Avocado Trees

By Jutta Thoerner   UCCE Master Gardener

Please give me some tips on growing and harvesting avocados.

Mike P.  Cambria

Our coastal climate is ideal for avocado trees with low temperatures in the 30s and 40s and highs that seldom top 80. A sandy/loamy soil is preferred since avocados need a well-drained medium soil to discourage Phytophthora, a deadly root rot disease. Expect to wait 9-15 years for your first fruit if you plant from seed; 4-6 years if you plant a young tree.

A common question is whether one should grow at least two trees - one with “A” flowers and one with “B” flowers. This is not necessary. But when both an A and B type are planted, the male and female flowers on each tree will open at precisely the right time and improve both trees' fruit set.  It is reassuring to know that a single mature tree has a flower set that consists of up to 1 million flowers per year.  From those 1 million flowers, 100-200 will develop into an avocado fruit. That's 1 in 10,000 flowers developing into a fruit.

Ideal temperatures for fruit set is 65-75 degrees F. Often pea or walnut sized fruit will drop off the tree. This is normal and no cause for alarm. The tree is self-thinning and will only keep the fruit that it is able to bear. Sometimes smaller cuke size fruit will remain and they are okay to harvest.  A regular watering and fertilizing schedule will insure that most of the fruit grows to size.  

When to pick avocados: look for a change in color on the fruit. A dull, less shiny color, or brown specks are a good indicator that the fruit is mature. Pick a large fruit and allow it to ripen to softness on your kitchen counter. If it does not shrivel or get rubbery, and it has good flavor when you taste it, note the date for future harvest.  Now you can pick the fruit as you want to use it, allowing for 1-3 weeks ripening time off the tree.  Many avocadoes varietals can hang on the tree for up to 8 months (Hass, for example) making this particular tree a perfect space-saving storage system.