Heating Cables

[Scott Stelmar]

Hello All,

Has anybody had experience with burying underfloor heating cables to keep the soil warm around the base of palms where temperatures drop below the cold limit?

I'm assuming that the palm will by natural rising heat, convection, and capillary action keep the crownshaft from fatal cooling.

I'm living in Ocala, Florida and would like to put some royals and Christmas palms in my yard.

 

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[PalmatierMeg]

The soil in most of FL does not freeze and likely doesn’t get cold enough to need heating. Burying under floor heating cables in soil will not provide enough ambient heat to prevent cold damage to anything larger than a tiny seedling. No way will cables prevent freeze damage/death to the crown of a palm (much less warm a 30’ royal). You need to research ways people on PalmTalk protect their palms, i.e., frost cloth, fleece, strings of lights, heaters. You will need to protect Roystoneas and, esp, Adonidias in your part of FL.

And since winter starts in a few days, you should postpone planting your palms until spring.

[Scott Stelmar]

Hi Meg,

Comment noted, but I disagree with your adamant conclusion. For one thing I'm not worried about ground freeze. I'm an engineer who grew up in San Diego as the son of a rare plant collector where we tried different methods that some may have called unprecedented. This is how knowledge is generated and not just passed along as gospel. I've also seen tender plants thrive in areas that are not suitable from an atmospheric environmental perspective but did have geothermal heat which changed the rules.

I didn't expect much of an answer from this group, so I will try my own experiments if nobody has actually tried it.

[PlantDad]

2 hours ago, Scott Stelmar said:

Hi Meg,

Comment noted, but I disagree with your adamant conclusion. For one thing I'm not worried about ground freeze. I'm an engineer who grew up in San Diego as the son of a rare plant collector where we tried different methods that some may have called unprecedented. This is how knowledge is generated and not just passed along as gospel. I've also seen tender plants thrive in areas that are not suitable from an atmospheric environmental perspective but did have geothermal heat which changed the rules.

I didn't expect much of an answer from this group, so I will try my own experiments if nobody has actually tried it.

Whether you are using heating cables or Christmas lights I would strongly suggest covering the palm with a frost cloth or something to hold in the heat. Without something a lot of the heat emitted would quickly escape and be lost.

[ZPalms]

50 minutes ago, PlantDad said:

Whether you are using heating cables or Christmas lights I would strongly suggest covering the palm with a frost cloth or something to hold in the heat. Without something a lot of the heat emitted would quickly escape and be lost.

I have my banana tree wrapped in only Christmas lights, would I benefit from forest cloth then put Christmas lights over to protect the stem?

[Las Palmas Norte]

5 hours ago, Scott Stelmar said:

I didn't expect much of an answer from this group, so I will try my own experiments if nobody has actually tried it.

Seems like you had your mind made up before you posed your question. If you "didn't expect much of an answer from this group" why bother?

[Scott Stelmar]

I guess this is like many tests where people rush ahead to offer opinions without reading the question first:
I wrote "Has anybody had experience with burying underfloor heating cables" and got classic elitist advice. 

If you have information regarding the subject, please respond.

P.S. I found this article informative regarding post-freeze treatment.
ENH-92/MG318: Cold Damage on Palms (ufl.edu)

Edited December 19, 2022 by Scott Stelmar

[PalmatierMeg]

You ask (mostly) non-engineers for engineering advice? Actually, my first thought was, “Who in the world buries underfloor heating cables underground in FL?” Given all the rain, potential flooding? A new way to electrocute nematodes and grow Trachycarpus? To thaw ground that never freezes? To electrocute prowlers in your yard?

I’d like to see photos and a plan/sketch of your proposed project and a treatise on what/how it might work to warm above ground air to protect a $50 Christmas palm, i.e., Adonidia merrillii in official palm-speak. Obviously I need to be enlightened as I am a non-engineer (although I love Dilbert).

[Allen]

I wasn't going to jump in but here we go...  No I haven't buried this type of cable and have never heard of anyone doing so.  

From a practical perspective are you going to bury 240 feet of cable?   It also looks like you will need to weatherproof the controller.

Are you going to be able to deal with leaving the cable in the ground once roots, etc grow over it.  It will be really hard to remove.  

Are you going to place it where you don't have to dig and risk cutting in the future?

As for heating palm crown area----I don't think it would have any meaningful heating action more than a foot or 2 above the ground if cable is buried in the ground.  A heat source wrapped around the palm and then a wrapping over that is appropriate for that purpose.

[Scott Stelmar]

Hi Meg,

So, the problem may be described via a steady state heat transfer problem where you calculate an approximation of the bulk film coefficient of the plant surface and solve for a heat input required at ground level, versus a convection value of a worst-case weather scenario, (temperature, humidity, wind velocity) to achieve a desired meristem temperature safely above freezing. 
The meristem can be roughly considered a fluid volume that also experiences convection within the tissues. The mature leaves are likely sacrificial, but the palm should survive.

Warming the above ground air is not the goal, protecting the growth point is.
I would wrap the coils around the bulb and rhizosphere as shown in the illustration.

I find your curiosity engaging, seek to know all things as the renaissance masters showed us.

Scott

[PalmatierMeg]

Ah, a science experiment. I applaud it. And, babble-jargon aside, I get it, certainly as an intellectual exercise. Would I suggest you do it to protect dime-a-dozen weedy Roystoneas and Adonidias? Uh, no and no. Your plan would require digging multi-level trenches all around and under the footballs of palms, then laying yards of cable. Palms, in general and in particular, resent having their root systems dug and hacked, the same roots intended to transmit heat up through the trunk to warm the meristem in frigid weather. Biologically, would that even work? I have a basic grasp of thermal issues but not enough knowledge to say categorically. Offhand, I would say no. Howling north winds present huge obstacles to tropical palm survival without direct application supplemental heat and layers of flannel and fleece. And the labor and economical aspects of burying heating cable underground far outweigh any benefit of saving otherwise cheap and plentiful palms.

I once pondered what I could do to grow two “impossible in FL” palm species: Dictyocaryum lamarckianum and (my impossible dream palm) Lepidorrhachis mooreana, not to mention Juania australis and Hedyscepe canteburyana. All of them require a narrow range of cool/chilly temperatures and will promptly keel over dead in FL heat and humidity. If money were no object, I envisioned constructing a climate controlled “cool conservatory” a couple or three stories tall where these palms would live in a/c comfort. Aside from the nutty idea I could actually pull off my idea, money was a big object as I am not related to Elon Musk.
”

[Las Palmas Norte]

21 minutes ago, PalmatierMeg said:

... Aside from the nutty idea I could actually pull off my idea, money was a big object as I am not related to Elon Musk.

"Nutty" and "Elon Musk" in the same sentence? I like it.😁

[Scott Stelmar]

Meg,

It is indeed a thought experiment at this point, but entertaining nonetheless.
I have some Juania seeds that I planted, and now that you mention it, putting cooling coils in the ground to keep their tootsies cool would be a similar project.

I actually envisioned preparing the bed first with the appropriate cables and then planting young palms.

The Adonidias I have now are planted in half whiskey barrels on roller platforms and are residing in the house for the remainder of the winter, but as I just got back from Antigua, I see that they can grow to a respectable height. A long-term solution is needed and the sooner I start the better.

I loved the clumps of triple Kings I grew in San Diego, but understand they are also unlikely to survive here without extreme measures.

Happy growing.

Edited December 19, 2022 by Scott Stelmar

[PalmatierMeg]

1 hour ago, Las Palmas Norte said:

"Nutty" and "Elon Musk" in the same sentence? I like it.😁

Well, in that case maybe Elon and I are closer than I thought. Difference is, he could pull it off.

[Will Simpson]

Mulching heavily is one way I keep soil temperatures up here  .

Will

[PalmatierMeg]

Scott, Juania australis has the dubious distinction of being the most difficult palm in the world to grow, according to true palm scholars. I don’t think even a/c cables could help them here.

And I agree: the king palms, i.e., Archonotophoenix are no-go in Ocala. You might consider moving further south. Or reconsider the typical new palm grower’s bias toward pinnate palms, esp. crownshafted ones and against hardier palmate/fan palms. Crownshafted palms tend toward exclusively tropical. Exceptions are a few species of Chamaedorea, i.e., microspadix, radicalis. The queen palm is a Class II invasive in FL. Butias such as the pinto palm are better candidates for your location. Better yet are the many Sabals, Bismarckia, Chamaerops.

[Scott Stelmar]

Yuck to all you mentioned except the Chameadoreas, especially the metallica.

I just installed two 20' queens two months ago and they are settling in nicely. 

[RJ]

There was a guy in Europe who had a large CIDP way out of its zone he heated the ground under it with heated water pipes IIRC. No idea if it’s still around and I read about it several years ago.  Ought be worth a google search …

Edited December 19, 2022 by RJ

[akaranus]

so far so good, but also heating above..i am kind borderline for biizzie and i think heating roots its the key for long cool wet period, btw i am  electrical engeenieer  

 

 

Edited December 19, 2022 by akaranus

[akaranus]

my plan is give enough time for bizzie( few yrs) untill roots gets deeper part of soil where soil/water is warmer, about 13°C all the time bellow 1m deep , and plant will be bigger to better amortize eventually cold snaps...

[Scott Stelmar]

Akaranus,

Excellent. I'll be delighted if you keep me posted.

All great exploration must begin somewhere, and it looks like we are on the same track.

[PlantDad]

23 hours ago, ZPalms said:

I have my banana tree wrapped in only Christmas lights, would I benefit from forest cloth then put Christmas lights over to protect the stem?

I would definitely cover them with frost cloth also as it will hold in the heat emitted by the lights so its not lost. I'm not sure if lights on the outside of the frost cloth would help a lot as there is nothing to contain the heat from the lights so a lot of the heat would likely still be lost. Maybe instead of putting one strand of lights on the outside and one on the inside of the frost cloth just put both on the inside as it would be much more effective at providing and holding more heat more efficiently than if the lights were outside of a frost cloth and uncovered. I honestly don't see just wrapping a palm or banana stem in lights without anything such as frost cloth to cover and hold in the heat being very effective at keeping the plant warmer as heat quickly rises and is lost when there isn't something to insulate and hold it in.

 

Edited December 20, 2022 by PlantDad

[Hortulanus]

21 hours ago, RJ said:

There was a guy in Europe who had a large CIDP way out of its zone he heated the ground under it with heated water pipes IIRC. No idea if it’s still around and I read about it several years ago.  Ought be worth a google search …

Was this the guy in the Alps or lower Alps somewhere who built a scaffold around it?

[Hortulanus]

I don't know about Florida conditions but from what I've read in this forum so far. Nowhere in this area the ground gets as cold. I've worked with heating cables in the worst cold snaps that happen every 10 to 15 years and what I can tell about heating cables is that you should wrap them properly around the palm. Preferably not diretcly onto the plant but with a fleece cloth underdeath. But this depends on how cold it gets in the respective area. Here even in the coldest of blasts the heating cable can be too hot directly on the plant. What I also did is I always wrapped the cable around the bottom and in 2-3 circles on the ground to prevent cold getting to the roots at least from above. The I put some mulch over it (if not alrady present) and another fleece cloth or 2 over it to insulate the warmth. Putting heating cables into the ground permanently doesn't seem plausible to me. It would probably work to some extend if you would lay out meters of cables in a net-pattern all over you garden. But they would eventually get a malfunction because they deteriorate just in a couple of years and then you would have to digg them out. Plus they are never that cheap.

[ZPalms]

17 hours ago, PlantDad said:

I would definitely cover them with frost cloth also as it will hold in the heat emitted by the lights so its not lost. I'm not sure if lights on the outside of the frost cloth would help a lot as there is nothing to contain the heat from the lights so a lot of the heat would likely still be lost. Maybe instead of putting one strand of lights on the outside and one on the inside of the frost cloth just put both on the inside as it would be much more effective at providing and holding more heat more efficiently than if the lights were outside of a frost cloth and uncovered. I honestly don't see just wrapping a palm or banana stem in lights without anything such as frost cloth to cover and hold in the heat being very effective at keeping the plant warmer as heat quickly rises and is lost when there isn't something to insulate and hold it in.

 

I do have my banana covered in a box but I’ll get some frost cloth and wrap the tree so the lights are covered! Thank you much appreciated! 🤠

Edited December 20, 2022 by ZPalms

[PlantDad]

On 12/20/2022 at 1:42 PM, ZPalms said:

I do have my banana covered in a box but I’ll get some frost cloth and wrap the tree so the lights are covered! Thank you much appreciated! 🤠

No problem😃

[akaranus]

On 12/20/2022 at 12:47 AM, Scott Stelmar said:

Akaranus,

Excellent. I'll be delighted if you keep me posted.

All great exploration must begin somewhere, and it looks like we are on the same track.

for now everthing looks great, we are coming out of winter and bigger bismarck is in perfect shape, smaller have some minor spots on leaves but it is also ok...

i was turning on cabels during night time only when temps droped bellow 6°C...bigger is also opening new leaf, and smaller is showing spear growth...

[Allen]

5 minutes ago, akaranus said:

for now everthing looks great, we are coming out of winter and bigger bismarck is in perfect shape, smaller have some minor spots on leaves but it is also ok...

i was turning on cabels during night time only when temps droped bellow 6°C...bigger is also opening new leaf, and smaller is showing spear growth...

 

I get a malware warning trying to go to your website.  But palm looks great!

Edited February 21 by Allen

[akaranus]

Just now, Allen said:

I get a malware warning trying to go to your website

oh..that site is turned of...must remove link...

[D Palm]

I have used heating cables for a Royal Palm about 6’ tall no trunk yet.. On the ground and wrapped. The palm died. I tried it this year on a bangalow palm, on the ground and covered with a blanket. It shared the blanket with a orange BoP that is unscatched. The palm crown completely detached from the small trunk today.
 

Ebery time I have used heating cables the crownshafted palms have died. I will never use heating cables again except for water pipes. These were made to stop pipes from freezing, not palms from getting torched in out of zone climates.

Good luck to anyone else. 

[SeanK]

On 12/19/2022 at 10:53 AM, Scott Stelmar said:

Hi Meg,

So, the problem may be described via a steady state heat transfer problem where you calculate an approximation of the bulk film coefficient of the plant surface and solve for a heat input required at ground level, versus a convection value of a worst-case weather scenario, (temperature, humidity, wind velocity) to achieve a desired meristem temperature safely above freezing. 
The meristem can be roughly considered a fluid volume that also experiences convection within the tissues. The mature leaves are likely sacrificial, but the palm should survive.

Warming the above ground air is not the goal, protecting the growth point is.
I would wrap the coils around the bulb and rhizosphere as shown in the illustration.

I find your curiosity engaging, seek to know all things as the renaissance masters showed us.

Scott

Your project requires quite a bit of calculation. You need to know the thermal conductivity of the soil. You need to know how much water is trapped in the soil, which can change by the hour. What is the power rating of the cable. Then, all will be lost in a breeze as the localized warm air is replace by cold.

If you want to be successful, excavate the garden and run copper piping about 8" below the surface, on a closed loop running through a boiler. Then plant your palms.