Can someone set me straight on the effect of cooler fall nights?

I was told by someone I trust for much plant knowledge that the trees actually prefer a hot day with an evening in the low 70s because thats when they “recover,” for lack of a better word.

 

whats the take on this? It would seem to me that a cool period would allow the cells of the tree to grow and replicate with less stress that during the peak of the day.

it’s probably pure coincidence but i have also noticed that many of my trees tend to open their new leaves overnight as well.

38 minutes ago, byuind said:

Can someone set me straight on the effect of cooler fall nights?

I was told by someone I trust for much plant knowledge that the trees actually prefer a hot day with an evening in the low 70s because thats when they “recover,” for lack of a better word.

 

whats the take on this? It would seem to me that a cool period would allow the cells of the tree to grow and replicate with less stress that during the peak of the day.

it’s probably pure coincidence but i have also noticed that many of my trees tend to open their new leaves overnight as well.

My observation with flowers is that they do there work at night in the morning they look completely different than in the afternoon after a full day of sun one would presume temperatures must play a role there somewhere the Australian kangaroo paw flower does not l8ke to much variation in temperature if too big a difference in temperature in high to low temps the flowers just don’t like it 

In this same vein: my multiple hibiscus varieties were in constand bloom from March throuh May. Then the heat came and they ground to a halt. They continued vigorous green growth, even ahowing multiple buds, but they have not opened since then. I noticed the same thing all over my area for many Hibiscus plants. There were some i saw blooming, but they were in very shaded areas.

I have to surmise that there is some stress from heat in this plant which is causing it to not want to bloom. If they had just seemed to go dormant i would say they were unhappy- but all of them are getting generous water multiple times per week and are very lush green and growing

 

 

From my viewpoint, it seems to be different for each species. 

Just judging from what I routinely see in Central Florida, tropical genera like coconuts, Veitchia, etc. tend to like milder nights because this keeps the soil temperature further above 60F where they can metabolize the nutrients they need for growth.  Palms from cooler climates like Howea and Trachycarpus tend to like it more consistently cool as they often come to a screeching halt when they are subject to consistent temperatures over 85F.  Genera like Chambeyronia and Satakentia don't seem to mind hot days or cool nights as long as they aren't subjected to repeated frost or all day direct overhead sun.  A big reason why the latter, and similar genera like Archontophoenix, have become popular along the I-4 corridor is that they don't mind the cool nights and they grow well under canopy.

My yard has at least one species in all of the above genera, so there is always something that is happy vs. something that isn't depending on the time of year.  Fall and spring are usually the times of year where the bulk of the species are happy, so I tend to take photos and give tours during these times of year.

11 hours ago, kinzyjr said:

From my viewpoint, it seems to be different for each species. 

Just judging from what I routinely see in Central Florida, tropical genera like coconuts, Veitchia, etc. tend to like milder nights because this keeps the soil temperature further above 60F where they can metabolize the nutrients they need for growth.  Palms from cooler climates like Howea and Trachycarpus tend to like it more consistently cool as they often come to a screeching halt when they are subject to consistent temperatures over 85F.  Genera like Chambeyronia and Satakentia don't seem to mind hot days or cool nights as long as they aren't subjected to repeated frost or all day direct overhead sun.  A big reason why the latter, and similar genera like Archontophoenix, have become popular along the I-4 corridor is that they don't mind the cool nights and they grow well under canopy.

My yard has at least one species in all of the above genera, so there is always something that is happy vs. something that isn't depending on the time of year.  Fall and spring are usually the times of year where the bulk of the species are happy, so I tend to take photos and give tours during these times of year.

I can’t say for sure, but hot sunny days and hot summer nights (80+F) seem to really speed up species like Pseudophoenix, and various Carribean and Cuban palms.  I agree it clearly varies from species to species, probably correlating to their native conditions. 

Edited September 24, 20232 yr by Looking Glass

Some are faster in the heat as long as they get enough water, some like it a bit cooler overall though.  No general rules for all palms or trees, they are genetically adapted to their habitats.  The bigger factor for many plants is soil temperature, not air temps I think.  A ten degree difference in soils temps has been observed to create a ten fold higher microbial activity(metabolism) of the beneficial microbes that supply the tree with nutrients.  This dependence on microbe activity also has variations as some species dont need the bugs as much as others.  I generally get better growth in my palms when its hotter, a stifling hot.  This does occur with more rain (or irrigation) here int he heat so those factors of air/soil temp are correlated with more rain, its even more complicated than it first looks.  My BxJ hybrids are definitely more robust growers in cooler weather (highs under 80F) when most other palms slow to a crawl.

In my gardens I will say the tropical to semi tropical palms that I am able to grow will grow the fastest the warmer the nights are as well as the hotter the days are as long as they receive lots of water.

This I have witnessed with Roystonea, Archontophoenix, Clinostigma, Wodyetia, and Chambeyronia. For me they all grow fastest when it’s as close to 100 degrees as possible if not over 100 during the day and the night time temps do not dip below 70.

This is inland Socal where we do not have Florida’s humidity or hot nights. But on our hottest days the night will not dip below 75-80 degrees.

I typed this last night and didn't post, let's see if it still makes sense!

It's a lot of factors that do different things that cause the plants temp preferences to differ among species.  Cactus are CAM plants for example, so their metabolism runs at higher temperature during the day and the stomata open at night to finish the processes that cannot happen in the extreme temperature the cells reach in daylight.  They "breathe" at night to limit water loss, which is part of why new leaves and flowers tend to open at night in the higher humidity levels.  I think with some other plants the temperature isn't deadly by itself, but the environment that is changed as a result causes issues like a rampant microbe that usually doesn't cause problems suddenly causing disease.  Hot humid nights can be a combination of these issues; add a disrupted night metabolism, fungus naturally present in the environment, and a weather pattern that allows the fungus the proliferate in the plant's weakened systems and you have a mush pile instead of a "chrysalidocarpus dicipiens".  Some plants have little to no adaptation for extreme weather and others are reliant upon it, so knowing the plant helps as well as where it comes from and the extremes it experiences there.  The chemistry of "why" is more complex than that I'm sure, but plant physiology was not an easy class for me lol. 

On 9/23/2023 at 6:37 AM, byuind said:

In this same vein: my multiple hibiscus varieties were in constand bloom from March throuh May. Then the heat came and they ground to a halt. They continued vigorous green growth, even ahowing multiple buds, but they have not opened since then. I noticed the same thing all over my area for many Hibiscus plants. There were some i saw blooming, but they were in very shaded areas.

I have to surmise that there is some stress from heat in this plant which is causing it to not want to bloom. If they had just seemed to go dormant i would say they were unhappy- but all of them are getting generous water multiple times per week and are very lush green and growing

 

 

Not to say it wasn't occurring, but don't recall noticing this much w/ Hibiscus while in FL..  The 100's.. i'd trim at the nurseries i'd worked at, esp in Sarasota, seemed to flower pretty consistently in sun or shade March-ish - about November..  Flowers did last last longer in shade though..   My own Hibiscus seemed to follow a similar pattern ..though flowering on my  X " Creole Lady " seemed to  take a quick " break " right before the rainy season set in ..in say late May - early June.

On the other hand, here, the abused red one that grew out front ( I chopped it down earlier this summer -to put it out of it's misery- )  definitely had a pattern similar to what you noted there.. Would present flowers during the warm / marginally hot spring, ..then completely shut down come June when the " outdoor furnace " was cranked to " extreme ", overnight lows esp.  A neighbor's, that sits in more shade in their yard,  also slowed to a crawl ..but has had at least a couple flowers on it through 55 days of 110+ highs / 36 nights at / above 90.

W/ the abused one, once night time lows returned to more reasonable levels ..right about now,  i'd get another burst of flowers / growth.

In CA, these flowered all year, though there too, i'd notice two " prime " flowering  times ..one during mid/ late Spring,  and the other in late summer / earlier Fall..

This year esp, the effect of this summer's extreme heat on -everything, was very obvious, even things that will stiff flower in the summer.  Other stuff ..that didn't burn or cook, also slowed to a very noticeable crawl for several weeks. 




Overall, the ideas on how cooler / warmer nights effect plant growth / reproductive cycles is correct ..with a caveat or two.. 

Soil temp definitely influences growth patterns, but, if air temps are still cool- ..ish / cooling,  but the soil is warming / still warm,  you'll see growth, ..just maybe at a slower rate  ...until the air temps catch up to the soil temps.  This would be something you might see in Fall / early spring, or during extended periods of cooler weather ..when it should be warmer.. 

Obviously, here, our extreme heat creates enough stress to really slow down any plants sensitive to it  to a crawl  ..until that level of stress is reduced.

 Photo period ( optimal growth / flowering period being influenced by day length for example ) can influence things as well..  Some Morning Glories may grow while it is hot, but, " optimal " flowering only occurs when nights start to grow longer..  There are at least a couple " tree "- sized Ipomoea sps in Mexico  that only flower in mid/ late December - maybe the start of Feb. 

Other stuff responds to the opposite  ...Nights growing shorter.  IE: Many things that grow / flower in the summer.  

Other stuff, particularly if it originates close to the Equator / lower elevation areas in this region,  may grow year round  -if the temperature profile doesn't stray too far outside of the " comfortable " range they evolved in.

These are the things that would stress more easily in places where there is lots of variance in daily / seasonal / yearly temps.  Oddly enough,  the same would occur if trying to grow some stuff  from really high latitudes ..IE: trying to grow true alpine plants outdoors here, in S. Cal.  ..and/or in FL.  Think you can?  Foa' ghett  'about  it.

Some stuff pushes growth / flowers in response to other cues also ..A pulse of heavy rain / period higher humidity..  Texas " Sage " / Leucophyllum for example.





 

A lot a great info here. Adding to that, it really is a simple process that gets interrupted by the decreased levels of heat. Certainly noticeable for the tropical and semi-tropical palms we love to grow here in SoCal. The palm tree gets water through the roots via osmosis. Using capillary action, the water and dissolved nutrients will travel up the xylem to the leaves. All this is needed to feed the tree for photosynthesis. Water exits the leaves via transpiration. This process works fast in the heat, and much slower in cooler weather. It’s why you see palm growing seasons in cooler climates, but growth is practically year-round in tropical climates. It’s also why in winter, most granular fertilizers are a waste here in SoCal as the plant simply can’t take them up. I hate the yellowing and brown tipping my palms get in the winter, but it gives me a break from year-round gardening as a positive.