Jump to content
IMPORTANT ANNOUNCEMENT ABOUT LOGGING IN ×
  • WELCOME GUEST

    It looks as if you are viewing PalmTalk as an unregistered Guest.

    Please consider registering so as to take better advantage of our vast knowledge base and friendly community.  By registering you will gain access to many features - among them are our powerful Search feature, the ability to Private Message other Users, and be able to post and/or answer questions from all over the world. It is completely free, no “catches,” and you will have complete control over how you wish to use this site.

    PalmTalk is sponsored by the International Palm Society. - an organization dedicated to learning everything about and enjoying palm trees (and their companion plants) while conserving endangered palm species and habitat worldwide. Please take the time to know us all better and register.

    guest Renda04.jpg

Does Cold Weather Actually "Hardened" Palms to Future Cold?


Alicehunter2000

Recommended Posts

Looking toward the future after our brutal winter, I'm hoping that my newly planted plants will be "hardened" to future events. I hear this term thrown around a lot, but have never questioned how this increased cold tolorance mechanism is supposed to work. Have there been any studies regarding exposing palms or plants to progressively colder temps in able to make them tougher?

It almost seems like an old wives tale that subjecting plants to cold stress would do anything other than harm them. Or is the old adage truly, and scientifically, correct.....whatever doesn't kill you, makes you stronger.

David Simms zone 9a on Highway 30a

200 steps from the Gulf in NW Florida

30 ft. elevation and sandy soil

Link to comment
Share on other sites

I wish this were true but i would say no, our summers are Tropical, High Humidity and Rainy..

Usually this produces softer tender foliage on alot of plants, more so than would be produced in a dyer time, people sometimes say this for Coconut Palms, but i don't believe it, but Green Verities are hardier than golds, i have both and one year the Gold was brown and the Green was fine, they both survived though and i doubt it would produce a seed that is hardier somehow than its counterparts.

Malabar, Florida. Zone 10a, East Central Florida.

Link to comment
Share on other sites

There's a two part answer to your question.

1) Palms become more robust and hardier from being in the ground for longer periods of time, but this has little to do with hardiness induced from cold.

2) Foliage that's exposed to warm humid conditions with warm nights isn't going to have the same degree of frost resistance than foliage that is gradually exposed to drier, cooler conditions with colder nights. This is why for example greenhouse grown plants are more tender than outdoor grown plants, at least in California. And that's why our nice Fall conditions in California with drier air and cool nights does a decent job at hardening off tender foliage.

Link to comment
Share on other sites

Id say once the palm is established in its spot for a couple season cycles its fronds are acclimated. There were several palms that lived through the 2011 spell of Texas- El Paso, that had trunk damage. Then even a year later were snapping because they had trunk damage.

I think once a palm is heavily damaged from cold, it is weaker then.

Current Texas Gardening Zone 9a, Mean (1999-2024): 22F Low/104F High. Yearly Precipitation 39.17 inches.

Extremes: Low Min 4F 2021, 13.8F 2024. High Max 112F 2011/2023, Precipitation Max 58 inches 2015, Lowest 19 Inches 2011.

Weather Station: https://www.wunderground.com/dashboard/pws/KTXCOLLE465

Ryan (Paleoclimatologist Since 4 billion Years ago, Meteorologist/Earth Scientist/Physicist Since 1995, Savy Horticulturist Since Birth.)

Link to comment
Share on other sites

Maybe part of the answer is that once a palm goes down to a certain temperature and survives, you know it can go down to that temp. And your not as worried the next time.

So hardened is a term should only be used for palms that have been slowly acclimated to cooler and drier temps and not palms that undergo sharp drops in temps.

What processes within the physiology of the palm require the process to be slow? I just don't quite get it..... either a plant can take a certain temp or it can't.....why slow acclimation?

David Simms zone 9a on Highway 30a

200 steps from the Gulf in NW Florida

30 ft. elevation and sandy soil

Link to comment
Share on other sites

David the link to that publication that I posted in the Polar Vortex thread I think actually addresses your question. I'm not too far yet into my reading, only finished the Intro, but there's already a mention of hardening near the end of that chapter when discussing orange crops in SoCal. It sounds to me like it could be more related to the weather somewhat preceeding the event and it's effect on the plant at that time (like in the case of fruit trees sending them into a dormant state earlier making them less affected when colder weather hits) and where the plant is in relationship to flowering for example rather than a result of cumulative cold experiences over years. Plant varieties will have their own natural tolerances ranges and other plant conditions like age, watering, health of the plant, etc. will also influence cold tolerance. I'm not sure the book specifically addresses palms, although date palms would fall into the agricultural realm for sure.

I believe when I was looking over the Table of Contents there was a section on hardening as well. I'm actually finding this 2005 U.N. publication to be an interesting read. Since it was co-authored by someone from UC Davis, it seems like there are a number of examples from California and Florida presented. For those PT members outside the U.S., there are also references to frost and freezes in other parts of the world. The other co-author was from Portugal.

BTW, I downloaded the pdf version from the website and should mention that the tables and graphs don't come out in a readable format in the pdf. I'm having to go back to the website to see them. Kind of a shame.

Also think there might be a typo on Page 13-14 when they mention oranges in SoCal. Think they meant to say Santa Clarita Valley instead of Santa Clara Valley. I live in Santa Clara Valley and while there are some orange trees here I don't think that's what they meant to say.

Zone 9b (formerly listed as Zone 9a); Sunset 14

Link to comment
Share on other sites

Looked ahead. Chapter 4 on Frost Damages goes into cellular hardening. Palms are mentioned.

Zone 9b (formerly listed as Zone 9a); Sunset 14

Link to comment
Share on other sites

Now some of my experience. Sun grown fronds present definitely a greater resistance to cold damage than the ones grown in shade. A palm that is actually in 'hibernation' is more resistant than one with active growth. A well fed vigorous palm is many times hardier than a weakling.

Link to comment
Share on other sites

Interesting.....now we are getting somewhere.....will definitely read when I get the chance. ...thanks. I have also noted the huge difference between healthy plants and nutritionally deprived ones.

David Simms zone 9a on Highway 30a

200 steps from the Gulf in NW Florida

30 ft. elevation and sandy soil

Link to comment
Share on other sites

Palms only harden to cold weather after they've experienced the cold. Therefore, spring growth is more cold tolerant than fall growth.

That makes no logical sense. Spring growth by definition involves growth that's not exposed to Winter cold but to Spring temps which are much warmer than late Fall temps due to much higher sun angles than in Fall.

Link to comment
Share on other sites

Palms only harden to cold weather after they've experienced the cold. Therefore, spring growth is more cold tolerant than fall growth.

That makes no logical sense. Spring growth by definition involves growth that's not exposed to Winter cold but to Spring temps which are much warmer than late Fall temps due to much higher sun angles than in Fall.

It is probably too late, and I am too cold to do this justice. There is something here, but it is not simple. Foliage does toughen up to cold, to a point. We get more damage here, when after a few warm winters, and a warm fall, we get zapped with a big cold front. We got a lot of damage this year after two warm winters. After two normal winters the damage would have been less. Things sometimes die here that are hardier further north.too, due to that same effect.. Spring growth comes forward in cool weather and is subject to cold during its growth. Summer growth is more tender. Can't explain it, it just is. I would far rather have normal winter cold, than a few warm winters like we just had, and then a colder one. This is why we have more damage this year, than in 2010 when it was quite a bit colder.

  • Upvote 1

In my post I sometimes express "my" opinion. Warning, it may differ from "your" opinion. If so, please do not feel insulted, just state your own if you wish. Any data in this post is provided 'as is' and in no event shall I be liable for any damages, including, without limitation, damages resulting from accuracy or lack thereof, insult, or any other damages

Link to comment
Share on other sites

Palms only harden to cold weather after they've experienced the cold. Therefore, spring growth is more cold tolerant than fall growth.

That makes no logical sense. Spring growth by definition involves growth that's not exposed to Winter cold but to Spring temps which are much warmer than late Fall temps due to much higher sun angles than in Fall.

It is probably too late, and I am too cold to do this justice. There is something here, but it is not simple. Foliage does toughen up to cold, to a point. We get more damage here, when after a few warm winters, and a warm fall, we get zapped with a big cold front. We got a lot of damage this year after two warm winters. After two normal winters the damage would normally have been less. Things sometimes die here that are hardier further north.too, due to that same effect.. Spring growth comes forward in cool weather and is subject to cold during its growth. Summer growth is more tender. Can't explain it, it just is. I would far rather have normal winter cold, than a few warm winters like we just had, and then a colder one. This is why we have more damage this year, than in 2010 when it was quite a bit colder. It is like plants let their guard down. Maybe they take up more nitrogen and put more energy into growth than they should, or would in a more conserative climate. We are advised here to cut back hard on nitrogen in the fall for just that reason.

In my post I sometimes express "my" opinion. Warning, it may differ from "your" opinion. If so, please do not feel insulted, just state your own if you wish. Any data in this post is provided 'as is' and in no event shall I be liable for any damages, including, without limitation, damages resulting from accuracy or lack thereof, insult, or any other damages

Link to comment
Share on other sites

Palms only harden to cold weather after they've experienced the cold. Therefore, spring growth is more cold tolerant than fall growth.

That makes no logical sense. Spring growth by definition involves growth that's not exposed to Winter cold but to Spring temps which are much warmer than late Fall temps due to much higher sun angles than in Fall.

The growth starts at the bud tissue. Since growth is very slow in winter, these cells will mostly remain unseen. When spring rolls around, these cells will mature as leaves and of course the current spring growth from the bud will be adapted to the spring environment.

Zone 7a/b Delaware

Unusual Plants

Link to comment
Share on other sites

  • 3 months later...

One thing plants can do is move the amount of water(inside) around,which changes the

amount of carbs(sugars)to water ratio,this would effectively change the freezing point.

I have always noticed that my Trachys are more resistant to cold after they have seen some,

the worst damage is always from a sudden change from warm to cold-there has to be

some hardening off of tissue that goes on because growth is slower in the cold.

  • Upvote 1
Link to comment
Share on other sites

Hardening is a real phenomena as anyone with a heated greenhouse can attest. I think there are two factors that contribute to hardening in California for palms compatible with a Mediterranean climate: cooler Fall nights and drier conditions.

In Florida, a Winter freeze that interrupts warm humid conditions is far more likely to cause damage at higher temperatures.

The only exception is for palms that decline in vigor when exposed to cool California nights. Those actually loose hardiness because they are stressed and not adapted to deal with a Mediterranean or arid desert climate.

Link to comment
Share on other sites

climate: cooler Fall nights and drier conditions.

These are 2 very big factors,cool/cold temps slow growth which is not as tender as faster growing tissue.

The palm being dry also helps,less water means a higher carbs/water ratio(lower freezing point)

and a drier climate encourages(demands)slower growth= harder tissue/less tender.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Recently Browsing

    • No registered users viewing this page.
×
×
  • Create New...