Given that a tree is healthy and making lots of flowers, there are three main external conditions that create ideal avocado pollination potential: warm weather, lots of bees, and different varieties blooming near each other.
While I’ve seen these elements work together for good avocado fruitset in my yard and elsewhere, below I note snippets of more robust evidence from others. Click the reference links for the full stories.
Warm weather
High mean temperature (average of daily high and nightly low): “Ordinarily, the higher the temperature mean, the more favorable the set prognosis. This explains why most of our set is usually toward the end of the blooming period.” Bob Bergh in 1967
How high? “Daily means above 60° are necessary before much fruit will set; and means above 65° give the best fruit set.” Len Francis in 1974
B types need it warmer than A types: Shepherd (B) needs five degrees F higher than Hass (A) for “potentially favourable fruit-set.” Birdie Carr of Australia in 2019
What to do? “We have no control over the weather!” you say. True, but by growing the most suitable varieties for our location we can achieve results as if we had some control. For example, since B type avocado varieties require warmer weather than A types, if you live right on the beach where spring days don’t warm up or at the bottom of an inland valley where spring nights dip down low you can grow an A instead of a B to increase your pollination chances.
Lots of bees
Need for bees: “The evidence from our caging experiments indicates the following. Practically every avocado fruit set means that a honey bee transferred pollen to that flower, from some other flower.” Bob Bergh in 1967
More bees the better: ” . . . an average count of 40 bees per medium size tree is a good number.” This is research from Gad Ish-Am as presented by Reuben Hofshi.
Not only honeybees: Other effective pollinators observed include bumblebees, numerous species of stingless bees, and even wasps and flies. Pollinators of Avocado by Ish-Am et al.
What to do? To bring in more bees you can install a bee hive or simply provide food for them, as I explain how I’ve done in my post, “Growing a Bee Garden”
Different varieties together
Different varieties: “The data from the various groves observed show that trees of a given variety frequently set more fruit when located proximate to a second variety than when located farther removed from the other variety.” Bob Bergh in 1964
Varieties of different flower types even better: “Interplanting an A and a B variety, provided that their blooming season overlaps adequately, thus provides maximum opportunity for cross-pollination. We have thereby obtained yield increases up to 150% in individual years, with 50% increases frequent.” Bob Bergh in 1967
Closer together the better: “Close watching showed that bees have a strong preference for sticking to one avocado tree at a time . . . But as can be observed bees do cross freely when the foliage of two varieties interlace, with no open space between.” Orange Clark in 1922
What to do? Plant a companion for your avocado tree. For example, Bacon is a good companion for GEM, as shown in this grove. Or if space is at a premium, then you can plant two trees in one hole (see examples of this in my post, “How far apart to plant avocado trees”) or graft in a pollenizer branch (see my post, “Grafting a pollenizer branch into your fruit tree”). For a list of the flower types of avocado varieties, see this one from the Orange County chapter of the California Rare Fruit Growers. But do keep in mind that most avocado varieties will produce plenty of fruit in most years even if provided no cross-pollination opportunity.
Here’s a two-minute video version of the ideas in this post, showing trees in my yard:
Having warm weather during bloom, seeing lots of bees visiting female flowers, and different varieties of avocado trees growing near each other don’t guarantee fruit. And cooler weather, few bees, and a lone avocado tree can still end up with a decent crop. But the presence of these three ingredients is almost always correlated with higher pollination and fruitset in avocado trees.
Interested in learning more about avocado pollination? Check out these papers, including their references:
“The Avocado Flower and the Pollination-Fruitset Process: Ideas from a California Perspective” by Mary Lu Arpaia and Reuben Hofshi
“Finding the Best Polliniser for ‘Hass’ Avocado and the Effect of Honeybees as Pollinators” by Bezuidenhout et al.
All of my Yard Posts are listed HERE
Another great blog. Just yesterday in Poway HD, no avos, and a few weeks ago El Cajon and Santee basically none, just a few at Lowes. Last month at Walter Anderson only a few varities, picked up a #5 Sir Prize @ $70!!!…., due to pandemic? Feel for those trying to start out and find varities. Thx again for the great info. I’m at 17 trees with 17 varities, doubles of Reed, Pinkerton, multi grafted Fuerte–Ettinger, Sharwil, and Lamb…wanting better production on it. Plus grafting is FUN.
Hi Frank,
Thanks for the reports. That’s tough that avocado stock is so low everywhere. I was at Subtropica in Fallbrook yesterday and they don’t have as many varieties at the moment as they usually do, but they still have many trees. And the prices are certainly less than $70 — yikes! I don’t know the history of your Sir-Prize, but I do know that what happens at many retail nurseries is that they buy small trees in sleeves from a wholesale nursery like Subtropica or Brokaw and then grow them bigger for a while, pot them up, and sell them to home growers at a significant markup. There’s nothing wrong with this practice. That’s just the routine.
You have so many varieties that you’re going to supply a farmstand year-round with avocados someday soon!
The reports on avocado pollination was very interesting. This is my 1st year to have avocado flowers. My two plants are in 20 gal pots;Poncho & Fantastic. Located 20 miles S of Austin, Texas where we experienced the 8 inch snowfall Feb 14 2021. Both trees were planted in Feb 2020 from nursery grafted stock. Snow lasted 2 weeks but trees were in heated garage, but delayed opening until late March due to cold windy weather. Fantastic had more flowers than Poncho! Finally Fantastic flowers started opening but nearly all local bees had been killed from the 4F degree low temp. I did notice a few flies 1/2 size of house flies on flowers and a few yellow jacket wasps working them. Then April 1st I saw the first fruit develop. Fantastic flowers were slow to open up and over 1/2 had fallen off. Poncho flowers never did open fully and set no fruit despite being beside Fantastic tree! Largest 8 fruit are now, May 15, thumb size with a few more pinto bean size. A few dropped but I hand thinned about 20 more. Some new growth started after applying AmSo4 and 10-10-10 +2% iron in rain water. We are having colder, windier weather than normal but less rainfall. Comments anyone? Tom Longbrake Kyle Texas.
Very interesting, Tom. Do you know the flower types (A/B) of Fantastic and Poncho? I’m wondering if Fantastic is an A and Poncho is a B.
Anyway, great to hear of your crop on the Fantastic.
I probably see more flies and other bugs on my trees than bees. I think they all contribute in some way. All of my trees are pretty immature and flower at funny times so who knows what’s happening. I’ll settle for one ripe avocado this winter and will consider that a success.
Greg, I have followed your advice on my tree planting with a Fuerte, Lamb and Hass. The Fuerte took several years to kick in, but this year it has fruited up beautifully along with a potential bumper crop of young fruit on the Hass. Planting them in close proximity to each other and attracting pollinators has done the trick. Thanks for the direction and all of your posts.
I do have two Q’s for you. Is it too late to graft scions to my seedling rootstocks or wait until early next spring? (Rootstock is unknown since the seeds were from store bought Hass.) I have come across an old tree in Whittier that the owner of the property said was huge when they bought the home in 1986. She gave me a bag of ‘cados that look like Fuerte and taste absolutely outstanding (better than the best Hass hands down), but why I want to get scion wood from that tree is because the fruit is not oxidizing after being cut. Even the guacamole is staying perfectly green after four days. WTH is this? Have you heard of that other than a Sir Prize? TIA
Well, I found your posts on grafting and “Propagating Avocados”, so if I can get budding wood from the old tree I’ll give it a try.
But, what about the non-oxidizing avocado? This is a first for me.
Hi Arthur,
Thanks for writing. You can graft avocados successfully any day of the year, but it’s far easier around late winter in Southern California. March is generally my favorite month, the month when I get the most take.
What nice feature that that avocado has of not browning. I have encountered some others that stay green like that one and Sir-Prize. Edranol is one that comes to mind that I’ve been eating recently.
I am just picked up two B type trees (Reed & Pinkerton) to partner with my decades old Fuerte. I have a tight but workable spot closest to the Fuerte such that canopies intersect. The other spot has more elbow room. Which would you recommend I plant in the tighter spot, the Reed or the Pinkerton? I am planning to limit height there to 12-15 feet.
Edit: two A type.
In addition to my Fuerte in the back yard, I have a Catalina (A type, I believe, popular in Florida & Cuba) in the front. I grew this from a seed. At the 5 year mark, it produced two large fruit which, in my judgment, were very close to true to original. However, last year I had no blooms. This year, it had plenty of blooms, none of which connected. It is a lushious tree, super large by now (had to top it off twice by now), so I’m suspecting a pollination problem. The nearest avocado tree is a Hass across the street. I’ve been trying to graft it with Fuerte B for next season, but so far all the grafts have failed. When should I try grafting next? I live about 15 miles southeast of Downtown LA.
Hi Greg,
I’ve been enjoying your posts for a few years now and finally have a question for you. I have an established hass tree about 12’ tall and 10’ wide, and was wondering if I could graft on a Zutano branch, mainly for pollination benefits. My thought is that the opposite flowering pattern of the trees would benefit each other.
What do you think?
Hi Chris,
Good to finally hear from you! Yes, you can do this. I have done it. However, to be most successful you should try to graft to a vigorous branch that is in a sunny part of the tree, and do not graft too low to the ground nor too far at the very outside of the canopy. This might sound difficult to follow or even understand, I know. I should do a video on this.
Here’s what can go wrong. You graft to a weak branch that is growing in a shady part of the tree and the tree just sheds that branch in the next year or two. You graft too low to the ground and the branch soon gets too shaded by upper branches and doesn’t flower much and is likely shed in the next couple years. You graft onto the outside of the canopy and the branch just doesn’t have enough space to grow much (and therefore flower much).
So, the best success I’ve had with these types of grafts is on the south or west sides of the tree, somewhat inside the canopy and then after the graft takes you prune some of the surrounding branches so the grafted branch gets plenty of sun, and definitely graft onto a fast growing branch (which is usually light green not gray, mottled, or brown).
Finally, don’t ever let your grafted branch hold fruit. After it flowers and does its pollen donation work, strip off any fruit that forms. This way it is most likely to flower again the following year.
See a bit more about this in this post: https://gregalder.com/yardposts/grafting-a-pollenizer-branch-into-your-fruit-tree/
I have been wanting to ask you a question on benching a 45 degree rock and clay hill for avocado tree. The cut is four feet deep. I built a box with pressure treated 2×6” and 4×4” wood to hold back soil. What should I put in the box sand? Then peat moss? Then top soil? The soil that was benched out of the hill slid down the hill and would be difficult to retrieve and mix in with the sand. I’m sorry that I am asking in the grafting section of your website.
Thank you, Miguel
Hi Greg,
How may I submit a check to you to order the 2022 Avocado Calendar? Although a member of both SD + North County Chapters, I’ll be Back East from 10/20-29, so I won’t see you at Vista meeting.
Thanks in advance
Steve Szost
Hi Steve,
Thanks for asking. Sorry to miss you at the upcoming meeting. I’ll send you an email.
Im in El Cajon and I have a pinkerton avocado tree that is developing flower buds in October. It also bloomed this spring and set some fruit that it is carrying now. Is this normal? Should I pinch these buds or will they produce viable fruit.
Hi John,
Pinkerton often starts blooming in October in certain locations. Sometimes this early bloom sets fruit but usually it’s the spring bloom that sets the most fruit. No need to remove the flowers; if they set, you’ll have some early Pinkerton fruit to eat next year.
Thanks Greg! Do you think my spring bloom will be affected by the shoots developing flowers now? Looks like over half the tree is developing buds right now and I’d be disappointed to only have half the flowers come springtime.
Hi John,
The amount of flowers and fruitset now will probably reduce the amount of flowers and fruitset in spring.
I know that’s what has been observed on other varieties that commonly have early or “off” bloom. For example, with the variety Carmen (a natural mutation of Hass), the overall yearly yield is about the same as Hass but it comes from fruitset in two clusters — a fall bloom and a spring bloom.
In other words, I don’t think you need to worry that your overall yield for the year will suffer due to some of the flowers and fruit being set here in the fall.
And as regards Pinkerton specifically, it is a highly productive variety. I know many Pinkerton trees that suffer from overproduction. They get sunburned branches and fruit because of the weight of the crop load exposing bark and fruit.
Hi Greg, I just found your site searching for “when to pick Reed Avocados”. After reading your posts, comments and replies for an hour (thank you very much), I have a question of my own. My small avocado/citrus grove (1 acre) in Elfin Forest is experiencing some problems. 4 or 5 of the mature Hass look sick. They are losing leaves and generally just look bad. Can you recommend someone who can come out to my property to diagnose and suggest solutions to my issues?
Thank you,
TV
Hi Todd,
Sorry to gobble up an hour of your time! I’ll email you.
This would make a great YouTube video: “The avocado doctor is in.” I’d love to know what happens with any inspection— what the diagnosis is and how you recommend treating itt.
This seemed like the best place to ask the second question. But first, I used to be able to access categories of posts at the top of the page (maybe the three horizontal bars) but that no longer works. Am I the only one missing that? It doesn’t work on this notebook, my wife’s PC or my phone.
Anyway, today (the day before the first real rain of 2022 in Santa Barbara) I was sitting in my yard near my Hass avocado tree, and I say a hummingbird going after the flowers off and on for a couple minutes. Nearby is a naval orange that is pretty done blooming, I didn’t notice if the hummingbird visited there or not. I thought it was unusual to see a hummingbird on avocado flowers, as I didn’t imagine there’s nectar (or much anyway) in there. I suppose if the hummingbird managed to pick up pollen from a male flower on its smooth beak and deposit it on a female flower then pollination would happen. Seems sort of unlikely though.
I have Fuerte, Bacon and Pinkerton in flower but they do not produce any pollen. I’m pollinating with a blush brush but cannot gather any pollen. I live in Cape Town. There are very few bees,
Hi Phil,
In order to get pollen from the flowers your timing has to be precise. First, the flowers must be open in their male phase. For B types (Fuerte and Bacon), this will happen in the first half of the day. For A types (Pinkerton), this will happen in the second half of the day. This assumes normal spring weather. If it’s chilly, then all is delayed. If it’s hot, then all happens earlier and the flowers close more quickly.
Second, the male-phase flowers need to be releasing pollen, which doesn’t usually happen as soon as they open. Pollen starts to be released maybe an hour after the flowers open in their male phase, depending on variety and weather and other factors. You’ll be able to rub the male parts of the flower (anthers) and see yellow specks of pollen on your finger tip if the pollen is being released.
Have you seen this post? It might help: https://gregalder.com/yardposts/hand-pollinating-avocados/
By the way, those three varieties cross-pollinate very well here in California. That’s an excellent combination. In fact, I know a yard that has those three varieties and only those three, and the trees always have some fruit. In some years they are laden, especially the Pinkerton.
I will follow your advice to the last letter. I suspect temperatures play a big part, I tend to hand pollinate anytime of the day. Avo flowers are something else.
Phil