Wow that's very interesting. I guess I should really water my plants a lot more after seeing this even though our temps are not as hot as yours... but still I am way under watering my guys.

Thanks for doing this.

Hey kms2,
try to make some measurements at 3:00 p.m. The temperatures will shock you!

George

I was thinking of using a meat thermometer and testing the temp down where the roots are.

I'm not surprised it's very hot on the surface, but down about an inch or two and especially around the inside perimeter of the pot is where the roots are. The black pastic pots are going to really absorb that heat.

Your cuttings look like they're in full sun to me. Are you saying they get a few hours of shade?

Dave,
I did measure an inch down. it was about 20 degrees cooler. Mulch also took about 20 degrees off the temp. I get the black pot thing or in this case green pots but they are not in black pots. Terra cotta or, green plastic pots, or clear bottles for the perlite and gritty mix.

if you look in the top quarter of the picture showing all the cuttings you can see the shadow from an overhead poly-carbonate structure being cast right about on the bags of mulch and perlite. As the sun moves west the sun angles under the overhead poly-carbonate. You can see in my "after watering" pictures the area is in part shade again. Which was probably a half hour to 45 minutes later. They get maybe 3 -4 hours of mostly diffused light.

Important to note water out of the hose bib was 82 degrees. So i guess the evaporative process would be the reason why the 2nd reading temps were even lower.

George, it was at about 1530pm.

I don't have a thermometer on hand to use, but when I went outside I was shocked to see the leaves on my "mystery " cutting were hanging straight down, and were wilted, obviously my plant isn't happy in the 107 deg. heat. I moved the pot into filtered shade, it was hot to the touch.
Thanks for bringing up the subject of soil temps, Kms2!

I get about the same temps with my digital meat thermometer. I have painted many pots with or ran and it helps tremendously.
I wonder ate what point it is actually harmful to their roots. I imagine above 110 120 is no good for them.

Mike

Hi K,

Very interesting ...

Lots of interesting readings and then seeing how the temps were reduced was fascinating..

The heat of the day does have an effect on all soil mixes! You proved that!!!

I also find it even more interesting that they can handle these temps that are higher than I ever expected. So it goes to show how these trees can adapt to lots of mixes and soil types. Think of all of the places that they grow.. Florida in full sun .. Hawaii in full sun, but with the great rain in the afternoons.. California in the heat of the day, without those afternoon rains...

This was very interesting and I thank you for taking the time to check the temps... I see something that I sent ? Looks like it is doing well? ;-).

I noticed that you have a few bottles with cuttings... Could I make a suggestion? If I were you, I would add mix to the top of the clear bottles to protect the stem from the burn they may receive. I wouldn't allow any plastic to allow the sun to magnify on the stem. I have made this mistake and I fill to the top of the container. Just my 2 cents!!!

Great thread.. Thanks for the info!!!

I also believe in watering frequently in the summer especially if you don't have the afternoon rains. The trees will give you a hint, but you want to water before they get to that point. I will say, that some of my trees have been more thirsty than others.. Divine is one. The other is my Kapalua !!
It seems that every other day, I have to water this thirsty beauty!! Since it is a large tree and lots of foliage, it is needing more water than the others. He seems to need my attention and he gets it!!! Lol. I look at him in the am and I check on him in the evening. I guess I will pot him up into a larger container after he blooms. I don't want to disturb him at all..

They love water..especially when we live in the south and in the hot climates. We need to give them water and watch them. If they are in a good fast draining mix ( which ever you choose ) they will dry out.. ( which is good...) They need water in the summer!!!!

Thanks K!

Take care,

Laura

We are under water restrictions, Monday and Thursdays only. So frequent watering is not an option. I use black plastic pots only for rooting, those are on the front porch where they get about 4hours of am sun per day. I use potting soil and heavily mulch the plants. This week I started moving plants off the porch roof to the side yard, they will still get full sun but will not be on the black tar roof and will be cooler. They will get pm sun, not almost full day sun.
The plants in the garden are bunched together and stuck among other plants to shade the pots/roots, thus lessening water loss. I`ve planted most of the seedlings and heavily mulched around them.

The hot temps are great for rooting! Time to order cuttings.
Tally Ho!

Reading all here I understand why we need to mulch. My cycads (most of them Encephalartos) are mulched and are doing just fine. After my first plumeria was under attack by spider mites, I was told to get rid of the mulch which I did. Now, that is so hot, should I mulch her pot again? I also have a few rooted or rooting. What about mulching those?
Thanks for any advice.

Mima

That's some extreme temps, I mean I knew the soil must get warm, but seeing it really brings it home. I wonder how hot my pots get being on a wooden deck that gets so hot I can't go barefoot...

Geez, that is super-hot! Interesting how some mixes seem hotter than others. Thanks for the added info, K, it's very useful to know.

I just went outside to double-pot some more stuff, and plunge anything in black pots not already plunged. When I checked the "nursery" with all my seedlings crowded together in black pots, they weren't anywhere near as hot as I expected. The shade from all their combined foliage is keeping the bases cooler. Whew!

Unglazed terracotta pots are cooler, too, than the glazed ones.

I find it quite interesting how just a little bit of water was able to drop the temps no matter what mix by about 40 degrees. it seemed a layer of mulch had a 20 degree difference and an inch deep in the soil had another 20 degree of difference.

I set up to do the test again on Sunday and it was fantastic see my experiment interrupted by storms. There will be plenty of other days to try it again.

Laura,
its wrinked but leafing out but still dont see any roots I am double potting it to give it a bit more insulation from that kind of heat.

Those temps are bad kms2! I have noticed some of my trees in black pots and gritty mix feel like they are baking! Yes, Plumerias grow in the tropics and it's hot BUT they are in the ground. Their roots are cool. Their heads can take full sun all day long but they like their roots cool. Also in most of the tropics there are breezes that help to keep leaf and temps down.

I have grown them both ways for years, there isn't a doubt in my mind, they do better planted in the ground. However, let me say this... if they are young, small trees or rooted cuttings, I suggest leaving them in pots until they get bigger and have a well developed root system if you have to move them inside in the winter. In.South Florida or the Keys, put them in the ground and leave them alone and watch them take off.
I have a Lutea that was being a real pain. It's a tall and skinny ugly stick that was that way when it was sent to me and it has never bloomed. After I took it out of the ground last October and wintered it in a pot in the garage, this spring I could not get it to do anything. No claws, then claws, claws would shrivel up. I repotted it in gritty along with all the others. couple of months later, still no leaves. I took it out of the mix, a couple 1" tiny brown roots.

I was over it. I stuck it in the ground by some that are in pots and told it to root or die, I didn't care which it did. It sat there doing nothing for a couple of weeks and I waited to see if it rotted. Suddenly it took off, leaves all over the place, which means it also is rooting. I gave it some Root Excelerator to help the roots keep growing. No heat mat needed, The ground provides heat without the stress of wild temp swings which occur in pots.

I believe bigger trees need to be in the ground and do far better by planting them in the spring, lifting them in the fall if you must due to freezes. Put them in a pot with the soil they were in while planted, put them in garage, greenhouse, whatever you use and leave them alone until spring. On warm days you can mist or give a cup or so of water, but keep them dry.

Each year they will get much bigger than they would in pots.

I have white plastic trash bags around some of mine in pots that get morning to early afternoon sun at a brutal angle. The heat of those black pots filled with gritty is insane down here in FL. The white bags reflect the heat and make a huge difference!

We have had so much rain, day after day, LOTS of rain. I have about 100 in Al's mix and have yet to have 1 rot. In fact I have never seen such explosive root growth and such healthy roots on potted plumies. They are coming out of the bottom, all over the top, even ones that were just rooted in April have filled 1 gallon pots and are read to move up. Roots seem to love the gritty mix but you do need to get those temps down on the pots or the roots near the pots outer sides fry and turn brown. It's easy to test this. Put one where it gets sun, don't turn it. Take it out in a couple of weeks and check. All the roots on the inside that faces the sun will be in bad shape, the ones on the backside, perfect. Once I discovered this I moved most of them so the angle of the sun wasn't as bad, the others that get that intense angle from 9 Am to 2 pm I wrapped with white plastic to reflect the heat. It works,leave the bags loose so the black pot doesn't show through if the bags are thin.

My trees look great, growing well, not many blooms yet. They are recuperating from the moves and repots I imagine. I may get mostly roots and growth this year but that's ok. With healthy plants and a big healthy root system, the booms will come in time.

My Kapalua has an inflo. Hopefully all this rain won't cause the buds to drop off.

Powderpuff...is yours the REAL Kapalua? BIG on my wish list...any other place to order and be sure than Exotic? roxanne

Laura, I agree, Divine is a hug water hog. I don't think it's possible to over water it but if underwatere, it's leaves get curled and funky looking,

So that is true about Divine, powderpuff?
I got a JJ Divine recently and I need to water it the most as per the moisture meter. It's unbelievable how much water for such a small plant. My others don't get that much water. So i decided to let her a bit dryer, being afraid i'd overwater her. But I noticed the leaves get indeed a funky look, and i didn't know why. Interesting... maybe she's in a growth spurt... pushing new leaves out every day since I got her. I was first thinking that the soil mix is not holding the water enough but now, reading this, I think it might be the same reason here too.

Mima

does the meter have a probe or are you just reading reflected heat? If you are reading reflected heat, you should take your plant out of the sun into the shade and then read. Your perlite is white so it reflects most of the light into the meter. This may not actually indicate the surface temperature. Out of direct light, your meter will begin to read radiated heat. Just a thought.

The Aggies did a study a few years back on temps and plants, at a certain temp plants quit absorbing water, kind of a summer dormancy. Somewhere in the back of my brain is that information.

The Aggies also spent who knows how much money and time developing a maroon carrot. Wild carrots, the forefathers of our familiar orange carrots, were maroon.
Tally HO!

Tally they also developed the maroon bluebonnet, its not as hardy as the blue. I tried maroon one year, they did not reseed like the blue. Barbra

Bill,
There is some sort of compensator for reflected light waves which with the exception of highly reflective surfaces reduces inaccurate readings.

My readings with a probe and the IR thermometer found it to be quite accurate. It was interesting but not surprising to find the variance between the surface and the approximate center mass of the soil was minimal in anything smaller than two gallons. at the two gallon mark there was that 20 degree difference again. And in one instance the surface was cooler than the inside. Perhaps due to evaporation?

IMO A great reason to go as big as you can on containers.

Tally, it would be interesting to see where the danger zone starts.

kms, my guess would be that all of those root temps were if not in the danger zone, were surely in the stress zone and yes, the Gritty gets very hot. Some plants don't seem to mind hot roots, I do not think Plumerias are one of them. Trees in white pots or white 5 gallon buckets with holes drilled in them ALWAYS look better than the ones in black pots, at least here in Florida. I only have to look at my trees and compare the ones in the ground to the ones in pots to know where they really want their roots to be.

I think the grit is what makes it hot. It's granite. Granite gets hot and cold and takes a long time to heat up or cool down. No different than the granite on my kitchen counter tops. I could be totally wrong, but that's my guess. It's not so much the heat from the top that is bad, at least not here, it's the blistering heat that hits the sides of black pots. I had a gray top on today and lasted 10 minutes before I was roasting. Came inside, put on a light yellow top, went back out and was fine. light pink, yellow, white=cool, gray, navy, BLACK=roasting alive in FL in the summer.

I firmly believe Plumerias grown in black pots in Florida will never do that well. They will try to live and often do, but they are struggling. Cool roots, they are happy... UNLESS rooting a cutting, then heat is good.

sago... yes, Divine is a huge water hog. As long as it's well rooted, it's almost impossible to over water it. Thumbelina likes a lot of water too. I need to make a list of my water hogs, there are quite a few.

Yes, it's the real Kapalua and I got it from EP and paid a pretty penny for it, 7 tips, beautifully shaped tree, nice and compact. It's my most expensive and I worry about it all of the time. Sometimes I wonder if it isn't easier to just collect the old reliable ones and enjoy them with no worries. :P

I think it is hard to feed them in the gritty mix. I feel they aren't getting enough because it runs through so fast and the ones I do have in soil look better, greener, healthier. However the roots are fabulous in the gritty mix.

I'm not taking them out of it this year, but next spring I am going to put some of them back in soil and compare. Divine and Thumbelina for sure. They do not like the Gritty mix, no question about it. Some seem to love it, others not so much.