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Photo
The avocado tree on the right was photographed in March of 2009, which is
about 1.5 years after it was planted in October of 2007.
It is planted on the north side of a wall and the east side of a
large pine tree. The pine tree almost overhangs the avocado, so it gets morning sun and
afternoon shade.
This avocado tree is a variety named Winter Mexican, a Mexican x West Indian hybrid,
and was mail ordered from Florida.
It is doing really well so far and has almost doubled in size to 6 feet tall. It has flowered once but
has not set any fruit.
This plant has also tolerated 115 F. in the middle of summer without
problems, and there should be no worries of this variety being damaged in the winter
because it is reportedly hardy to 22 F. This avocado tree shows no signs of salt burn which is quite
amazing considering my experience with other avocado trees.
Previously, I attempted to grow two avocados trees from California
and they both died.
All the avocado trees available in local stores are from California.
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My first attempt, a Haas avocado tree, was planted in early
spring and died in the
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middle of summer, even though it was in full shade. The Haas shriveled
up like a piece of lettuce in the sun when temperatures went over 115 degrees Fahrenheit.
It just couldn't take the heat.
My second California avocado attempt was a variety called Zutano. It took the heat better than
the Haas and faired well in the winter even when temperatures went down to 26 F., which is very
unusual weather for the Phoenix metro area. However, the Zutano slowly racked up salt burn damage which eventually
finished it off. It lasted about 2.5 years, and didn't grow much if at all.
Florida avocado trees might do better here in Arizona than the California grown plants because
they are grown on more salt resistent rootstock such as Lula and Waldin, where as the
California variety rootstocks are more resistant to root rot, but salt sensitive.
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Overview
Avocado trees seem to be the gardening urban legend of
Phoenix. Supposedly there are large mature avocados somewhere in the Phoenix area, producing
bushels of wonderful fruit, and when the moon is full there are fairies and leprechauns playing in the
branches. Okay, I made that last part up, but I have yet to see a large avocado tree
growing and producing in the ground here. The above picture does show that there is hope
but the jury is still out as to whether this tree will at some point
produce delicious fruit.
The main problems with growing avocados in Phoenix is that they don't like the summer heat
or the salty soil and water. Winter cold does not seem to be a problem with the more hardy
varieties.
Heat Tolerance and Sun Exposure
Young avocado trees definitely need afternoon shade in the lower Sonoran Desert
and should be shielded from the sun with shade cloth in June, July, and August.
Being on the east side of a deciduous tree is an ideal spot because the tree
will get the protection it needs in the summer, but will get full sun in the winter.
As for heat tolerance by variety, I have found that Haas avocado trees cannot
take the summer heat here no matter how much shade they get while other varieties
fare better.
Cold Tolerance
The more cold tolerant Mexican avocado varieties are able to take temperatures
as low as citrus trees can. So, there is not much reason to be concerned about them
in developed areas of town. My Zutano tree survived temperatures as low as 26 F. without
a single damaged leaf, while many of the ficus trees in the neighborhood were killed.
I have no seen no evidence of frost damage on my Winter Mexican avocado tree and it
has been in the ground two full winters with no protection.
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Planting
Dig a hole at least twice the size of the rootball. At a minimum, make the
hole 2 feet in diameter and 1 foot deep.
Work in a 50/50 mix of compost to soil.
Be sure to mix the compost and soil
as thoroughly as possible. It also is a good idea to finish with the
hole an inch or two recessed so that a watering basin is formed.
Watering method
The biggest challenge for growing an avocado tree here is the salinity
of the soil and water. Basin irrigation
is the most effective watering method for pushing salt away from the trees
root ball.
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Watering frequency
Avocado trees do well on a grass watering schedule.
An occasional deep soak is beneficial if the trees leaves are showing signs of salt burn.
Deep soaking is done by turning the house on very low and letting it run at the base of
the tree for several hours. Deep soaking will help to wash salt to the edges of the area of
soaked soil. After deep soaking, one can often see a visible ring of salt.
Fertilizing and Growth Rate
Fertilizer can raise the salinity level of the soil, so chemical fertilizers should
be avoided. Alaska Fish Emulsion 5-1-1 works well if used in moderation. The
0-10-10 fish emulsion formulation seems to burn this plant so I don't use it.
Which is interesting, because I have other plants that the 0-10-10 works very well on.
Pests
Avocados have no significant pest problems in Arizona.
Links to more avocado information
Growing avocados at TAMU
Growing avocados at CRFG
Avocados at Wikipedia
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