Would love to hear another update on that one @MockY! Duke seedlings have proven fairly vigorous and hardy for me, even those planted out after only one year from seed. This seedling of Duke was less than one year from germination when it had its first hard freeze last fall, and survived a winter low of 17°F, but re-grew from well above ground and is already at least as big as it was at the end of last season:
You can see more photos here (it may take a moment or two to load them all), including photos taken right after the worst freeze events and before spring growth started this year.
It did have slight protection for the worst couple freezes (an upside down flower pot, no heat source). I’m hoping with an El Niño winter this year, we can avoid any freeze damage so it can size up even better next year. I’ve also planted and distributed other seed siblings that were kept in the greenhouse this last winter, so there may be others that are hardier but so far that’s the best.
Hi@swincher, could you please share the source of duke seeds. Has it fruited for you?
I have tried so many including supposedly cold hardy varieties, but they all die when we have a few freezing days in Gulf Coast area.
@BBF
Duke and Lula seeds will not grow Duke or Lula rootstock. Lula is a Hass-grade Avocado sold in supermarkets. Sometimes the sticker number on avocados indicates the actual cultivar – but you’ll have to look up the number.
Lula is a green-skinned cultivar mostly grown in Florida, both for fruit and for seeds to use as seedling rootstock for the retail nursery trade. It’s popular as a rootstock because its seedlings tend to have good tolerance for the alkaline soils there, but the fruit is highly susceptible to scab. Here’s a photo of what they look like when they aren’t scabby, I’m not sure this could pass for Hass:
I think a big part of the problem is all the nurseries there pretty much exclusively use Lula seedlings as rootstock. I have never had a Lula seedling rootstock survive the winter, even below ground, and even 4+ year-old trees, but nearly every pure Mexican-race seedling I’ve grown has at least survived below ground and regrown from the roots the next year, even with 6+ days below freezing 24/7 and lows in the 16-17°F range. Nevertheless, every retail and wholesale propagation nursery in FL uses Lula seedlings, and most Gulf Coast nurseries source their avocados from those places. I called over a dozen nurseries offering “cold-hardy” avocados from south FL to the panhandle, 100% of them said that’s the rootstock they use, and the reason they gave was that it didn’t matter how hardy the rootstock is. Which I can clearly debunk. But their way sells more trees I guess!
Hi @swincher, could you please share the source of duke seeds. Has it fruited for you?
I got my Duke seeds from Marta, she sometimes sells a few if she has extras, but mostly she uses them as rootstocks herself. My 2nd year Duke grafts flowered nicely in my greenhouse this spring but they didn’t hold any fruit. They have grown a lot since then, so I’m hoping they will start bearing next year, along with a half-dozen other cultivars that are big enough to hold a few fruit at least. I’m not just using them as rootstocks though because the project I’m organizing is primarily trying to find seedlings of hardy cultivars that are even hardier than their parents, which mostly cannot survive here without significant dieback. So once my greenhouse starts producing seeds, I’ll be distributing (for free) the seedlings locally here in the PNW to members of our project.
The seedlings of Duke are remarkably uniform, with vigorous growth but tight internodes. I can see why so many of its seedlings have been selected to be clonally propagated. I think most people would find most Duke seedlings to be just as satisfactory of a rootstock as those UC selections.
To give an example of what I mean, here was the “seedling class” of last year in October, with the Duke seedlings circled:
They look almost like clones! Far less variation than among the seedlings of other cultivars. For those curious about the other seedlings, here was the original caption when I first posted that photo:
Thank you @swincher for sharing the information. Reading your posts make me think there is still hope and I need to try one more time to grow some of the suggested cold hardy varieties again. I will focus on Mexican, Duke and arivappa this time.
I think you have a much better chance of success there in 9a along the Gulf than I do here, especially if you can protect it until it’s been in the ground for a couple years, but you probably will still get significant winter dieback any year you get into the teens.
If you ever are over in the Gainesville (FL) area I can put you in touch with a couple different guys who use seedlings of their local trees (Del Rio, May, Gainesville, etc) as rootstocks, but they don’t ship trees.
By contrast, this Duke seedling (grafted with “Del Rio” on the left side) was kept in the greenhouse for the coldest part of winter, and will stay in this 15 gal pot until next spring, when it’ll go in the ground:
@swincher Thanks for reminding me. An update is certainly overdue.
The tree is mature enough to flower (born February 2019), and it does so very profusely. The tree is absolutely covered in flowers. Last year was the first time it did so, but a late frost killed them all. However, the tree itself didn’t seem effected at all except for maybe a few leaves with brown “burn” marks.
This year we had no such misfortune, but despite plenty of pollinators and tons of flowers and no frost, no fruit set at all. I’m far from an avocado expert, but it sure seems like the tree needs another tree to cross pollinate with. I don’t know what else it could be, unless this is the nature of growing it from seed and some genetics misfired or a female/male kind of thing. So if someone could share possible reasons, I’d appreciate it.
With no further ado, here’s a picture of how it looks today. I’d estimate it being around 13-14 feet tall. I feel like I need to prune a little to balance the tree out. Not sure why it started to grow the way it did as it was very uniform the first couple of years. I have not fed it in a long while, so I’ll do that later today.
Even in a large, mature tree with a nearby compatible pollenizer, only a few hundred fruit usually are held to maturity despite well over a million individual flowers. Something like 1 out of 10,000 flowers. Smaller trees do sometimes have higher fruit set, but not hugely so.
For your tree it was probably only a few thousand or maybe tens of thousands of flowers, and they probably opened and closed in pretty good synchronization, meaning none of the flowers were receptive to pollen (female) at the same time that other flowers were shedding pollen (male).
You could either plant or graft onto it a compatible variety with the opposite flowering pattern, or manually collect pollen when the flowers are in male phase, and hand pollinate later that day or early the next day when all the new flowers open in female phase. The problem is there’s too much time between those phases, so none of the pollinators still have the pollen on them at the right time.
When your tree gets much larger, it will probably become a continuous cloud of pollen even 12 hours after the male -phase flowers close up shop, so I bet you’ll see fruit setting then.
This is really interesting re: Lula’s lack of cold hardiness.
I know the guy who has the Millennial Gardener channel on Youtube has a four or five year old Lula he’s been growing in ground over in Wilmington NC. I know he uses a lot of winter protection, but he must be doing way more than I thought if he’s kept it alive so far.
It has been continuously flushing so far since it started in the spring, no sign of periodic flushes like most other avocados. Looks like it’s about to get bushy again at the top, I love to see this because I think the bushiness is a big part of what protected the base:
Where are you located @CherryLover1? This isn’t a good time of year for grafting in most locations, unless you’ll be keeping them indoors all winter. I’ve had some success bench grafting avocados in late summer and keeping them in a heated greenhouse, but usually the early spring grafts catch up with them the next year anyhow.
I have plenty of spare Duke scions, could probably spare one scion of Aravaipa, but if you’re in CA then probably are limited to sources within CA due to the state’s rules regarding import of avocado plant material. Feel free to PM me rather than discussing here in thread.
I am in So. California, darn. I guess I have to wait for someone in California. Thank you for kindness though. I am planning to graft in next year Spring, so I don’t need them right now. I have some rootsotcks growing.
