You might try a Styrofoam box and throw up dirt around the base of the box. I've never had problems with pests. Of course, I don't believe we have moles. Have you tried bait inside your structures? I have 4 outdoor palms. Here's a picture of a 10' Trachy of mine just getting ready for winter, plus the box I use.

Wow, that is absolutely awesome. Zone 4? Really? May I ask where, and how cold are your winter minimums?

It looks like you're using compact florescent light bulbs in there -- I assume those provide enough heat to keep them ok, as the palm in the photo is spectacular. To me,that seems like a good compromise -- not too expensivev to run, but it obviously still works.

My two windmills are a bit smaller than yours, based on the photo. I'd say the trunk on yours is probably about 12 inches taller than mine.

Do you pack any type of insulating material into the structure around the palms, straw or fiberglass or anything?

As far as the dumb voles go, I've done everything I know of. A few years back, I had a pretty big bed of "hardy" tropicals, about 3 feet wide x 20 feet long, covered with a four foot styrofoam and wood structure (similar to yours), packed with straw and fiberglass. I put $40 worth of mouse poison blocks in there, the voles still ate things, and ate some but not much of the poison bait. They seem to prefer the plants to the poison. I spend about $100 a year on various traps and baits, but still only keep the voles to a dull roar. Guess I should get cats!

Dennis
SE Michigan

Hi Dennis! I have experienced -45 F. temperatures before at my house. Since I started growing palms outside, I have experienced -40 F. (about 7 years ago.) Typically it gets down to -20 to -30 each winter. I add nothing to the boxes as far as insulation. As long as the boxes are well caulked, the light bulbs keep them warm. You'd be how surprised how much heat builds up in these boxes from the light bulbs. When I had 4' boxes, I only had two light bulbs. Once I refurbished them and added another 2' to each box, I decided to add another light. The palms actually appear to be more healthy than ones I have seen of the same type in Los Angeles. They seem to enjoy the cool summers we have in northern Utah.

Kevin

Thanks for the information. This certainly looks like it would work for me. I could see adding a tight layer of tough wire mesh of some kind around the base of this structure to help keep out voles.

My low temps are nowhere nearly as cold as yours. Coldest I've had in the past decade has been about -11 F. Used to get into the -20's in the 1970's, but the area has urbanized a lot, and gotten warmer as a result.

Seeing these in the landscape must really shock people.

I totally agree with you about these palms tolerance of cool temps, they actually seem to love them. My needles and sabal sulk in cool temps, but not windmills.

You're going to need a bigger box there, soon, I'd say.

Dennis
SE Michigan

Hi Dennis. I wish we had your winter temperatures! Since my Trachy grows a foot per year, this year I'm using the 8' box hoisted on top of the railroad ties. Next year, I will probably give up on a bigger box (my wife said I could not build a bigger box. She's embarrased by them now). I will probably try a heating cable with thermostat, and bubble wrap. At least I can use this method no matter how tall the palm gets. Please post some of your pictures.

Kevin

It must be cool to know whats in those boxes during the winter!That is one of my favorite pics of a trachycarpus anywhere!what a beautiful trunk!if I was a tree hugger.....I would not want you to get in trouble with the wife but when you do build a bigger box hehehehe do it in private and I will send you a card saying that it is a gift from me- lol,think it will work?

Arctictropical, you wrote: "...I will probably try a heating cable with thermostat, and bubble wrap." Can you elaborate on that, or is that still an idea-in-progress? I'm trying to picture in my mind exactly what you would do, but I always end up with unanswered questions. Thanks in advance.

DLN949

Jim, I think I got away with still using the 8' box this year by using two levels of railroad ties to place the box on top of. This is technically not building a bigger box. My wife can't get me for this. I suppose next year I could add a couple more levels of railroad ties. DLN949, since my aquaintence in Bountiful, Utah protects 20' palms with bubble wrap and christmas lights, I thought of putting a layer of bubble wrap around the trunk and fronds (I tie them together anyway to get them under the box), then a heating cable with thermostat, and then another layer of bubble wrap. My wife won't let me use the Christmas lights. She has seen my friend's lit up palms with the Christmas lights in Bountiful, and she said in essence, "no way Jose". Do you think the heating cable may work instead?

Kevin

arctictropical, I don't know if the heating cable idea will work. I've thought about that. However, right now as I am typing this message I am looking at the safety instructions for some heating cable I have - I always keep it near my PC (doesn't everyone), one never knows when one may need to refer to it. Anyway, it has all kinds of warnings about not letting it contact stuff that easily burns or melts, don't let it be enclosed where condensation could build up, do not wrap around stuff that is not rated to handle up to 140 degrees F, etc. All those warnings make me think heating cable would be too risky.

If your wife doesn't like the light show, couldn't you use the mini lights idea, but use a final wrap of opaque burlap or something like that?

In any case, my thought was to practice on some tree or even fence post - using a thermometer inside the inner wrap - for a few cold weeks some winter so I would know the idea would be ready for prime time.

Your friend in Bountiful - He literally ties up the fronds, wraps bubble wrap around the tree, wraps the lights around the tree, then puts on a final layer of bubble wrap - and that's it? For each of the layers of bubble wrap, how many times does he go around the tree? Does he use mini lights or the C2 lights? How dense are the lights? Does he mulch at the base? I assume at the end of winter the bubble wrap is thrown away. Where does he get the bubble wrap from? I don't even know - are there varieties of bubble wrap, is there a heavy-duty type suited for outdoor use, and are there different r factor ratings?

Have you looked at what iowapalmz5 has done: http://forums.gardenweb.com/forums/load/iowa/msg0102085120357.html

DLN949, I just spoke with my friend in Bountiful who has about 10 large outdoor palms. His entire yard looks like you uprooted it from Los Angeles. He now uses C7 Christmas lights on a thermostat and one layer of bubble wrap. Regarding the fronds, he wraps the fronds together with rope and then binds the fronds with clear shrink wrap like they use on goods shipped on pallets. He also uses the shrink wrap to secure the bubble wrap to the trees. He has 30' Mexican Fan palms that he puts 4 PVC pipes up the trunks first, to give a dead air space before adding the lights and bubble wrap. I'm trying to get him to post some pictures. Hopefully he will do so this weekend. I may end up using lights and hide them to keep the wife happy, with something like burlap like you had suggested. I wish my dang Trachy would not grow so fast!

Kevin

DLN949, I forgot to mention that he buys the bubble wrap from some shipping supply companies in Salt Lake City. I think it is standard bubble wrap. He uses both 12" and 24" wrap. He does put some bubble wrap around the base of the trees and throws some sand on top to keep it down. It sounds like he re-uses the bubble wrap.

Kevin

Sounds like a winning plan all around!I am doing this with the fan palms as you know and a butia that will be planted next to the washys,I can definitely say that those c-7 lights a re cost effective way to go,a strand is only $6-$7.oo,I reduced my # of bulbs that are on from 13 to 3 and instead of 111F inside the temp was 70F,much better,what I like is that I can just screw in another light or 2 when we see 0F and less this winter I am guessing I won't need more than 4or5 to keep them warm this winter and the wrap already stays 5-10F warmer than outside temp,all this will change as these palms get bigger to more of a system like you guys are talking about.It's nice to have other people to share information with!thanks guys.

arctictropical, thanks for the replies. How does Bountiful differ from a zone 4 type winter? Also, how much dead air space does he try to create around the trunk - just a few inches away from the trunk?

jimhardy, do you have a rule of thumb on how dense the c7 bulbs need to be? (For example, how many bulbs per foot of trunk? How many bulbs for the crown area?)

Thanks.

dln949

artictropical, I forgot to ask one more question about your friend in Bountiful. What, if anything, does he do to avoid moisture buildup between the bubblewrap and the palm? Does he poke several holes in the bubblewrap to allow it to "breathe"? (How many such holes, and of what size, are required?) Or, is moisture buildup simply not an issue?

Thanks again.

dln949

Very impressive! One thing you can do is wrap up the root ball in burlap, tie up the fronds, and ship it to me in Central Florida. :) Great work, beautiful palm!

I am thinking that the compact flouescent bulbs give off more heat than one might think, through their transformers, which seem to get warm. They are at least cheap to use.

Wow! Lots of replies. My friend in Bountiful is about 80 miles south of where I live, in the Great Salt Lake Valley, which is lower in elevation than the valley I live in (Cache Valley). He also lives up on the "bench" area of Bountiful, the foot hills of the Wasatch Mountain Range. Several things contribute to his zone 6 rating, lower elevation, living up on the foothills where cold air drains away, more urbanization, and a little moderating effect from the lake. I live in the bottom of my valley, out in the open with nothing but farm land around, where all the the cold air settles to. According to most authorities, the coldest temperature in the lower United States exists up in the top of the mountains east of my home about 20 miles away, in a place called "Peter Sinks", where they have recorded -60 F. temperatures before. It freezes there every month of the year. This wonderful cold air seems to flow my way. Regarding my friend's bubble wrap, I don't think he worries about moisture behind the wrap. My boxes are certainly air tight, and I have never worried about moisture build up. Whenever I pop the boxes off in the Spring or Fall after the lights have been on, the climate is similar to a greenhouse....warm and humid. Yes, the florescent bulbs put off more heat than most people are aware of, and are a very economical way to heat my Styrofoam boxes. I don't notice a huge jump in my electrical bill during winter.

Kevin

Could a fluorescent make it too hot in there? I dont want the palm to require water. It's also pretty much impossible for me to check on the tree while the insulation is attached to the sides. Anything that could let me in could be a draft.

Could the light be a bad thing on 45 degree days?

http://www.improvementscatalog.com/product/3-outlet-outdoor-timer.do#

I thought about using this, It could be set to turn on during the night.

I would not even turn on a light or heat for a trachy unless its below 20F and I am sure you could get away with less as long as its dry,last year I would only turn my heat lamp on when it was below say,15F but I was babying mine because it was planted in Nov,the only times I turned the heat on when it was 15-20F was if it looked like we were not going above freezing for a few days but my trachys easily delt with 2-3 days near or below freezing,they are very cold hardy if they have some time to harden off and are kept dry.I used a heat lamp in mine as a trade off for more sun,one layer of clear plastic gives you a 40F bump on a sunny day and more like 80F with 2 layers,I like the idea of using a single layer of plastic,when the high is forecast to be around 30F or so I open the flaps so they won't overheat and if is below that I keep them closed all the way to near 0F because its 40F warmer on a sunny day and if its cloder than single digits I close the whole thing down,no sun and a tarp over it with heat on and keep them at an even temp.
dln949,I don't know any formula with the x-mas lights,I think it depends on your insulation,I do know that you don't really need or want bulbs over the growth bud as all the heat rises anyway but I do know you wan't a little light up there but not enough to let the leaves overheat from sun,so I think a couple layers of burlap is the best plan,I also locate my thermometer at the bud and concentrate the lights near the bottom of the trunk because as mentioned the heat rises anyway.