Will Cypress Withstand Ground Contact?

[DieselDennis]

Wanting to do some borders in the garden.  

Currently have the landscape timbers that sell for $3 ea at the BORG.  Not impressed with the longevity.  Knew that at the beginning, but they were cheap.  

Considered cross ties.  I think this would win long term, but the cost does add up.  And then there's the potential creseote leaching issue.  

Now I'm considering cypress.  There's a mill local to me that does a lot of it.  Thought I might get some of the off slabs.  Will they stand up to ground contact for 3-4 years?  

I'm only looking at going about 8" tall.

[Willyou]

I don't know about the cypress. However, my deck supports are PT 4x4s that are treated for ground contact. They have been in the ground for 20-30 years without issue. Even my fence posts that are not labeled for ground contact last a long time before finally rotting.
If you are making raised beds, have you thought of using PT 2x8s set on edge? Again, for ground contact, of course. I don't think leaching is an issue, but what little there might be will not go horizontally very far.

[joe1086]

However, my deck supports are PT 4x4s that are treated for ground contact. They have been in the ground for 20-30 years without issue

True, but the PT you buy today is not what we all bought 20-30 years ago.

[jteneyck]

Black locust will last 50 years in the ground.  Nature's PT.  

John

[cams2705]

Black locust will last 50 years in the ground.  Nature's PT.  

John

THIS!

I just put in some post and rail fence with locust posts and hemlock rails last year.  The posts are heavy and dense as all get out.  They recommended not cementing them in or even using stone in the post holes and just backfilling with dirt.  They are supposed to last ~25+ years untreated.  I'm going to spray a coat of Thompsons on it this year after letting them dry out for a year and before it starts to gray.

[FS7]

Black locust will last 50 years in the ground.  Nature's PT.  

John

More than that. A friend of mine has a house in Pittsburgh built about 120 years ago. It has black locust columns in the basement, and they hold up the entire house. Still going strong.

[Willyou]

True, but the PT you buy today is not what we all bought 20-30 years ago.

I wondered how long it would take for someone to make that point. Is there any evidence to prove there is a difference? Just a question. Not meant as an argument. In any case, the OP is only asking for 3-4 years.

[FS7]

Landscape timbers are basically designed to be replaced every so often. That's why they're so cheap.

PT dimensional lumber rated for ground contact will be far more durable, 30-40 years or more. Spend the money up front.

[fredhargis]

If you're only looking to get 3-4 years out of it, the Cypress should be good....and it just might last a little longer that that.

[AHill]

Cypress had very good rot resistance. Consider it grows a lot in swamps. There are better woods for long term rot resistance (e.g. black locust mentioned above), but cypress isn't such a bad choice.