flower is the same. They open as a female one day, close, then open the next day as a male, close, then either die if they haven’t been pollinated or in 2 weeks you’ll see a little fruitlet poke out. The difference between the A and B type is this: The A type opens as female in the morning, then male the next afternoon. The B type opens as female in the afternoon, then male the next morning. This means that in the morning, the A type trees will have female flowers open and the B type will have male flowers open, and in the afternoon the A type trees will have other male flowers open and the B trees will have other female flowers open.

Avocado flowers are mostly cross-pollinated by honeybees but they are also self-pollinated by the wind.

Here is a table that should help you visualize these flowering periods:

First Day Second Day Any Given Day
Morning Afternoon Morning Afternoon Morning Afternoon
A Type Female Male Female Male
B Type Female Male Male Female

The flowering period mostly occurs over a 6 week period in Spring between late March and early May.

The two types of flowers behave with clocklike exactness only when the average temperature (night minimum and day maximum) is above about 70°F (21°C). As the temperature falls, the daily openings for the functionally male and female flowers become delayed and irregular such that a single tree may have flowers in both the female and male stages at the same time, which explains how large blocks of just one cultivar set heavy crops via self-pollination.

A mature avocado tree will likely have as much as a million flowers in bloom during a single spring bloom period but less than 0.1% of this total results in fruit that hold to maturity. Even so a yield of 200 8-oz fruit, or about 100 pounds per tree, results from approximately 0.02% fruit set.

Avocado trees have a tendency to alternate bear, alternating moderate to heavy crops one year with light crops the next year. Some varieties like the Fuerte are strongly alternate bearing while others like Gwen or Reed are not at all.

Just like with people, the children of an avocado tree have traits of both the mother and the father. When you grow a new tree from the pit of an avocado fruit from an avocado tree, that new tree will not produce the same fruit as the mother tree! The new tree is a cross between the mother tree and the father tree that pollinated it. So, for this reason, all avocado trees of a particular variety are produced via cloning.

Cloning an avocado tree is when you take a small terminal branch from the variety you want, such as Hass, cut off the leaves leaving a few buds (this is called a scion) and you graft that scion onto a baby seedling tree. A graft is when a diagonal slice is made in the bottom of the scion and the top of the seedling and the two are placed together and wrapped with stretchy grafting tape. In a few weeks the two trees heal together and soon the scion begins to grow and spout new branches from the buds. When this tree produces fruit, that fruit will taste exactly like the Hass fruit from the original tree. This is how we have ensured that Hass fruit from a tree that was originally planted in 1926 is still around and going strong (even though that tree died in 2002). There are now hundreds of Hass mother trees maintained at all the major nurseries. Any Hass tree can become a new mother once it gets large enough.

When an avocado tree is grown from seed it takes 5-7 years to produce fruit and you’ll never know what it tastes like until then! Cloned trees will produce fruit when 3-5 years old. So I think you’ll definitely want to plant a cloned tree.