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Author Topic: Temperatures & plants. How low can it go? (Community research thread)  (Read 43871 times)

Saros

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After talking about growing experiences with some other member, I think it would be great to compile a list of Seedian's experiences with various plants and what minimum temperatures that have survived (or died from). I'm not quite sure how I'll organize this yet but since we're getting into the cold season here in the States, I thought it would be a good idea to get this thread started so we can start adding info to it.

Personally, I'm leaving some sacrificial plants out in my unheated greenhouse this winter to see at what point they die. I'm using this temperature logger to keep track of the temperature inside the greenhouse. ***I can't seem to get this logger to work on Windows 7 for some reason***

The "Temp (C)" column is meant to be the lowest minimum temperature reached in that particular environment. For the plants in my greenhouse, it's the minimum temp that the greenhouse reached and maintained for any significant amount of time. If they're outdoor plants, I try to go by the actual minimum temperature reached outside rather than the theoretical zone minimum because some years, it doesn't get close.

The "Hours" column is meant to be how long the plant was exposed to those temperatures.

I think adding any other details about environment would be useful. So if you have any additional information that might be relevant to the plant's survival (or demise), by all means, include it. I'm in favor of collecting as much data as possible even though it's going to be a challenge to display it all.

If anyone wishes to submit data anonymously for 'naughty plants', please PM me with the info and I won't include your name with the data.

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Botanical NameLived/DiedTemp. (C)HoursAgeZoneEnvironmentUser
Acacia acuminataLived-866AUnder coverprasada
Acacia acuminataLived-566AOutdoorsprasada
Acacia acuminataLived-366AOutdoorsprasada
Acacia acuminataLived-3.36<1yr6BUnheated greenhouseSaros
Acacia maideniiLived-98AOutdoorscunningplatypus
Acacia simplexLived08OutdoorsGreentoe
Acacia simplexDied-68OutdoorsGreentoe
Agave paryiiTBD-23happyconcafeSevere damage (mushy leaves), Probably died
Alicia anisopetalaDied-68OutdoorsGreentoe
Alicia anisopetalaLived08OutdoorsGreentoe
Anadenanthera peregrinaLived08<1yr6BUnheated greenhouseSaros
Anadenanthera peregrinaDied-28<1yr6BUnheated greenhouseSarosLeaves stopped opening/closing.
Anadenanthera sp.Died-98AOutdoorscunningplatypus
Argyria nervosaLived-28<1yr6BUnheated greenhouseSarosDropped leaves
Argyria nervosaLived08<1yr6BUnheated greenhouseSaros
AriocarpusLived2.2OutdoorsNew Wisdom
Artemisia absinthiumLived-98AOutdoorscunningplatypus
Asimina trilobaLived-9<1yr6BOutdoorsSaros
Banisteriopsis caapiLived12.78OutdoorsFrog PajamasSigns of cold damage
Banisteriopsis caapiLived7.28Outdoorsmarshmellow
Banisteriopsis caapi (Cielo)Lived1.681yr6BOutdoorsSarosSlight drooping to leaves. Soil was also dry, so that may have been the cold or lack of water.
Banisteriopsis caapi (Cielo)Lived28<1yr6BUnheated greenhouseSaros
Banisteriopsis caapi (Red)Lived281yr6BUnheated greenhouseSaros
Banisteriopsis caapi (White)Lived1.681yr6BOutdoorsSaros
BrugmansiaLived7.77OutdoorsGreentoeIn ground, died back to roots
Brugmansia sp.Died-98AOutdoorscunningplatypus
Calea zacatechichiDied-98AOutdoorscunningplatypus
Calea zacatechichiLived1.6<1yr6BOutdoorsSaros
Centella asiaticaLived-98AOutdoorscunningplatypus
Desfontainia spinosaLived-98AOutdoorscunningplatypus
Heimia salicifoliaLived-98AOutdoorscunningplatypus
Heimia salicifoliaLived-68<1yr6BUnheated greenhouseSarosDied back to roots
Heimia salicifoliaLived-181yr6BUnheated greenhouseSarosDied back to roots. Leafs re-emerged 4/10
Ilex paraguariensisLived-98AOutdoorscunningplatypusDied back to roots
Iochroma australeLived-98AOutdoorscunningplatypusDied back to roots, regrew quickly
Leonitis leonurusDied-68OutdoorsGreentoe
Leonitis leonurusLived08OutdoorsGreentoe
LophophoraLived2.2OutdoorsNew Wisdom
MammillariaLived2.2OutdoorsNew Wisdom
Melaleuca alternifoliaLived-98AOutdoorscunningplatypus
Mimosa hostilisLived2129BUnder coverMadPlanter
Mimosa hostilisLived49BOutdoorsMadPlanter
Mimosa hostilisDied-581yr6BUnheated greenhouseSarosDropped most of it's leaves
Mimosa hostilisLived-281yr6BUnheated greenhouseSarosLeaves stopped opening/closing, but bounced back after 1wk indoors.
Mimosa hostilisLived081yr6BUnheated greenhouseSaros
Mimosa hostilisLived1.682yr6BOutdoorsSaros
Mitragyna speciosaDied-98AOutdoorscunningplatypus
Monarda didymaLived-18<1yr6BOutdoorsSarosDied back to roots mostly. A few tiny leaves around base stayed green.
MutucanaLived2.2OutdoorsNew Wisdom
MyrtillocactusLived2.2OutdoorsNew Wisdom
NeoporteriaLived2.2OutdoorsNew Wisdom
Nicotiana alataLived-26<1yr6BOutdoorsSaros
Nicotina rusticaLived-98AOutdoorscunningplatypusDied back to roots
OpuntiaLived2.2OutdoorsNew Wisdom
Passiflora caeruleaLived-581yr6BUnheated greenhouseSaros
Passiflora caeruleaLived-1881yr6BUnheated greenhouseSarosDied back to roots.. It was in a pot sitting in the corner of a raised bed in my greenhouse. Last year it grew roots through the bottom of the pot and firmly planted itself in the bed. The potted portion of the plant died during the winter. I thought the whole plant died until I noticed passiflora growing out of the complete opposite side of the bed. Apparently it lived on under the soil in the bed and came back from the roots.
Peganum harmalaLived-188<1yr6BUnheated greenhouseSaros
Phalaris aquatica (AQ1)Lived-3.3<1yr6BOutdoorsSaros
Phalaris aquatica (AQ1)Lived-188<1yr6BUnheated greenhouseSaros
Phalaris arundinacea (Big Medicine)Lived-3.3Under coverPermieGing
Phalaris arundinacea (Big Medicine)Lived-188<1yr6BUnheated greenhouseSaros
Phalaris arundinacea (Yugo Red)Lived-3.38<1yr6BUnheated greenhouseSaros
PolaskiaLived2.2OutdoorsNew Wisdom
Psychotria "nexus"Lived108OutdoorsSunshine
Psychotria albaLived-68OutdoorsGreentoeDied back to roots.
Psychotria albaLived08OutdoorsGreentoe
Psychotria albaLived7.28Outdoorsmarshmellow
Psychotria albaDied-58<1yr6BUnheated greenhouseSaros
Psychotria albaLived08<1yr6BUnheated greenhouseSaros
Psychotria viridisTBD108OutdoorsSunshineExtensive cold damage to 8" juvenile plant
Punica granatumLived-98AOutdoorscunningplatypusHawaiian seed
Punica granatum var. nanaLived-682yr6BUnheated greenhouseSaros
Salvia divinorumDied-98AOutdoorscunningplatypus
Salvia Divinorum (bunnell)Died-2.2OutdoorsSeed Collector
Salvia Divinorum (la fuerza)Lived28<1yr6BUnheated greenhouseSaros
Salvia Divinorum (la fuerza)Lived1.681yr6BOutdoorsSaros
Silene capensisLived-17.87AOutdoorsAuxin
Silene capensisLived-18<1yr6BUnheated greenhouseSaros
TephrocactusLived2.2OutdoorsNew Wisdom
TrichocereusLived/Died-98AOutdoorscunningplatypusIn ground. wet winter. living cactus developed tip rot but bounced back in the spring.
TrichocereusLived2.2OutdoorsNew Wisdom
Trichocereus bridgessii Lived7.77OutdoorsGreentoe
Trichocereus candicansLived7.77OutdoorsGreentoe
Trichocereus glaucasDied-12.78AOutdoorsAuxin3 day cold spell of -13.3, -12.7 , -12.2C weather. Froze solid.
Trichocereus macrogonusDied-12.78AOutdoorsAuxin3 day cold spell of -13.3, -12.7 , -12.2C weather. Froze solid.
Trichocereus pachanoiLived7.77OutdoorsGreentoe
Trichocereus peruvianusLived7.77OutdoorsGreentoe
Trichocereus terscheckiiLived-12.288AOutdoorsAuxinRepeated nights at -6.6C
Trichocereus terscheckiiDied-12.78AOutdoorsAuxin3 day cold spell of -13.3, -12.7 , -12.2C weather. Froze solid.
Voacanga africanaLived08<1yr6BUnheated greenhouseSaros
Voacanga africanaDied-58<1yr6BUnheated greenhouseSarosLeaves curled and froze solid
« Last Edit: October 17, 2014, 01:41:22 pm by Saros »
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Mandrake

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Re: What survives at what minimum temperatures?
« Reply #1 on: November 11, 2013, 09:31:27 pm »

A reference guide for plant hardiness in regards to temperature would be very useful. Most of us have wondered whether one plant could be safely left outside during the winter, or whether we should plant it outdoors at all. I'd surely look forward to resolve these issues with a data list and a thermometer.

Both information sourced in good literature and personal experimentation, specially around valuable plants for the community, will be very welcome.

Thank you for the thread,

Mandrake
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Sunshine

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Re: What survives at what minimum temperatures?
« Reply #2 on: November 11, 2013, 09:39:41 pm »

I just set one of my rooted la fuerza salvia cutting outside, out of the wind. It is around 4 inches tall. The current temperature is 47F and the time is 3:37pm. I'll update if anything changes.
« Last Edit: November 11, 2013, 11:41:43 pm by Sunshine »
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Saros

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Re: What survives at what minimum temperatures?
« Reply #3 on: November 11, 2013, 09:54:55 pm »

It might also be useful to make note of how long the cold temperatures last when possible.

I suspect that one of the reasons my Heimia s. survived all winter long in the unheated greenhouse was because the lowest temperatures didn't last more than 8 hours or so. After sundown, the temps slowly drop until it just about equalizes with the outdoor air. Then as soon as the sun hits it in the morning, it quickly heats up again. If it didn't jump back up above freezing each day, I'm not so sure they would have had the same survival rate.
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MadPlanter

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Re: What survives at what minimum temperatures?
« Reply #4 on: November 11, 2013, 10:51:34 pm »

The mimosa hostilis I have here have survived multiple days of straight exposure to 40F or slightly lower at night. I do however bring them at least under cover at below 35F. Maybe they could handle it but I just am afraid to hurt them.
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cunningplatypus

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Re: What survives at what minimum temperatures?
« Reply #5 on: November 11, 2013, 10:54:12 pm »

Saros,

An excellent question! I've also been experimenting to see what manages to hang on through the winter. I've taken some casualties, but it's all in the name of science. 

I live in the Pacific northwest, zone 8a (minimum temps 10 to 15 degrees Fahrenheit). Winters are very wet.

Here are some success stories for me from last winter, as well as some failures. Everything was in-ground, exposed to the elements.

Success in hardiness zone 8a

Iochroma australe (died back to the roots, regrew quickly)
Ilex paraguariensis (Yerba mate. Died back to its roots, which is not ideal for slow-growing, foliage-valued plants)
Heimia salicifolia (Sinicuichi)
Melaleuca alternifolia (Ti Tree)
Acacia maidenii
Punica granatum (Pomegranate, Hawaiian seed)
Centella asiatica (Gotu kola, one of the varieties)
Artemisia absinthium (Wormwood, no surprise)
Nicotina rustica (died back, but lived!)
Desfontainia spinosa

Failures

Salvia divinorum
Mitragyna speciosa (no surprise, really)
Calea zacatechichi
Anadenanthera sp.
Brugmansia sp.

Mixed success/failure would be my in-ground Trichocereus cacti.

They took the full rain assault all last winter, completely exposed to the elements. None died, but almost every one developed tip rot. They all recovered nicely, and pumped out the pups this summer.

This winter, I'm trying to overwinter in-ground...

Psidium cattleianum (Strawberry Guava)
Psychotria alba
Moringa oleifera (Drumstick Tree)
Silene capensis (Dream Root)
Withania somnifera (Ashwaganda)
Andrographis paniculata

I think there are a lot of variables that may make or break a plant's survival in marginal areas. Most importantly, I'd hazard that proper mulching might make the difference.   
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Sunshine

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Re: What survives at what minimum temperatures?
« Reply #6 on: November 11, 2013, 11:40:15 pm »

Its been 2 hours. The temperature has dropped 3 degrees and it is now 44F. The plant looks fine. I'll leave it for a few more hours.
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fairdinkumseeds

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Re: What survives at what minimum temperatures?
« Reply #7 on: November 12, 2013, 01:05:05 am »

I don't have much cold weather gardening experience, (or plan on getting any if I can help it.) But was told by an "expert" friend that mulching with lawn clippings was a good way to protect plants from the heavy frost, so I rushed around and mulched all the seedling fruit trees in couple rows as there had been frost predicted a couple months after we first arrived.
We had a big frost (well big for here) and the ones without mulch, which I didn't end up getting done in time, only about 10%-20% got a bit of leaf damage, nothing serious, but the ones with a thick donut of lawn clipping only 60% lived, mostly the stonefruit, and they all got really hammered, looked crook and died back. Same plants in both lots of rows, same open flat ground. Various guavas, custard apple, jackfruit, moringa, dates and stone fruit mostly.
I think the steam from the fresh leaf matter caused more ice on the roots and trunk? Whatever was the cause, I don't recommend fresh lawn clippings! Wasn't happy at all.
I would have thought that the moisture would trap heat and take longer for the temp to drop, but now I reckon that dry is better for some reason. Maybe less conductivity?
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Dry tropics
Hot very dry Summers, mild wet Winters.
Record coldest at home 6c, hottest 49c!
Annual rain was 1141mm, now only 350mm! 
Average temp is 16c-31c
Plant suggestions?

Sunshine

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Re: What survives at what minimum temperatures?
« Reply #8 on: November 12, 2013, 01:28:49 am »

Going on 4 hours and the temp hasn't dropped any in the last 2. Its still 44F and it looks fine. No doubt it would grow slower at temperatures this low. I don't think it would die though.
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Auxin

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Re: What survives at what minimum temperatures?
« Reply #9 on: November 12, 2013, 02:34:43 am »

Silene capensis survives semi-arid zone 7a winters without protection, mine are actually flowering again right now after the first frosts.
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Saros

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Re: What survives at what minimum temperatures?
« Reply #10 on: November 12, 2013, 03:32:13 am »

Auxin, that's great to hear. I suspected they would hang in there longer than most. Mine are blooming like crazy right now as well. Hopefully I'll have a bunch of seeds to share soon:)
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PermieGing

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Re: What survives at what minimum temperatures?
« Reply #11 on: November 12, 2013, 04:01:13 am »

Something that could inspire some scientific experimentation is putting some of these somewhat questionably cold hardy plants near lots of stone, like a stone wall or in the middle of a bunch of stones on the ground. The stones theoretically absorb solar heat and release when not exposed to the sun...

Food for thought
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Sunshine

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Re: What survives at what minimum temperatures?
« Reply #12 on: November 12, 2013, 04:40:45 am »

Its been 7 hours since I put it outside. It is now 43F. Its supposed to get down to 30F tonight so I'm going to bring it inside. We'll see tomorrow morning if the cold effected it.
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prasada

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Re: What survives at what minimum temperatures?
« Reply #13 on: November 12, 2013, 04:33:01 pm »

 I took some readings of  Acacia Acuminatas last night . The predicted low was -4c.
  Used a digital thermometer with three probes, one in soil,one for inside ambient temp and one for outside ambient temp. The plants ,in pots ,have remained outside for light and temperature acclimation .

 At 8pm     soil temp= 41.3f/5.1c     at 3am  34.5f/1.3c   at 5am 32.7f/.38c    at 9am 31.1f/0.4c
indoor ambient air  =36.8f/2.7c                   30.9f/-0.5c               32.5f/0.27c              45.1f/7.2c
outdoor ambient temp35.3f/1.7c                 29.1f/-1.6c               27.6f/-2.4c               31.7f/-0.16c

 so it looks like soil temp went below freezing , but i would suspect there is still some latent heat coming out of the water as it changes state  from a liquid to solid, some components of the soil could be colder than the water.   This cant be compared to a plant in the ground that is buffered by the earth temp.
 Oh yea ,the plants look fine.
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Saros

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Re: What survives at what minimum temperatures?
« Reply #14 on: November 12, 2013, 07:27:39 pm »

prasada, that's great to be able to get such detailed measurements. I need to get myself a thermometer for soil as well. That might be an interesting number to keep track of for this.
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