Two weeks back I cut down 10 dead trees at 10’ lengths. I’m pretty certain 7 of them are elm, the remainder could be maple I’m not sure. They vary in thickness near the base, probably 6-11". As can be seen from the picture, I have debarked, burned and applied Lifetime Wood Treatment to each post. Some logs have cracked a bit on me also, and I do still see some bugs habitating inside despite all that has been done (perhaps not issue).
These are supposed to be the verticals for a kiwi trellis build, which I’m hoping to get a long life out of. I have the holes dug already and my plan was just to put the posts in the holes and fill back in with dirt. I am second guessing if I should instead save these for a different project and instead go out and buy 10’ cedar posts at either 5-6" or 7-9" thick. I could too treat with the same wood treatment and burn as well. What are some of your thoughts on longevity going either route?
I used steel for my fences because i know they will still be in the ground in 50-200 years unless steel becomes very valuable in the future.
It is not cheap now which is why i make that comment. The next big project - #154 by clarkinks
Probably for a trellis the least cost permanent method is to use sackcrete to anchor 4” black poly sewer pipe in the ground- solves the rot issue for a lifetime. Then on top of the black poly simply build your trellis on whatever long lasting wood, preferably cedar to suspend your trellis wires. Works well for any type of vines. Pm me if you want to see mine for a concept
Dennis
Kent, Wa
Our untreated eastern cedar posts lasted less then 10 years in the ground. We cut the posts for free which was great. Not sure how much longer they would have lasted if they were treated or burned. I’m also not sure how Elm or Maple would compare to the Cedar posts we used.
I see the vinyard next door is replacing their cedar end posts after about 10 years. They are about 8 inches in diameter and untreated.
We use CCA PT fence post now. They last longer than the plants they support
Where you live, you should have access to Osage Orange posts. They aren’t expensive and should last 100 years. Elm and maple won’t hold up. No need to do it all over again later.
When we do four by fours treated for posts. We go four feet down. Concrete is poured in first, then we use pea gravel to fill holes up. Keep the water away from the posts. They last 30 to 40 years. Even longer in dry areas.
Remember they used to put gravel in the bottom of pots but learned it actually stops drainage. When soil textures change the water stops. Same thing here, the water in the soil stops at the gravel. Sand can be used too. It works the posts stay dry.
i used pressure treated 4’’ x 4’'s leveled on concrete pads then treated them 2 yrs later with eco wood treatment made in B.C. it’s a mineral treatment i used on my fir raised bed and it lasted 8 yrs. amazon sells it. silver box.
The Maple or Elm post have very little rot resistance on their own. The chemical treatment will help some, but that will vary depending on how much of the chemicals were absorbed. If the post are green (freshly cut down from live trees) it’s likely that the chemical treatment will not accomplish much.
I myself would not use post made out of Maple or Elm for anything that I want to last longer than 3-5 years.
Cedar has pretty good rot resistance, but even better and way stronger would be: Black Locust, Osage Orange, or Red Mulberry .
Is the charring for aesthetics or rot prevention? A couple University studies have shown charring does nothing to prevent rot and may actually promote it. I believe there’s a USDA Forestry Service study drawing the same conclusion. Unfortunately, you may be better off with a different material.
Can’t drive nails or staples into aged Osage. Result in bent nails or staples. Have to drill small holes into Osage for the metal. Other than that, makes excellent post for dog pen though.
I’ve heard of folks using Osage for false teeth. I bet they didn’t rot.
Osage will also tear a bandsaw up. Ask me how I know.
ive got a few black locust growing up in the orchard that i plan to coppice for fence posts, tool handles, fire wood etc. it also grows very fast. it was commonly done on farms in Europe centuries ago.
Yah, Black Locust is one of the most “under rated” trees in Eastern US. Very beautiful lumber, good tool working ability, high rot resistance, very high BTU firewood and like you mentioned fast growing. Thats a combination not usually found in wood, most fast growing trees make poor firewood.
Speaking of firewood I had a 35 year old Honey Locast cut down. I hand split wood. The big pieces at the base were so hard I had to wait two years for it to be dry enough to split. Wedges slammed with a heavy sledge into wood popped out like champagne corks.The wood was the best firewood ever. Way better than red oak.
I use pressure treated wood for posts. They are fine for five years, and after that for any post that weakens I just pound a metal stake next to it and secure the post to the metal. The wood above the ground lasts forever more or less, 20 years so far for mine and still going strong.
Since you have those posts already I would just use them, and plan on reinforcing in a few years.
In 2001… I used 4x6 treated pine posts 8 ft … for my illini blackberry and grapevine posts. They are still holding strong. Solid… looks like they could go another 20 easily.
I recently got the same for my new muscadine trellis posts.
5 years ago I built a kiwi trellis using pressure treated 10ft 2/4’s for posts. It was just a trial for kiwi growing and I wasn’t sure it was a good location so I was wasn’t concerned about longevity. Only took a few hrs to build. Just checked them. They look like new except a little warped. No problem supporting the weight so far.
I like the kiwis and plan to build a new trellis in a better location and I’ll use some 4x4 posts that were given to me.
