Durability of Eastern Red Cedar

Short answer: it's the heartwood that is rot-resistant. But you'll learn more than that from this discussion. April 11, 2008

An older farmer had me cut the heartwood of eastern red cedar into fence posts. He said he did not want any "white" on the post, as it will not last as long. Growing up on the farm, we just dug a hole and stuck the post, bark and all, in the ground. Anyone else heard of this?

Forum Responses
(Sawing and Drying Forum)
From contributor K:
Good choice for the farmer. The red heartwood is decay resistant and the white wood is not. I have a similar species, western juniper. I roll my eyes when people stick six inch diameter posts in the ground and proclaim them rot resistant. Within five years the only thing holding that fence up is the one inch of heartwood in those small diameter trees.

Sticking a post in the ground is cheaper, simple and effective if that heartwood volume is adequate. I don't think the bark matters.

I sell 6x6 landscape timbers. I square off a 10 inch top diameter log to get them. I throw the slabs into the firewood pile. I expect a minimum of four inches in diameter red heart wood at the top of those timbers.

For most species the best wood is the outside of the tree. Interesting that for western juniper and eastern red cedar, the "jacket" wood is the least valuable. That aromatic red heartwood is where the market lies.

From Professor Gene Wengert, forum technical advisor:
Contributor K is indeed correct. Several other species have decay resistance naturally in the heartwood... white oak, black locust, other cedars are a few. Although decay on the sapwood might not be too bad, that is also where the fence staples or nails are, so they will not hold well after a year or two.

From contributor T:
Putting them directly into the ground was common around here. Nowadays most are going to tractor supply and buying treated.

What contributor K says is correct, but you also have to consider that the percentage of sapwood in ERC varies from tree to tree. I hoard red-to-the-edge ERC. It's rare around here but on some trees sapwood is virtually nonexistent. Some will have less than 1", most will have 1-1.5", while some will have 2"+. The wise old farmers here are picky about the sapwood and will rake you over the coals if they see too much. On the other hand when they spot my personal stash they want to buy them at the regular price and wonder why they're not for sale.

Contributor K, I understand there's a demand for sapwood cedar boards that show some heartwood contrast. Are your slabs too small to be processed or is the demand nonexistent in your area?

From contributor K:
Most of my slabs have profound taper (four inches wide and an inch thick on top, with ten inches wide and three inches thick on the bottom). Even then there is little heartwood visible. My logs are 8 1/2 feet long.

I do not have a profound color contrast like Eastern red cedar. I do have the same customers, looking to get the all best posts for a worn out dime and a handshake. God Bless them. I do not have any market value in my slabs at all.

From contributor W:
I see where they are selling juniper posts as organically safe for gardens and vineyards, something to think about. No treatment needed.

From Professor Gene Wengert, forum technical advisor:
Eastern red cedar is actually a juniper... It's Latin name is Juniperus viginiana.

From contributor J:
I grew up on a farm and we never used pressure treated posts. A 6" (small end) cedar post will last 20-30 years.

From the original questioner:
Thanks for the responses. Logs were 7"-9" in diameter, cut down to roughly 5" square posts. How much strength is lost from removing the extra wood? Also, would it be worth the time to run them trough the planer to smooth the sides (less water penetration)?

From contributor W:
Juniper fence posts sell quite well. They are selling for more than RR ties. And the story is that RR ties are being banned due to the creosote. So I look for the market for juniper to expand. I have had several outfits wanting semi-loads, but I'm not that big an operation. So there is an outlet for the small logs.

From Professor Gene Wengert, forum technical advisor:
I have never heard that smoothing with a planer will reduce water absorption, so I would not suggest it. An 8" diameter log has a cross section area of about 50 sq inches. A 5" rectangular post has 25 square inches. So, the strength is reduced substantially... 50% or more depending on the specific strength factor.

From contributor C:
For the Springfield, Mo ERC conference where I spoke on properties of ERC, I took a 4" at top round fence post that I had put in the ground in 1980 which I pulled up and cut cross sections. The post was put in the ground about 2 feet. I took cross sections at 3" from the bottom. Sapwood present, but discolored and some deterioration. Cross section at ground level, heartwood no deterioration, sapwood completely gone about 3 1/2" diameter of heartwood at this point. Sapwood on this post was about 3/4" thick. At about 8" above ground level the sapwood was all present and sound holding staples well. There was no bark on this post, as it fell off the first few years. In checking some of the other posts in this line fence, all cedar posts were still functional. None broke off. Our policy when selling ERC round logs for fence posts is to keep sapwood to a minimum. 3/4" or less of sapwood and 3" of red at the small end. For ERC, the important thing is how much heartwood is present at ground level.

From contributor T:
The reason you get differing opinions about the longevity of ERC posts in the ground is because people have different experiences with them. A rancher/farmer owns several hundred acres next to my land. He started using the ERC off his land 20 years ago for fencing. He said many of the posts are still sound (and I know they are because I have logged the property), but some of them start needing replacing after only a few years. Same trees, same soil, same everything. A post would "go bad" right between two good ones.

I have heard disparate views of using the logs in the ground from many people in this area. The only thing I know that is in common is that they are all telling the truth, so there seems to be some elusive factors that determine the longevity of this species. I have heard a few theories about why this is, but I have not heard any I know to be founded on scientific study, and I don't know what they are myself.

From contributor Y:
The slower an eastern red cedar grows, the more red wood it has. A red cedar growing on a rock is nearly all red wood.

The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).

Comment from contributor A:
I think this is a much undervalued and beautiful wood that should be included in more of our wood projects, not just used for fence post. Here in eastern Texas the trees can and do get rather large 36" DBH. I've collected several this size and had them milled. Itís really nice wood.