An avocado tree in bloom. Those flowers have a gender-bending life.
Just when you think you’ve got all your fruit tree information down—along comes a new twist.
Avocado trees are divided into two camps by the kinds of flowers they have: A flowers and B flowers.
Does that sound like Thing 1 and Thing 2 from The Cat in the Hat? The avocado flowers act like cartoons too, with complicated openings and closings and sex changes.
Mother Nature had a field day with this one.
Many plants are hermaphrodites, with male and female sexual organs, but avocados are unique because their sexual organs don’t function at the same time. UC Davis calls the avocado flowers “remarkable”.
The sexual organs of avocado flowers are active at different times of day (dichogamy).
“A flowers” are female (receptive to pollen) in the morning and male (shedding pollen) in the afternoon.
“B flowers” are male (shedding pollen) in the morning and female (receptive to pollen) in the afternoon.
For the most part, avocado cultivars have only A flowers or only B flowers. Production is best with cross-pollination between two cultivars, one with A flowers and one with B flowers.
But the reality is, most cultivars of avocado seem to get better and better at producing fruits as they get older, another pollinator or not. If you live in a good avocado growing climate, there’s almost invariably another avocado tree in the neighborhood that will be your avocado tree’s buddy for many years.
Little Cado (has A flowers and B flowers)
Little Cado (has A flowers and B flowers)
Avocado flowers stick to their complex schedule of opening and closing as long as the daytime and nighttime temperatures are over 70F.
If the temperature drops to 60F during bloom time they may not reproduce at all.
A temperature of 65F, though, may confuse the flowers just enough that they gender bend and have both sets of sexual organs working simultaneously.
Little Cado is a dwarf avocado tree, maxing out at 8’-10’ tall, and is your best bet for container growing. Prune it to keep it smaller if you wish. This is the variety with both A and B flowers so you can get fruit with just one tree. You need to protect Little Cado when the temperatures drop to freezing or below.
Jump over here to find out which kinds of avocados will thrive in your area. Then choose a combo of A and B trees for your garden or farm.
Watch our Growing Avocados video to find out how to plant, prune and harvest these versatile trees.
Photo by Cayobo available under a Creative Commons License Attribution 2.0
Nov 23rd, 2013 at 6:55 pm
The Zutano says it’s sold out until August 2013. Since it’s already November 2013, is this a typo?
Charlotte from Peaceful Valley Says:
Dec 3rd, 2013 at 12:23 pm
Janet, Thanks for catching that! We meant 2014 and are changing that.
Jan 8th, 2014 at 10:38 am
I bought a Mexicola from Peaceful and wanted to find out if it was grafted or grown from seed. I heard if not grafted the tree will have NO fruit which defeats the purpose of my purchase.
Stephanie Brown Says:
Jan 15th, 2014 at 10:04 am
Hello Paul, yes all of our trees are grafted onto seedling rootstock, you should be able to see a little V-shaped scar on the trunk. Our avocados are intended for fruit production. An ungrafted avocado will bear fruit eventually, but it will take longer and the tree will not have known characteristics like a cloned (propagated by grafting) cultivar such as Mexicola or Hass does.
Feb 19th, 2015 at 10:58 am
Hi, i am helping my San Francisco neighbors with their backyard, and they have an old avo tree. Is there any way to tell if it has a or b flowers? to my knowledge it has not produced fruit. Thanks!
Suzanne at Peaceful Valley Says:
Feb 19th, 2015 at 11:32 am
Very difficult to tell whether or not it has A or B flowers. There are a couple of reasons why it does not produce fruit, either it does not have a pollinator or the temperatures are just too cold. If the temps drop below 60F during flowering, and if there are the appropriate pollinators, the tree will not make fruit.
Mar 8th, 2015 at 12:56 pm
If you’re referring to A and B types, they are different because of time of the day that they flower, but all of them are first female then male (synchronously protogynous dichogamy). It appears as if they are like you described because of many flowers opening at the same stage