Author Topic: "Breeding" cold hardy avocadoes from supermarket seeds?  (Read 3245 times)

drymifolia

  • Sr. Member
  • ****
  • Posts: 459
    • Seattle 9a/sunset zone 5
    • View Profile
    • the drymifolia collective
Re: "Breeding" cold hardy avocadoes from supermarket seeds?
« Reply #50 on: December 17, 2022, 04:25:53 PM »
Yes, with significant protection I'm sure avocados can be successfully grown in some marginal climates, but here in the PNW  we have a very cool version of 8b. Even in mild winters the high temperatures rarely ever go above 10C, and often there will be a month or two where the low is around freezing every night and the high temperature is below 4-5C most days. Avocados seem to become weakened by this extended cool/cold, and more easily killed when there are cold events down to -5C or below. It also rains continuously, so any locations with poor soil drainage are prone to root rot.

I have been intentionally pushing harder on my seedlings than necessary, giving them little or no protection once they are planted outside, because I want to figure out which cultivars produce the hardiest seedlings. Once I've determined which cultivars to focus on, future seedlings will be babied a little more.

But the other people who I know that tried to grow grafted hardy cultivars here, and failed, had them die even with significant protection. I suspect they were on less hardy rootstocks, though.
« Last Edit: December 17, 2022, 04:30:55 PM by drymifolia »

Galatians522

  • Hero Member
  • *****
  • Posts: 1659
    • Florida 9b
    • View Profile
Re: "Breeding" cold hardy avocadoes from supermarket seeds?
« Reply #51 on: December 17, 2022, 09:16:18 PM »
Root rot is a huge problem with Avocado. Having soggy roots when the tree is forced into dormancy due to low temps is a recipe for disaster. That may account for the difference between a tree that is zone 8b hardy in Florida/Georgia but not in Washington state.

drymifolia

  • Sr. Member
  • ****
  • Posts: 459
    • Seattle 9a/sunset zone 5
    • View Profile
    • the drymifolia collective
Re: "Breeding" cold hardy avocadoes from supermarket seeds?
« Reply #52 on: December 17, 2022, 10:59:06 PM »
Root rot is a huge problem with Avocado. Having soggy roots when the tree is forced into dormancy due to low temps is a recipe for disaster. That may account for the difference between a tree that is zone 8b hardy in Florida/Georgia but not in Washington state.

Interestingly I've never had much of a problem with root rot for the trees in the ground, but my yard's soil has excellent drainage (high sand/silt content). The avocados in containers have had root rot issues, though, so mostly I bring them in the greenhouse after the rains start even when the temperatures aren't too cold.

I think the biggest difference vs 8b in the SE in terms of winter survival is the much colder highs. In 8b Florida you frequently have winter days in the 60s or 70s (F) and just get cold fronts once in awhile with brief freezing temperatures. In 8b WA, the high might not go above 45F for two straight months, and may not even go above 40F for weeks on end. In our cold snaps the highs will be below freezing for days in a row, with lows in the teens or low 20s for multiple days in a row. Those multi-day freezes are what usually kill the trees above ground, even if the roots survive.

lajos93

  • Member
  • ***
  • Posts: 67
    • Hungary, Zone 7 (Zone 9a GH)
    • View Profile
Re: "Breeding" cold hardy avocadoes from supermarket seeds?
« Reply #53 on: December 18, 2022, 01:58:37 PM »
Im thinking about starting a few seeds and passively covering them with a portable plastic greenhouse sheet ,maybe a water barrel inside to guarantee the above freezing temps even on colder days

Im in zone 7 but we dont really have less than -8c on an average winter. I still need the hardy ones to survive but at least if i only have to keep them above -6c then its doable with water barrels i thnk
stuff

850FL

  • Sr. Member
  • ****
  • Posts: 484
    • zone 8b/9a
    • View Profile
Re: "Breeding" cold hardy avocadoes from supermarket seeds?
« Reply #54 on: December 19, 2022, 01:09:29 AM »
Seed sprouted from store Hass probably won't survive above-ground lower than about 23F, in Florida 8b. In my experience most survive occasional brief hard freezes (18-23F) as stumps and sprout back when it warms up. The ground is warmer and frost insulated versus the air around when it freezes, as long as the bad freeze isn't too extended.. They often survive, but sprout back with less vigor. I had one seedling grow 7 foot it's first year and put on a few branches and a foot or so of bark, but the next winter got to 19F, and it didn't grow past a foot for 3 years until it finally died, which may have actually been from drought. After trying at least 200 seedlings or so thats the result. Although some will grow back 2-10 feet after a couple mild years, I expect them to eventually be stumped again and probably never produce. I keep them around for the idea to use as rootstock in the future. However, a grocery store seedling is not a tested clonal rootstock variety, so it 'could' be a gamble using them as rootstock in a given area in the first place..
The mexican types I haven't had cold issues with themselves, but since these grafted varieties available around here are grafted on less cold hardy rootstock, the graft union must be buried, which could 'potentially' cause future problems (I haven't run into major issues burying grafts so far, to my knowledge, although I have read not to do it). I think burying the graft with a good barrier of perlite around the immediate trunk/graft area would be best to discourage potential rot fungus and pests from attacking the underground graft. Then I would put a layer of clean sand on top, to hold heat down when it does freeze hard (since perlite can be pretty loose and might dissipate heat faster without a barrier). I would not bury the graft in contact with rich soil, out of caution. Also I tend to put some limestone at the very top of the sand close to the trunk and pour normal strength miracle grow solution right on the trunk base when fertilizing. It contains some copper and sulfur, which I believe is a bit of a fungus preventative whenever the trunk/graft gets briefly drenched, as well as obviously fertilizing, but I would not go overboard and fertilize too much and also not in the cold months.
You could also mound the less hardy base/graft with bags of mulch/leaves/pine straw during bad freezes and uncover it in the spring. A few cinder blocks stacked up circling the graft packed in with leaves, styrofoam or other insulating material might also work but i cant tell you to what degree. Or try a combination of these techniques. I leave out the prospect of using Christmas lights because its not really feasible if you wanted to plant a number of these.
We're fixing to get a 21F freeze in the next few days..I may put a few tricks together on some seedlings just to see what may work best.
« Last Edit: December 19, 2022, 01:45:38 AM by 850FL »

 

SMF spam blocked by CleanTalk