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Avocados in the PNW

Avocados in the PNW

I know that avocados have been discussed many times on this message board. I've read on here as well as other places that there are at least a few avocados that are cold hardy in the pacific northwest and can even survive temperatures into the teens.

My question is whether there are any avocado varietals that will actually produce good edible fruit in the PNW. I'm also wondering which avocados require the least sunlight and heat and which ones do well in a container. Finally, I'm curious if there any avocados that are truly self-fertile or whether a branch from a tree with a A-type flower need to be grafted onto a tree with a B-type flower (or vice-versa)? Has anyone on here had success with fruiting avocados in the PNW? Thanks.

The following thread was started by Andrew on November 20, 2008 at 11:22 am PST

hardy avocados

my guess is that there are no truly "hardy" fruiting persea (p. americana ssp. americana or p. a. ssp. drymophylla) for growing outside year around---you might get away with them on the warmest parts of the southern oregon coast. other persea species including p. thunbergii (japan), p. podadenia (mexico), and several others from the south and japan and china but none of the others produce fruit the size or taste of what you are looking for.---though some are excellent garden trees.

The above followup was added by georgeinbandon,oregon on November 20, 2008 at 7:30 pm PST.

avocados north of the Bay Area

I agree that it is quite unlikely that there are reasonable prospects for producing palatable avocados much north of the SF Bay Area. There are too many obstacles:

1. The trees themselves are fairly tender and even the hardiest Mexican varieties are likely to be damaged at temperatures much below 22F. They must be grown in sun to produce, so planting them under a roof overhang is not likely to be successful.

2. They bloom in early spring before the frost window has closed in the PNW, so flowers would likely be killed here.

3. Pollen receptivity is typically low, and if plants bloom before bees are active, pollination will not occur at all.

4, Plants tend to abort developing fruit in climates where early summer temps are too cool.

5. Most importantly, the flavinoids in avocados are climate dependent. Even in northern California where fruit can generally be produced, it often isn't very good. The only reason to grow a fruit tree is to produce high quality palatable fruit.

There is a rumor of an avocado tree growing in Harbor, OR, but I have not seen it myself, nor have I heard of anyone claiming that it produces good fruit (if it exists at all).
The best prospect for growing an avocado here would be to get a dwarf variety like 'Holiday', 'Little 'cado' or 'Don Gillogy', grow it in a tub in the greenhouse and hand pollinate it. In most of the PNW, it could probably spend late May to late September outdoors.

The above followup was added by Steve in Brookings on November 21, 2008 at 11:39 am PST.

Mark (Seattle, z8)?

Mark, are you still out there? Any comments?


I will probably post a long comment tomorrow; but before I do, I sorta wanted to hear what others had / have to say...

The above followup was added by DavidInAmityOr,Z8 on November 21, 2008 at 1:36 pm PST.

Moorpark vs Bothel Ave Lo.jpg

Some background data...

My avocado grove was located in Moorpark, CA. So, that's where I am familiar growing avocados, and we might as well use it as the base for talking about growing and fruiting avocados there in Bothel, WA.

Your average low temp is pretty good. I'd say you are going to have to be careful with the lows in Dec-Jan-Feb-Mar... but more on that later...

The above followup was added by DavidInAmityOr,Z8 on November 21, 2008 at 9:23 pm PST.

Moorpark vs Bothel Ave Hi.jpg

And more background - average high temps compared... more later here too...

The above followup was added by DavidInAmityOr,Z8 on November 21, 2008 at 9:26 pm PST.

Some reference threads...

Here are some threads that I participated in, from oildest to most recent, discussing avocados on the main Cloudforest ("the Cafe")...

Some of this might be referenced in the following discussion...

A great thing about the internet - there is too much information, often confusing and conflicting! You have to decide who you believe in!! For me, I would pay particular attention to Jason's comments (Austrailia)and Ben's (New Zealand). With the exception of Ashok and Harvey C, I don't know, but the Calicentric model of the universe just doesn't quite hack it for me...

The above followup was added by DavidInAmityOr,Z8 on November 21, 2008 at 9:39 pm PST.

Jubea Chilensis north of the Alps...

So, let's start off with a palm, for all the palm people! The point being: don't believe all the nay-sayers. If you want to grow an avocado tree and get excellent fruit there in Bothel - you certainly can! In my opinion of course! It's merely a question of doing the right things and a certain amount of money...

This isn't my picture, here is the thread it is originally from:

The above followup was added by DavidInAmityOr,Z8 on November 21, 2008 at 9:44 pm PST.

The facts, just the facts...

So, OK, in my opinion, here are some avocado facts (not just California, but the world!):

Guatemalan types are native to cool, high-altitude tropics and are hardy 30 - 26° F.

Mexican types are native to dry subtropical plateaus and thrive in a Mediterranean climate. They are hardy 24 - 19° F.

Mature Guatemalan trees will tolerate temperatures as low as -4°C (25 F) for short periods without damage.

Trees can also tolerate temperatures as high as 40°C (104 F) for short periods. However, prolonged exposure to high temperatures results in severe stress and loss of productivity. Avocados like cool ocean breezes, average daily high temperatures for avocados should be less than 33°C (91 F).

Temperatures between 16 (61 F) and 24°C (75 F) are good for growing avocados.

Night temperatures of 5 (41 F) to 10°C (50 F) between Dec and Feb (northern hemisphere) stop shoot growth and promote good flowering.

Temperatures above 10°C (50 F) at night and between 20 (68 F) and 30°C (86 F) during the day are required at flowering.

Avocados are sensitive to saline irrigation water, water salinity should not exceed 0.6 deciSiemens per metre (dS/m)
with a chloride content less than 80 milligrams per litre (mg/L).

The optimum pH is 5.5-6.5.

The above followup was added by DavidInAmityOr,Z8 on November 21, 2008 at 9:54 pm PST.

Calicentric facts...

By far rhe largest share of the commercial crop in California is Hass (about 95% of the crop), Next is a relatively new varieity: Lamb Hass (maybe half the remaining total). The majority of Californai avocados are grown in San Diego (54%), followed by Ventura county, where my grove was (21%). Ventura (and Santa Barbera) are considered the "northern", colder commercial avocado growing area. I regularly had "frosts" that did considereable damage to my avocados. There were mostly Valencia orange groves around me - I can not recall them ever getting any damage at all. Most of my grove was Bacon, but I had maybe 35 trees that were top-worked to Hass, and one Pinkerton. The Hass were blasted back to 4" wood several times while I owned the grove, the Bacon never received that much damage...

The above followup was added by DavidInAmityOr,Z8 on November 21, 2008 at 10:03 pm PST.
A Seattle centric view of the world!

So, the first choice you have is Mexican or Guatemalean trees? I recommend Guatemalean. Why? I think you are going to want to have some sort of "enclosure" for the avocado; not only for winter lows but to warm up the climate in all months but the summer. In my opinion, it doesn't have to be fanncy, poly film over 2x4's would be just fine. This is what I plan to do; I'm also going to do some "root zone heating". Nothing fancy, maybe a couple of two gallon buckets sunk into the ground, each heated with an aquarium heater is along the lines I'm thinking. Maybe a set of Christmas lights for the branches.

So, if you are going to do this, it's merely a question of how many days you have to power the setup, and then winter cold becomes a total non-issue (in my opinion, of course). And greenhouses are very good heat traps, especially outside of our gloomy winter months (assuming Bothel is about the same gloominess as around here!), so I'm not really talking about powering the enclosure outside of the winter months (the before mentioned Dec-Jan-Feb-Mar months.

I see I still haven't really explained why my first choice is Guatemalean. The primary reason is taste - I myself have never had a good Mexican race avocado - even though I had hundreds of Bacons (a Mexican type)! Other reasons: Guatemalean types are adapted, amnd originally come from, high cool tropical climates. Mexican ones came from subtropical Mediterrean climates (ummm, like but not California). So, I think they will be better growers in the PNW...

Here is a picture that Mark (Seatle) posted a while back on the Cage, and the thread it was in. Pretty "cool", and exactly the sort of protection I am talking about! Good job, Mark!!

The above followup was added by DavidInAmityOr,Z8 on November 21, 2008 at 10:20 pm PST.

Opuntia ficus-indica in Seattle snow...

And here is Mark's cactus in the shelter with snow on top - pretty cool!

(Mark - I hope you aren't offended at me reposting your picures! Imitation is the sincerest forn of flattery, neh?!)

The above followup was added by DavidInAmityOr,Z8 on November 21, 2008 at 10:24 pm PST.

Avocado varietals...

My top choice is the Hass: a moderately vigorous spreading tree, and the top commercial cultivar (which I am sure some consider a big drawback, differences in opinions are OK with me). Avocado trees can get very very large, so my thought is that you want a vigorous one, but not too vigorous. If you read the threads I gave above, you saw that Jason keeps his Hass at about eight feet, and Ben says he has seen Hass trees kept at six feet.

My next choice is a Pinkerton: a spreading, shorter tree with excellent fruit (ah, in Ventura County! But why start with a tree that has inferior fruit, and expect it to have better fruit in a worse climate?). Basically the same reasons as the Hass: I know this tree can have good fruit, and is a lower growing more spreading tree. Much easier to make a "poor man's greenhouse" wider than taller!

Holiday (XX3) might also be a good choice, but I have never grown it so I can't say much about it. It is supposed to be a compact tree, but compact in the horizontal sense (I.e. low ground "footprint"), and have very good quality fruit. I am also wary of any tree that is touted as "slower growing", as I don't think that is particularly a good idea in a marginal climate.

And your last concern: pollination has a simple answer: you want a "type A" tree. See Jason's comments in the above mentioned thread. San Diego'ans need to worry about "type A" amd "type B", but we who live in colder climates don't. Type A's are essentially self fertile in cooler climates...

Oh, and lastly, I am also trying to find somebody who will ship me a tree on Toro Canyon rootstock - a cold hardy root rot resistant rootstock...

All for now - hope this helped!

The above followup was added by DavidInAmityOr,Z8 on November 21, 2008 at 10:45 pm PST.

Summer advantages

The interior valleys of Western Oregon, especially SW Oregon, definitely have the best summers for avocados, though parts of the Rogue Valley would definitely have too much spring and fall frost. And the southern Willamette Valley has spring/fall frost PLUS cool night lows in summer.

So I would say the best chance at an avocado venture in the PNW would be one of the warmer spots in the Umpqua Basin which has the trifecta of relatively warm nights, shorter frost seasons, and a fairly mild hardiness zone. Some parts of the basin have average January high temps. near 50F, which isn't exciting but it's better than 45.

And there is less rain in the Umpqua and it warms up more quickly in spring. You would have to avoid high hills and frost pockets, though. And even the best climates would still require a lot of protection and a good sunny spot for absorbing extra heat. It would still not be a simple task by any means. But that's where I think you would have the best chance at at least partial success.

The above followup was added by Eric, Eugene on November 21, 2008 at 10:45 pm PST.

Passive solar...

Uh oh - I forgot an important point! You need to give an avocado plant the maximum amount of sun you can. Twelve hours a day (anytime we have twelve hours a day, of course!) or better being the goal. I also think this is true for any fruiting sub-tropical: citrus, olive etc.

Also, my menory is getting shot. There are actually two fruits we grow, that we do not particularly grow because they are sweet (I mentioned olives in the thread a while back about growing citrus). As Stan pointed out (also a while back), avocados are one of the very rare fruits we eat that aren't sweet, instead their flavor is derived from oils. So, since I can sucessfully grow olives in a non-olive climate, why not avocados?

With a little added heat, of course. And it doesn't have to be active power - passive solar is good for increasing heat too (as is a southern exposure). See a picture of my rock pile - a nice little passive solar habitat. Too bad my wife wants to plant a palm there!

And remember:

"Temperatures between 16 (61 F) and 24°C (75 F) are good for growing avocados."

An unheated basement with a walk out sliding glass door will work just fine in winter for a young avocado too! In my opinion, of course!

The above followup was added by DavidInAmityOr,Z8 on November 22, 2008 at 8:45 am PST.

Olive harvest...

I just had to throw in a picture of some Frantoio olives I picked last weekend here in north west central Oregon. When I first planted olives, I was told (by the Agricultural Extension Service, etc) that: "Olives don't grow here".

"Food" for thought!

The above followup was added by DavidInAmityOr,Z8 on November 22, 2008 at 8:53 am PST.

Avocado Buds...

My Hass tree is still outdoors. A quote from Jason:

"Avocados flower when temps cool after summer. You will notice as soon as you have a couple of weeks of cool weather at the end of summer the next set of buds will be flower buds. It doesn't have to be very cold for this to happen and sometimes my Avocados are sending up flowers before Winter starts but once the real cold sets it they stop growing untill Spring."

So, I'm hoping that the fatter buds that have formed are flower buds!

The temperature here has barely kissed freezing so far (an of course the avocado is under a patio overhang). But, soon, I have to do something - what? Build a "poor man's greenhouse"? Bring it inside the un-heated basement? Bring it inside and put it under my T-5 florescents? Decisons, decisons!

Best regards!
David Lawrence

The above followup was added by DavidInAmityOr,Z8 on November 22, 2008 at 9:38 am PST.

Pinkerton agents

David came through again! I doubt that I have ever eaten a Mexican avocado but I'm taking David's word that they don't taste as good as Guatemalans. From what I gathered, Pinkertons are the most cold hardy Guatemalan type A avocados at about 30 degrees. Also, I like the fact that they produce a large fruit with a small seed. My only worry with the Pinkerton is that the Sunset Gardening Book says it is a "large tree" but I assume that as long as it is kept in a container and pruned, I'll be able to keep it to an appropriate size. 30 degrees is plenty cold hardy for me as my dwarf citrus trees are in the same range and will have to be in my soon to be constructed redneck greenhouse during the winter anyway. I'll put up pictures in the next week after I build the thing (and before my homeowners association complains and makes me take it down).

The above followup was added by Andrew on November 22, 2008 at 7:04 pm PST.

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