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Palm tree protection continued

This Washingtonia robusta was going to be difficult to protect because of its location in a raised bed. I was concerned that even if I protected the tree, the roots would freeze because the raised bed would be exposed to the elements. Another concern was that there was really nowhere in the vicinity to tie down to for support to resist wind. This called for a different, more extreme type of structure that could stand on its own.

First I cut off all the fronds that had their petioles lower than a 45 degree angle from vertical.

Next I used a piece of steel pipe (2" Sch 40) and a sledge hammer to "drill" holes in the ground. Every few inches of pounding you remove the pipe, clean out the dirt, and start pounding again until you reach the desired depth which in my case was about 2'

The PVC pipes are are the exact same diameter as the steel pipe, so they fit nice and snugly into the holes drilled. I installed these 2" Sch 40 pipes so that their tops are just below the surface of the bed. During the summer I cap off the holes and cover with mulch. They are completely invisible.

Now the main vertical structural supports get installed. They are 1.5" Sch 40 PVC pipes which happen to fit perfectly inside the 2" pipes.

Next I build a truss system out of more PVC pipes. All the intersections were marked and drilled and then fastened with carriage head bolts. The top of the vertical supports was finished with a roof type frame that's just more pipes at 45 degree angles going up to the center.

In this picture it looks like the structure is unnecessarily tall. I purposely built some extra room in it so I wouldn't have to build any more the following fall. Turns out that after 1 growing season, the palm barely fit into the same structure the following year. That's about 2' of growth.

The entire structure is wrapped with greenhouse film using a vertical overlapping seam. The seam is fastened with a really cool device called wiggle wire. There is an extruded aluminum housing for a stainless steel wire spring to be "wiggled" back and forth to secure it inside the housing. Once complete, the joint is as strong or stronger than the plastic film itself.

Here's a glimpse of the final product standing next to my more traditional wire fence structures. The PVC structure obviously cost quite a bit more than the wire fence structures, but the PVC structure is going to be modular. Each year the robusta grows, I can add more sections of vertical supports and trusses to keep expanding the hut.

The structure successfully protected the palm all winter and even with a few nasty windy winter storms, the structure held its own.

Some common concerns and myths debunked!

Clear plastic will fry the palm: I found that my enclosures would be about 40 degrees above ambient temps on a sunny winter day. Hypothetically you could have an 80 degree winter day and that would allow inside temps to reach 120 which could be harmful, but around here a 70 degree winter day is extremely rare, so I've never had any problems.

The enclosure needs to have ventilation to give the palm fresh air: I keep my enclosures as tight as possible the entire protecting season (5+ months for Washingtonias) and never had any problems.

Also related to the above concern, you need air circulation because stagnant air can cause mold, rot, etc.: Never used any type of air circulation ever.

The plastic walls create condensation which makes it like a sauna in there: This is actually wrong. Think about how your air conditioner works. You start with warm, humid air that was in your house before you turned on the AC. Then you run it across very cold coils. This not only cools the air, but causes much of the humidity to condense out of the air. Your houses air conditioned air is NOT humid. The cold walls of the enclosure do the same thing to the inside air. It not only cools it, but also dehumidifies it. The excess water drips down the side walls and into the ground. No problem! You should keep leaves from touching the walls though because the excess water could follow the leaves down into the crown and pool up there. As long as your leaves don't touch the side walls, it's fine.

The extreme temperature swings caused by these enclosures from day to night are very hard on palms. No. Mine experience 60+ degree temp swings regularly and show zero ill effect.

If the electricity goes out on a very cold night the palms will freeze: That is correct. Luckily my community has underground power lines and in the 12+ years I've lived here we've never lost power for more than a couple of minutes at a time. Buy a generator if you're worried.

The roots will freeze as the ground freezes, and even more so in the raised bed, which will kill the tree: No Problems! Roots look fine in spring.

As the palm tree grows, protection will be increasingly difficult. What are you going to do when it's xx feet tall?: Quit your whining and plant some palm trees!

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