average temperature and palm growth

[flplantguy]

Has anyone done any studies or observations of plants under specific average temperature profiles? A good example is heat stress and when it becomes damaging. It's not the high and the low temperature that determine average growth, but the average temp of the day, month, etc.  When that ideal is exceeded too far one way or the other damage ensues, like chill damage on cocos or heat damage on ceroxylon. My theory is an average temp of 80 or higher is stressful to subtropicals, and above an average of 85 its damaging to them or deadly. A constant temperature of 85 for days would do this, as would nights of 77 and days of 92 with sharp temp increases after sunup, like a heatwave would do.  Hawaii would never see this and grows things that fail in Florida, im wondering if this is part of why. Add on other stressors like fungus and pH issues, and catostrophic failure occurs.

[Silas_Sancona]

23 minutes ago, flplantguy said:

Has anyone done any studies or observations of plants under specific average temperature profiles? A good example is heat stress and when it becomes damaging. It's not the high and the low temperature that determine average growth, but the average temp of the day, month, etc.  When that ideal is exceeded too far one way or the other damage ensues, like chill damage on cocos or heat damage on ceroxylon. My theory is an average temp of 80 or higher is stressful to subtropicals, and above an average of 85 its damaging to them or deadly. A constant temperature of 85 for days would do this, as would nights of 77 and days of 92 with sharp temp increases after sunup, like a heatwave would do.  Hawaii would never see this and grows things that fail in Florida, im wondering if this is part of why. Add on other stressors like fungus and pH issues, and catostrophic failure occurs.

Pretty sure the nuts and bolts of the why in the question were laid out in the link i posted in the " Tropical plants " section here.. 

All living things have a range of temperatures / other climate- related things that they evolved to tolerate..  Exceed it, either way,  and the trouble starts.. 

Some only evolved to tolerate a fairly narrow range of those conditions while others " escaped the box " ..so to say, and can tolerate / positively respond to... a far wider range of conditions w/ out experiencing too much stress  ..though they too have a breaking point.. Everything does. 

Creosote Bush and Ocotillo are two examples  -on a regional scale-  of plants that " escaped the box " ...You can encounter them here, where it rarely gets " cold " ...and in places like W/ TX, N.M, NV or UT where it can get fairly chilly at times during the winter...  They'll both even grow in less hot S. Cal, close to the coast, can be encountered down in southern Baja, and at the far south end of the Mexican Plateau, not too far from Mexico City.. There's even an  iNat observation of Creosote Bush from just east of Carson City Nevada.. 

That's a pretty impressive distribution / range of conditions, soil types, etc either of those two plants evolved to tolerate.. 

Washingtonia robusta would be a good Palm specific example of the same general idea.. 



Contrast that with all sorts of stuff that is much more temperamental and thus restricted.. 




I myself have always liked how Orchid growers laid out the various temperature tolerances they can handle  and apply that same scale to everything else with leaves ....because...  ..it makes perfect sense.. 

Since no single plant / group of plants is an island  ...if a specific, high elevation Maxillaria can't handle too much heat ...or cold ....And/Or dryness, etc..  Any / every other plant that grows where that specific Max. species grows may be just as sensitive to those same limiting factors, depending on their individual distribution ( IE:  Does the same Begonia species that grows on that rock next to the Max. also grow at a much lower ..and hotter / drier elevation,  for example ). 



Coming down to the " observed in my tiny box " scale,    here at least,  it's very easy to know when certain plants will either " slow their roll " ..or shut down  completely  ..until temperatures -which have exceeded their specific tolerance threshold- drop back into that  comfy - for - them zone this time of year.. 

Two types of Ficus that sit next to each other  ..One native,  Other from a wetter -yet fairly hot- area in Asia, that is planted everywhere here...  Native one seems to shrug at our brutal summers/ lots of sun, even though it is small and in a pot.   Non native -and much larger- sp.,  planted in the ground years ago?   looks like someone took a torch to the top of it's canopy,  this year esp.  Far worse damage to it  -from the last 3 dry and sizzling summers-  than any amount of " cold " i've seen in the winter. 

...If i were laying out such observation in an article, i'd say the heat- related damage starts after a week at / above 110F 

Not sure how much stress the 85-90+F lows  we see at the same time adds to the negative effect the heat has on that Ficus / other specimens of the same sp. nearby though.  That said, thinking about it, those nights probably add their own amount of stress..

Two Senna sps planted less than 30 ft apart?  = same idea..  ..Though that one is a little more intriguing..  Native comes from mid elevation areas just south of me, where it doesn't get quite as hot as here.  Rains more down there too.   Started it from seed back in Feb. and intentionally placed it in the hottest exposure out back as a test.. 

Other,  picked up just to see what it might do,  originates from low elevation areas in S. & Central America,  and parts of the Caribbean -i think- 

...Which of the two looks awful right now??? 

..Non native Senna ...Which i'd think would tolerate heat and episodic dryness decently since it's origin is areas that can experience both of those conditions. 

As soon as the heat really kicked in,  all it's lush growth put on this spring burned and fell off.  Was also attacked by some sort of scale or fungus again, before all the foliage exposed to the sun dropped.  Second year that has occurred under the same conditions / temps. 

Once it isn't 100 / 100+ every day, it pushes new growth ..that hangs on, and isn't bothered by bugs / fungus ..or whatever it is that gets it when it's apparent tolerance limit has been reached / exceeded. 


Native sp.? ..a bit tired of the heat atm,  ..but otherwise looking alright. It is just starting to show obvious signs it's stressing out. ( getting the same bug / fungus that shows up on the non native Senna )

...Have noted numerous other examples of the same general pattern since moving here..




As for any Hawaii vs Florida thoughts?   ..Is like comparing Citrus to Prunus  ... = Two very different plants, ..even if both bear " fruit "..  


Hawaii isn't connected to  ..or anywhere near..  a large land mass that can exert X Y or Z influence on it's climate. 

Florida's climate is definitely influenced by the land mass it is near / attached to.  

Added up,  If a plant from another island which has a similar temp. profile to Hawaii,  is grown on Hawaii,  it's not a surprise it may excel there rather than anywhere / or in most of... FL.  

That's just how things work out sometimes.. ...anywhere someone lives.  

[flplantguy]

Thats kind of what i mean, not the anecdotal understanding of gardening over time, but a controlled study of the particulars of the way it happens. The "nuts and bolts" of the process, like when a phytotoxic effect occurs that we know happens, but the actual chemistry involved being explored and explained. That would involve labs and machinery, so would be unlikely to have been done on something unless its a very imprtant crop.

[sonoranfans]

12 hours ago, flplantguy said:

Thats kind of what i mean, not the anecdotal understanding of gardening over time, but a controlled study of the particulars of the way it happens. The "nuts and bolts" of the process, like when a phytotoxic effect occurs that we know happens, but the actual chemistry involved being explored and explained. That would involve labs and machinery, so would be unlikely to have been done on something unless its a very imprtant crop.

Dig and you will find, don't reinvent the wheel.  This should keep you busy for a while.  There is not one answer of perfect temperature as there are different genetic adaptations and also different climates, soils and causes of heat stress.  Heat stress can be due to dehydration combined with high air temps or solar irradiation etc.,

https://pmc.ncbi.nlm.nih.gov/articles/PMC7795586/

this one talks about how roots are what is damaged first, root temps matter more than air temps.

https://pmc.ncbi.nlm.nih.gov/articles/PMC10649217/

 

[sonoranfans]

I dont think 85 degrees discourages growth at all, here is a syngenta soilmap showing my area is about 85-87F for the soil during our peak grow season.

https://www.greencastonline.com/tools/soil-temperature

a little cooldown in the beginning of august but its right back up there and my yard seems at peak growth last couple months.  Its raining the last few days and soil and air temps are within a few degrees.

[flplantguy]

Thats an interesting site, ill have to bookmark it.  I think some of what i have seen this summer is a phytotoxic effect from a stribulurin fungicide, the dead areas on leaves spread after they are watered as well as heat; orchids treated with some pesticides do the same thing.  The fix for them is no water until the chemical dissapates, can't do that with these guys.

I think plants in the ground that have a deeper root system can use that like a cool sink, since the soil is cooler down deep in summer. Then the plant is cooler on average which wont be the case in a pot.  Multiple factors all coming together to disrupt systems and cause damage.

[sonoranfans]

9 hours ago, flplantguy said:

Thats an interesting site, ill have to bookmark it.  I think some of what i have seen this summer is a phytotoxic effect from a stribulurin fungicide, the dead areas on leaves spread after they are watered as well as heat; orchids treated with some pesticides do the same thing.  The fix for them is no water until the chemical dissapates, can't do that with these guys.

I think plants in the ground that have a deeper root system can use that like a cool sink, since the soil is cooler down deep in summer. Then the plant is cooler on average which wont be the case in a pot.  Multiple factors all coming together to disrupt systems and cause damage.

Plants in a pot can get hotter especially if sun exposed, where solar heating can ramp up pot temps.  Wet soil doesnt heat up so fast as evaporation(natures air conditioner) will draw heat from the soil.  The in ground soil is connected to a massive heat sink so temps rise more slowly compared with a pot.  Pots are on their own, they heat up readily, probably should be monitored for temperature if you are limiting watering.  The soil temp site also measures soil temperatures at 4" depth, roots in the ground go deeper to cooler soil.  

[flplantguy]

Anything that was showing stress was moved to shade if its not there already, but a one gallon pot wont be cool no matter how much shade it gets of its 95 degrees out most of the day.  the plants having issues didnt last summer at all, but add the chemical fungicide and i guess that tipped the balance. 2 days of temps in the upper 70s with rain helps but the damage may be done already.

[sonoranfans]

why did you use a chemical fungicide?

[flplantguy]

18 hours ago, sonoranfans said:

why did you use a chemical fungicide?

Last ditch attempt to try and stop a fast moving fungus.  I was going to likely lose them anyway so i gave it a shot. It did work, but also damaged them a lot. I know now what to do to prevent it (no low crowns near open sand that can splash into the crown, just like orchids) so next time on a bench in the greenhouse will prevent it. 

My yard is mostly native including the many microbes; it has taken full trees that were cut down (dead already) from large piles to almost nothing in three years from fungus doung its work (thankfully).  The plants arent in an enclosed area now either, but all that will change soon. I'm used to a greenhouse too and how to manage it, so that will help keep them safe. And allow me to expand my collection lol.