FYI--there is an avocado that will grow in zone 8/9 without protection! I got a scion from Dr. Manners from a variety named Mrs. Holland that was suppose to be cold hard--it got a good test last winter--at least 4 cold spells below 23/24 F--with no protection. It came thru with no damage at all--and this is a very vigorous grower as well--over 10 ft in just 3 yr from a simple bud graft!

I'd like to have some bud wood of that for testing in Arizona..
If you know where I can locate some please let me know..

The rootstocks have done very well so far, even in some high salt test plots, the fruitwood part is another issue, I have the ways to deal with our intense heats for many types of fruits, but we still have to deal with these once in 3 or 7 year cold snaps that drop to the teens with 5% humidity. A cold hardy AVO would be a helpful test..

I can send you some cuttings--paying it forward. Dr Manners told me that grafting seems to work best in the fall when it starts to cool. I tried the first time in Nov--when they do it in So FL, but they didn't work. The next yr I got him to send them to me a little earlier--in early Oct. That yr I had over 2/3 take. We get colder here a little earlier--I think Nov was too late--the plants had already stopped for the yr, but Oct left a little time for the scion to bond.

So let me know when you think you have about a month before dormancy.

I personally have had much greater success grafting avocados in the spring. The plants are not pushing enough it seems in the fall. Not only that, but any new growth on the graft in the fall, will be much more cold sensitive when it doesn't have time to grow more before you get a freeze.
Kern

Hi Skeet,

Where will I find the rootstock to bud on? I don't recall every seeing Avocado for sell so do I need to start some from seed. I think I recall that is what you did. I'm guessing that the Florida Avocado is the one to use or would the Mexican or California be better. I can get the Mexican one from the flea market here occasionally.

Yes, use seedlings that you grow from a pit. You can graft them 5-8 weeks after germination, while the stem is still very soft and herbaceous (and usually pink in color). Florida fruit with big pits tend to give a thicker rootstock (easier to graft when very young), but a Mexican race type will be more cold-hardy.

Unlike in citrus, where the rootstock affects the cold-hardiness of the scion, that is NOT the case in avocado -- your scion will have the same hardiness no matter what it's grafted to; rather, the problem here is that if you have a hardy scion on a tender stock, the stock may freeze out from under it, and the tree dies anyway. If you mulch well above the union before a freeze, that can solve that problem, most of the time.

Thanks Dr. Manners,

I'll be at the flea market tomorrow and will try to get some Mexican. Hope fully I can germinate both types and see what happens.

Questions:

Is it known if the original Mrs. Holland was a grafted tree or grew from a seedling?

To gain the most cold hardiness would it be better to root a cutting from the Mrs. Holland tree?

How cold hardy is the Mexican type?

I did not think about the freezing of the rootstock as the cause of the death of my other grafts--they had not grown nearly as much as the Mrs Holland.

I have been planting all my seeds directly in the ground--they sprout and grow fast--some faster than others, but the last two winter have killed most of them before I could graft them.

I have not tried rooting a cutting of Mrs Holland, but I would think that would work.

The original 'Mrs. Holland,' in Dallas, was a seedling. All other known plants of it are grafted. It appears to be pure Mexican race, so cuttings are a possibility (they are generally impossible with West Indian race and very difficult to impossible with Guatemalan race, but sometimes feasible with Mexican race). Still, likely difficult.

Certainly, the original tree in Dallas survived when the official temperature went down near zero F., but of course, that does not take into account microclimate. It may have been warmer on the actual site of that tree. Likewise, I've seen the original 'Gainesville' tree on the UF campus survive officially 6°F, with a lot of limb damage, but again, who knows the actual temperature reached by the tree itself.

Skeeter,

Can we try rooting some?

Unless other rootstocks are more cold hardy, then a rooted cutting would come as close to the original tree as possible. Right?

Dr. Manners,

No Mexican Avocados at the market this week. They had California ones. She said she would see if Mexicans were available for next week. I will get the Mexicans as soon as I can so we can do some comparisons.

Excuse my ignorance but what differences can we expect from a rooted cutting from Mrs. Holland vs a seedling from Mrs. Holland?

Maybe we should wait till we get a fruit from Skeeter's tree.

Darkman -- I think there may be a misunderstanding here -- a "Mexican" avocado is not necessarily from Mexico, nor are all the avocados we import from Mexico actually "Mexican!" What we mean by "Mexican" is the Mexican race of avocado, the subspecies Persea americana drymifolia, which has anise-scented leaves, generally small fruit, and the fruit has a smooth, shiny skin as thin as that of a tomato. For Comparison, West Indian race (Persea americana americana) has larger fruit, a slightly thicker, leathery peel, and no particular scent to a crushed leaf. The Guatemalan race (Persea americana nubigena) has medium- to large-size fruit with a much thicker, pebbly-rough peel, and again, no leaf scent. Most Florida types are pure West Indian (ripe summer through early fall) or WI x Guatemalan hybrids (fall and winter varieties). Most California varieties are Guatemalan x Mexican hybrids (e.g., Fuerte, Hass), or a few pure Mexicans.

So the source of your seeds is really irrelevant; it's the genetic race of the fruit that is important.

As for your other question -- cutting vs. seedling. A cutting of 'Mrs. Holland' will still be 'Mrs. Holland', just like a grafted plant, so its growth habits will be identical, and the fruit will be identical to the original. On the other hand, a seedling will NOT be true-to-type in avocados, and may vary quite a lot in growth habit, bearing, fruit quality, size, color, flavor, etc. Seedlings are best used as rootstocks for grafting, rather than being grown to maturity in their own right. Yes, there is a small possibility that a seedling would be really superior, but the odds may be 1 in a 1000 or even less, that it would be as good as our current, named varieties.

The last 3 avocados from my tree have fallen--we have eaten one--some critter got one and I have the last one on the counter.

The taste was not bad--but they do have a thin skin--you have to peel them with a knife.

Dr Manners, when would be the best time of yr to try to root a cutting?

I recently planted several more pits where I cut down some popcorn trees--one of them was a Mrs Holland pit.

Skeeter, Having never successfully rooted an avocado cutting, I really don't know when the best time is. Nor is there any known record of anyone rooting a 'Mrs. Holland', ever. So it may be one of the varieties that cannot be done that way. But who knows? Perhaps no one has ever tried it.

Malcolm