How long do wood SFG boxes last?

I've used other materials, but now I have some wood boxes build to the official plans. How long can I expect them to last?

Hi, DK. What type of wood is it, and how thick? Will they be resting directly on the ground?

Are they made from 2" x 4"s or thinner wood? Are they on weed fabric or directly on the dirt or on legs (table top)? They should last a handful of years. Hopefully, others with old beds will chime in.

One piece - 2" x8" on the ground and beginning to rot, after the fourth year. The rest I reckon will last another year or two, three if I am careful.  Non-painted, non-sealed, non-stained. Not sure what the wood is  but not cedar for sure. Cheap white wood with knots in. A job lot I bought and had to cut the bad bits out.
Is that enough info?

That sounds about right, 4 years plus. The wood you bought was probably pine or fir. Mine were on the ground for 18 months but the termites did a number on some of the 2 x 4s touching the dirt. When DH raised them or converted to table tops, some of the bottom boards had to be replaced due to the lack of intact bottom to screw the plywood bottoms to. Does that make sense?

Mine have been on the ground for about 8 years and are rapidly rotting out at the ends.

Boards were pine, 2" x 8" - untreated and screwed together with plates.  One bed has had stakes added on the outside to hold the boards together and should/may last another year or two.  The stakes are just contractor-type short stakes and I need to make more for the other 5 boxes.

Maybe if I had painted the ends of the original boards, they would have stayed together longer - who knows?

I don't remember if my very first ones were 1X's or 2X's. I'm pretty sure I did some 1X's, but also used cheap, untreated wood, and they were functional the 5th year, but 4 years without reinforcing, or needing to hold my breath and hope real hard, seems about right!

My original SFG was built as a sandbox for my kids about 17 years ago using pressure treated wood, and I converted it to a SFG about 7 years ago......I wouldn't use that as an example, and I don't recommend pressure treated wood for gardens to be on the safe side. 
Untreated lumber is lighter and easier to work with anyway.
 I built my current SFG using 2" thick lumber from Lowes (spruce pine fir, I believe).  I've gotten 3 years out of it so far, and it looks like I will get a couple more. It sits on top of weed cloth on the ground, and we get a good amount of rain and snow.

My beds are pine wood 2 x 10's or 2 x 12's.  You can do some easy things to try to extend the life of the beds.  I used raw linseed oil on the wood to try and make mine last longer.  After a year they look just as weathered as the bed I did not treat and I have no idea if this will preserve the wood for a longer life.  I hope so because it was time consuming putting on three coats.  Also, the weakest place on the beds is where the end piece of one side is screwed into the other side.  I used L brackets to try to keep them together longer.

So far my beds are only 3 years old so I do not really know how long they will last.  I am expecting at least a total of 6 years or more.

The cheapest part of SFG is the building of the bed (a whole lot cheaper than the Mel's Mix) so it won't cost much to make new boxes when these are no longer functional.  And as Cajun Cappy says, it looks easy to replace them when they do start to fall apart.

These set on the ground for 18 months before we converted them to table tops/raised beds:
This one is upside down showing the termite damage to the lowest 2 x 4".

There is a guy down the street from my grandparent's house who appears to be doing SFG without boxes -- just well manicured, rectangular mounds of dirt.  I'm not sure if it's "Mel's Mix", but he has consistently got the best garden I have seen.  This spring, I'm going to go talk to him and see / hear all his secrets.  When my wood frames rot away, I'll hopefully have enough information to go about his route.  Something to consider.

My first raised bed went 10 years before I had to replace 1 plank ( 2 X 8 X 10 )  untreated, unpainted, unsealed pine.
It started leaking soil so I had to do it.
All the rest are treated, painted and/or sealed.

My nine 4 x 4's have been in the ground going on 6 years, untreated spruce.  Two of them are rotting along the bottoms.  Some of the others are just separating from their metal braces.  All in all, they served their purpose.
I also have 3 berms which are raised hills of soil without any support on any sides.  They work just fine and particularly for a long bed.  Mine are 12' and two are 16' long and 4' wide.  They have lasted as long as the wooden ones with just a little rake-up of soil over the tops in the spring and adding compost.
A great alternative.

Thanks for all the data points. I've used everything from 1 x 6 pine (needed stakes to hold it in place) to concrete blocks. (I still haven't  found a satisfactory way to either plant in the holes or keep weeds from growing through them.) 

I got some ready-made SFG boxes from my brother when he moved. They appear to be made from 2 x 10 pine. I'm not sure how many years he used them.

I have had mine 5 years and they are doing fine BUT I used treated lumber.  I know that is a no no with most here but first I would like to mention that the treated lumber today is nothing like the treated lumber 40 years ago.  It is lightly treated compared to the good old stuff.

Next time though I will go with the untreated stuff.

I used untreated pine 1x8 boards. After 5 years I have replaced &  moved the 4x6 boxes I built 5 years ago. The wood is getting a bit punky and I moved the boxes to my flower beds where they will be useful for a few more years but will eventually root in place.

I'm about to start a first-time SFG garden and I will be heading to Home Depot in a week or so to get some lumber. I know the book encourages reuse /recycling, but so far I can't find anything useable. (Lots of spruce/pine/fir, but nothing durable).

I was thinking cedar (red or white), but I have also been looking at the thermal-treated outdoor wood. The manufacturer's information says it is non-toxic (no chemicals are used in its treatment). It's half the price of red cedar and about 2/3 of the price of white cedar. Does anyone have any experience with this material?

I'm less than a year into this type of gardening, myself, so my opinion is based more on hearsay than personal experience.  That being said, I asked the guys at the lumber store how much better the cedar would hold up compared to untreated lumber.  They said the cedar would probably hold up about 50% longer.  Yet the cedar - in this market, anyway - is more than double the price.  Considering how easy it is to build new ones every 3-4 years, I decided the benefits of cedar were not worth the additional cost.

As for the treated lumber, I learned from our local university research extension that the newer treated lumbers are non-toxic (they're treated with copper, which is advertised as an "organic" non-toxic anti-fungal).  So I no longer have quite the trepidation to use it as I had before, but I'm testing with only one of my boxes to see whether I think there are any problems with it, or I think it will hold up better than the untreated.

Look forward to seeing what the others share about this...

We went with non-treated 2x8's. 

I wouldn't trust the copper-treated either.  Copper is still toxic in large amounts.  

I don't feel comfortable with exposing plants I want to save seeds from to that. 

Nor do I want to expose myself & DH to more copper than we need physically (if you know what I mean).


One other thing, Fred - if you have a fence-line, you'll want to make sure you block grass, etc. from growing under the fence/between the fence & bed.  Ask me how I know...    Boy, is it a PAIN to get rid of once it gets established...!

I use 6' rough cedar fence pickets with a nailer in each corner...double heights makes great beds for carrots, sweet potatoes, etc.  I stock up when I find them on sale.  I have them cut 2' off each board so I can make one 4x4 and one 2x2 bed.  I'm on year two and they are holding up well.

I recently saw a youtube video of someone using Hardy plank siding (concrete board) as it will not rot, but it is thin and can be brittle...it may be a cheaper alternative to synthetic lumber like Trex, Geolam, etc.

I just noticed this week that one of my original (pine I believe) boxes is starting to 'fray' at the corners.  Probably 2 good years left in it which would then make it 5 yrs old.

CC

5 - 6 years looks like the maximum I will get out of my 2" thick pine boxes also.  I did treat them with raw linseed oil.  Don't really know if that was any help or not.  They look fairly good up top but down near the original ground level, they are beginning to decay.

Simple solution to using treated wood is line the inside of the box with plastic.  Also they can be placed on a row of patio blocks (or bricks) as in the foundation of a house.
This is what I,m going to do when I need to replace any of my original boxes.  I have (2) 4x4 2x8 pine that I wrapped in plastic, "don't do that again" that are 4 yrs old and (2) 3x6 2x8 pine not wrapped that are 3 yrs old.  They are all still solid and placed directly on the ground with weed block or cardboard underneath.  I also have (2) 3x6 freestacked brick, 3 brick high x 2 brick wide, on weed block.  

CWJ

The longevity of your boards depends a lot on where you live.  In the hot, humid climate of south Louisiana 5 years is a good estimate.  It is so hot and wet that I don't see the point of spending the extra $$ on treated lumber.  DH is building new boxes for me and he purchased treated.  His $$.  I am just very happy to have new boxes.  I will line the sides of the boxes as well as the bottom with commercial grade landscape cloth.  It is MUCH to wet to even consider using plastic. 

Best to you all.