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[Saros]

I'm trying to keep track of this data in a spreadsheet for now and will update the table on my original post as I make changes to the spreadsheet. I've added all the info we have so far and tried as best I could to fill in the gaps using zone info and historical weather data. So, please double check that I didn't make mistakes or any outrageous assumptions while filling in the gaps=) I figure this will be constantly changing as we gather more data.

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[PermieGing]

Phalaris big medicine

I have it potted on my fromt porch out of a frostable area. However its snowing atm and has been frosting and below 32f many nights so far and its pulling through.

Ill update with more info once its interesting enough

[Greentoe]

It hasn't gotten very cold here yet this year so I haven't been able to get any new results yet, but I have something to add from pass winters.

I've been growing brugmansia outside for three years now. 7.77C is the lowest the temp has gotten in 2011 and 2012. The plants have lived through this. It probably didn't stay at that temp for more than a couple hours but they did survive. The first winter I had them outside I cut them down about 4 inches above the ground around the beginning of December and made a bunch of cuttings from them. The next spring the plants came back from the roots. Their was one in a pot that was left uncut. The top of the plant died, but it also came back from the roots.

The next winter I only cut back a couple of them and left most of them alone. They dropped their leaves a couple of branches shriveled up and died, but most of the plant above ground survived. This years they grew giant compared to the year before. Easily 8 ft some maybe even taller. They looked pretty nice.

I believe they can survive colder temps if you cut them back and mulch over the roots well. They will then grow back from the roots in the spring.

Also all of my trichocereus cacti have survived these same conditions outside in pots. I have bridgesii monstrose, candicans, pachanoi, and peruvianus that have all tolerated the winter outside here.

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[PermieGing]

So it got to like 26F last night and the phalaris big med is fine on my front porch, but frost cant get to it where it is at currently. I plan on doing more experimenting and observing when i propagate it alot in the spring

[Seed Collector]

It got 28 degrees Fahrenheit here last night. It killed 2 Salvia divinorum plants of mine, Bunnell strain. (all that were outside died).

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[Mandrake]

Thank you everyone, and particularly to Saros for the good work. We're starting to compile a great resource here.

This thread is now moved and stickied in the Growing Questions and Answers section, in the Gardening Area.

Keep the data coming!

Cheers,

Mandrake

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[Greentoe]

Well tonight I'm going to find out if alicia anisopetala can survive freezing temperatures. I went to cut one of my plants back and take it inside today and noticed one of the vines had grown roots where it was on the ground. I left the rooted section of vine outside. Have my fingers crossed that it'll make it.

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[Sunshine]

I've read that the fully grown caapi species can survive near freezing temperatures quite well for short durations(overnight).

[prasada]

  Last saturday the temperature went down to -9c , the acacias were on an unheated  deck out of the wind.
The temp at the plants was -8c or colder all night, the soil went below freezing ,-2c. The plants look fine.
They have gone through at least three -5 nights and sub-zero days.I put them outside for some sun one day,
 forgot about them, and it snowed. Didnt seem to bother them either.
The only thing I've noticed is the tips look dry,but they did that indoors too.

[Saros]

Nice prasada. That seems to hold true with mine as well. It's been down to -5c in the greenhouse a few times and likely even lower for a short time. The acuminata seems unphased.

The top part of one Psychotria alba died back but the lower part of the plant is still alive.
Phalaris Big Med, Yugo Red, and AQ1 are all doing file
Passiflora caerulea is still untouched
The Heimia salicifolia is starting to drop some leaves (and grow smaller ones closer to the base and stem)
Syrian rue is still alive.
Silene Capensis is still flowering
The Mimosa hostilis & Anadenanthera peregrina have dropped most of their leaves now or what's left would probably come off with a vigorous shake. I'm not sure if they're still alive or just dormant at this stage.

So far the winter has claimed
1 Argyria nervosa at -2c
3 Voacanga africana at -5c

[TBM]

I accidentally left a window open overnight when I was visiting relatives for Thanksgiving, it got down to 30°F outside but I'm not really sure how cold it got inside the apartment (window was only open ~4"). All of my psychotria (viridis and alba) were killed from the cold; the rest of my plants appear to be unaffected, it seems it got just cold enough to kill the psychotria but not enough for anything else I'm growing to die... I guess it could've been worse It seems psychotria (at least while it's >1 year old) is quite sensitive to the cold.

[Saros]

Aw man, I'm sorry to hear that TBM. I did that too a couple months ago while the weather was unpredictable. I didn't loose anything from it but it was a pretty awful feeling when I realized what I did.

I think maybe another factor with your Psychotria was the shock of it... Having been in fairly favorable conditions indoors and then the sudden drop to near freezing temps might have just been too much of a change for them.  The ones that I have in my greenhouse were both started from leaf cuttings sometime around May, but they've been slowly acclimating to the lower temperatures with the change of seasons. Still, I'm half suspecting that they're zombie plants.. by all rights, they should be dead.. they just don't look like it yet.

[PermieGing]

My phalaris big medicine has survived to around 20F while under my front porch.

Somehow, my new aq1 and yugo red survived that temp when i left em out accidentally as well, for 1 night. I dont recommend it lol. It scared me.
The yugo red has like 5 blades and the aq1 maybe 25.
Crazy
I wont be letting it happen again until i have propagated them alot

[Auxin]

Trichocereus terscheckii, barely survives average zone 8a winter, maybe.

So I had heard this stated before and last year tried to test it. Last winter turned out abnormally warm for my area- lowest low of 10°F, a quarter of night lows were 20°, nearly all were below 30°. A Zone 8a winter, the three golf ball sized T. terscheckii 'Valle Fertil' seedlings I left out survived fine.
This year, on the same week as last years 10° low, we had a record 3 day cold spell of 8, 9, and 10° lows. Those same, now slightly bigger, seedlings and a typical curved spine T. terscheckii the size of a huge grapefruit all froze solid and died (as did two T. glaucas and a T. macrogonus, none of which I expected to survive anyway).

If zone 8a at least be ready to insulate terscheckiis for the coldest nights, if colder bring them in for sure.
Remember USDA zone is an average and any one winter can easily vary by two whole zone rankings.

(F-32)/1.8=C

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[happyconcacti]

Agave paryii, severely damaged (mushy leaves), likely dead at -9°F (-23C)