Protecting Washingtonia in zone 7a without electricity

[Palmlex 20]

Hello everyone,

I've put a Washingtonia Robusta (Filibusta maybe?) in the ground this year, in zone 7a (if using the average annual extreme minimum temperature, which is around 7F/-14C). The issue with my location is that while most winters it's a solid zone 7b (last winter was actually a zone 8a), every few years (5-10), a seriously cold front can get here and plummet temperatures way below that. -9F/-23C is the lowest I've personally experienced, but I didn't have anything to actually measure it at the time, so I just have to trust the temperature at that time's forecast.

As you might have already figured out, -9F/-23C is pretty much zone 6a temperatures, almost 5b, so the temperature swings here can be pretty drastic from one year to the other.

To get to the point, I have a Washingtonia that I have already covered (too soon, but I want to be as sure as possible that I'm able to protect it) in the ground that looks gorgeous for its first year, at about 4ft/1.2m height for the tallest frond. Its current protection consists of 3 walls of 100mm (4'') thick polystyrene sheets and a 10mm (0.4'') thick twin wall polycarbonate window on the south side.

After having done this, I noticed the night time temperatures inside were almost the same as outside. So to try to help it store some of the sun's heat, which is actually too much, since the enclosure can easily surpass 102F/39C on a 42F/6C day (ask me how I know), I've also added black containers filled with around 27 gal/100L of water around the palm. I was hoping the water would tone down the daytime temperatures too, but I still have to ventilate it so I don't cook it. At night, the water seems to help somewhat. So far, what I can tell is that at 32F/0C, the water keeps the enclosure at around 40F/4.5C and I'm expecting it to make an even greater difference when it's colder outside.

The issue is I'm not expecting this to be good enough if we get another freak 6a/5b winter and heating it electrically is a serious no-go for me since the place is full of mice and other critters and I really don't feel safe doing that. I was thinking I could add hot water in some of the containers before one of those really cold nights, but I'm not sure that would be enough and it would also be a lot of work to carry around lots of hot water to it every day when one of these cold fronts hit (especially if the water freezes in the containers, that would be a nightmare).

Does anyone have any tips and tricks on how I could insulate or warm up this palm better that doesn't involve doing anything that could be dangerous (like a shock or fire hazard)?

Thanks so much for reading and I hope you guys out there in zone 9+ love your palms and appreciate how much easier it is to have them around. 

[Will Simpson 817]

I protect my  Filibusta TRUNK  anytime I see anything below 16F with Xmas lights wrapped around the trunk and a layer of blankets over them . I have to put up with ugly damaged FRONDS below 24F , but it puts out 25 fronds a season so it looks decent by May . 

If your trunk is short you could put a collar around the trunk and fill in around  it with mulch maybe 1.5 to 2 feet thick around the trunk . After the cold has passed remove the mulch away from the trunk , leaving it near in  case you have to reapply it . Mulch high up on Bananas and other herbaceous plants can keep their trunks   from freezing . 

I don't know your location but I like to keep my Washy trunk above 15F . 

Will

Edited December 4, 2021 by Will Simpson

[Will Simpson 817]

The collar that I mentioned could be   a large  plastic trash can with the bottom cut out . Put it over the palm and fill it with mulch covering the entire trunk  .  Cover the sides of the trunk by a couple feet of mulch  and a foot above the trunk . Leave it on for a few days until the below 15F weather has passed and then dig out the trunk , but be ready for the next blast . It sounds like you may need to do this procedure several times in a winter . 

That protection method doesn't protect the fronds or petioles that are outside of the warming  effect of the mulch , so plan on ugly fronds until new ones grow in .

You could throw leaves heavily over the whole palm too . That would save the fronds . Take chicken wire and make a collar to hold in the leaves ,  and fill up the area around the trunk and fronds by several feet . Leaves tend to compost down so have a lot available for the whole winter . The leaves could be left on longer than mulch too . 

Remember that as fast as Washys grow ,  it's just a matter of time before you will need  supplemental heat . I mean ,  how am I going to protect my Washy without supplemental heat on those nights below 15F with 20' of trunk  lol ?

Those are the only ways  I can think of where you wouldn't  have to use supplemental heat at least until it got so big you had to 

Good luck ,

Will

 

Edited December 4, 2021 by Will Simpson

[Palmlex 20]

The mulch idea doesn't sound bad, apart from the fact that I don't have any mulch on hand. As for the future, I was thinking I could maybe find a way of providing heat using low voltage DC current (so I don't have to worry about people being around it), but the selection of bulbs for this application is quite sparse, since most of them are LED and put out like 1W per feet.

How much power do you think your Xmas lights put out?

[Allen 1,272]

1 hour ago, Palmlex said:

The mulch idea doesn't sound bad, apart from the fact that I don't have any mulch on hand. As for the future, I was thinking I could maybe find a way of providing heat using low voltage DC current (so I don't have to worry about people being around it), but the selection of bulbs for this application is quite sparse, since most of them are LED and put out like 1W per feet.

How much power do you think your Xmas lights put out?

You won't be able to protect the palm that way.  You need to think in the order of 10W per foot of height if the palm is wrapped directly over that heat (ie. mini Christmas lights or heat cable).  Without electricity your palm will die once it gets bigger.  Small under 6 feet of height, wrap the palm in burlap, take a fence tall enough to circle it in approx 20-25" diameter, fill with dry leaves and cover.   If it gets real cold it may still die.  

[Allen 1,272]

3 hours ago, Palmlex said:

To get to the point, I have a Washingtonia that I have already covered (too soon, but I want to be as sure as possible that I'm able to protect it) in the ground that looks gorgeous for its first year, at about 4ft/1.2m height for the tallest frond. Its current protection consists of 3 walls of 100mm (4'') thick polystyrene sheets and a 10mm (0.4'') thick twin wall polycarbonate window on the south side.

After having done this, I noticed the night time temperatures inside were almost the same as outside. So to try to help it store some of the sun's heat, which is actually too much, since the enclosure can easily surpass 102F/39C on a 42F/6C day (ask me how I know), I've also added black containers filled with around 27 gal/100L of water around the palm. I was hoping the water would tone down the daytime temperatures too, but I still have to ventilate it so I don't cook it. At night, the water seems to help somewhat. So far, what I can tell is that at 32F/0C, the water keeps the enclosure at around 40F/4.5C and I'm expecting it to make an even greater difference when it's colder outside.

The issue is I'm not expecting this to be good enough if we get another freak 6a/5b winter and heating it electrically is a serious no-go for me since the place is full of mice and other critters and I really don't feel safe doing that. I was thinking I could add hot water in some of the containers before one of those really cold nights, but I'm not sure that would be enough and it would also be a lot of work to carry around lots of hot water to it every day when one of these cold fronts hit (especially if the water freezes in the containers, that would be a nightmare).

Does anyone have any tips and tricks on how I could insulate or warm up this palm better that doesn't involve doing anything that could be dangerous (like a shock or fire hazard)?

Thanks so much for reading and I hope you guys out there in zone 9+ love your palms and appreciate how much easier it is to have them around. 

The polycarbonate sheet and a sealed box is a problem.  Just put all sides in foamboard.  As far as electricity being dangerous, most outside plugs have gfci protection which will trip the electric off instantly if there is any stray current getting loose.  if the plug does not have this already you can buy a gfci extension cord cheap on Amazon.  In the box put a 35/45 thermocube and hook up either a couple 40-60 watt Fluorescent bulbs or a string of 5-10 C7-C9 lights hanging loosely within box.  Just get 50-80 watts in there and monitor temps with a wireless thermometer.

[Jimhardy 653]

The high temps never seem to hurt my Washy when I was growing one...

it was once 117F in the enclosure and the palm was unfazed (surprisingly).

Maybe the water containers don't need to be black if its that warm in there...

you could always put a little shade on the top so the sun hits more or the water

and less of the palms leaves. as far as protecting it without electricity I would

say insulation, insulation,insulation along with your water containers.

[DreaminAboutPalms 397]

Build a teepee. Get three 8 foot long poles or stakes, zip tie at top, and throw a tarp over it

[Jimhardy 653]

I like the Teepee idea!

All we need is for the palms to cooperate and grow their leaves out at the bottom. 

[maskedmole 54]

I think the biggest enemy of this palm tree is wetness combined with cold. I think if it could avoid any moisture for those about 4 winter months it would be happy. The problem with this palm is it eventually it grows very tall, too tall to deal with easily and it does so fast. If you could somehow lean the palm tree and make it grow sideways several feet, it would be much easier to deal with. Then you could just build a structure over it every winter with like some posts and plastic panels to keep moisture out and under it you could use oak leaves and then blankets when it got very cold. Dig a huge hole about 15 feet down and grow it in that and just cover the hole with a plastic sheet in winter haha but then you might need ventilation. Well just put a sloped roof over the hole and leave the sides open. Just kidding that is probably a bad idea. I mean it might flood unless it was very well draining.

Edited December 6, 2021 by maskedmole

[Palmlex 20]

I doubt this palm could survive in zone 7 or lower just with insulation and no form of extra heat. I've used almost the thickest polystyrene sheets I could find at 4'', which are actually used to insulate houses and before adding some water mass inside, the temperature inside would just match the outside temperature once the sun set.

Even with the 27 gal/100L of water I've added, after 2 cool overcast days, the temperature inside is only around 4F/2C higher than outside.

Edited December 6, 2021 by Palmlex

[Allen 1,272]

3 hours ago, Palmlex said:

I doubt this palm could survive in zone 7 or lower just with insulation and no form of extra heat. I've used almost the thickest polystyrene sheets I could find at 4'', which are actually used to insulate houses and before adding some water mass inside, the temperature inside would just match the outside temperature once the sun set.

Even with the 27 gal/100L of water I've added, after 2 cool overcast days, the temperature inside is only around 4F/2C higher than outside.

Palms do not put out heat so boxes or covers without heat only keep the palm dry and keep frost/snow/ice off the palm with slightly higher temps. 

To fix all this, replace clear sheet with foamboard (You don't want light in there to grow palm anyway and the crazy fluctuating temps are not good), then run a extension cord, plug in a 35/45 thermocube and hang on a pole near spear of palm and plug in the stuff linked below anywhere in box.

Qty (2) incase one bulb goes out.  Lowes also has some cheaper plug in cords for these but I couldn't find online if the box stays dry

https://www.lowes.com/pd/BELL-150-Watt-Black-Line-Voltage-Plug-in-Incandescent-Spot-Light/1000404851

Qty (2) incase one bulb goes out

https://www.amazon.com/Compact-Fluorescent-Spiral-Daylight-Equivalent/dp/B072LRBCMF/ref=sr_1_7?keywords=fluorescent%2B100%2Bwatt&qid=1638799994&sr=8-7&th=1

Qty (1)

https://www.amazon.com/Farm-Innovators-TC-3-Thermostatically-Controlled/dp/B0006U2HD2

If mice chew a cord or power gets loose gfci in your outdoor plug or this cord.  Plug this in at outlet and run extension cord off it.

ONLY USE if plug does not have gfci already!

https://www.amazon.com/DEWENWILS-Outdoor-Extension-Splitter-Contractor/dp/B08G4HNCR1/ref=sr_1_5?keywords=gfci+cord&qid=1638799767&sr=8-5

Edited December 6, 2021 by Allen

[Will Simpson 817]

I use this gfci  outlet so I don't worry about electricity outside . It will trip if water is a problem . Usually cold weather down to 15F is dry so I only plug up my protection on those cold dry nights . I unplug it when temperatures moderate and I always will have it unplugged during a rainy event . 

Will

 

 

Edited December 6, 2021 by Will Simpson