If you can avoid it I would stay away from PT. I use it, but anything less would rot insanely fast.

Careful to check the ingredients on any stain you buy. Cedar is more expensive but lasts well in some climates.

Since you aren't planting an edible crop, the pressure treated lumber would be just fine, and probably the cheapest in the long run.

Granny

Here is a link that might be useful: Annie's Kitchen Garden

If looks aren't terribly important you could always get a couple pallets of cinder blocks. They'll last forever and if you want to make them look descent you could put some sort of cap stone on top.

Since 2004, pressure treated lumber has been not been made with arsenic. It is much less toxic. The new chemicals for treating lumber are alkaline copper quat (ACQ types B and D) and copper azole (CBA-A, CA-B). I don't know that they are completely safe - but they are much safer.

I removed a deck last year which was over 15 years in age. Any opinions on if I could use this wood to build boxes for edible vegetables? I have plenty of it and if the arsenic has been removed with time, would be a great way to use the old lumber. Your opinions are appreciated.

I am in Ontario too. National Building Supply near Sutton has great deals on all sorts of new and reclaimed materials. I got untreated 2"x10"x8's for a fantastic price. They have all sorts of other materials too. Definitely worth a trip!

Thanks everyone, for the input

I would use it. Just my 2 cents. I used all used wood on my boxes and I was glad for it when I saw the cost of vermiculite, lol.

I made my frames from Home Depot cull lumber. They are untreated and going on 8 yrs. old. For $2.16 and 8 sheet rock screws, I would do it all over again.

I do believe in using what I have on hand to reduce the Cost Of Gardening COG. Unless, of course, you don't mind paying $10 for a tomato.

gumby,
What do you mean "cull lumber"? Stuff that's unsellable because of defects? Did they give it away or just mark it down? I just want to not sound stupid when I go to my own H.D. to ask!
Thanks!

Yes, the cull is scrap or otherwise imperfect wood such as cracks, chips, bent, or warped and is discounted. I usu. look for the green stuff @$.51

Check all the HD's in your area, the stuff goes fast. I do daily walk-thru cuz I am near one daily.

menards has a cull bin also treated,untreated,minimum four foot sections like gumby says around 50cents a board what a deal. lowes had a rack outside but it was really cull boards all lumberyards get inferior lumber just ask bet they would love to deal on it.

@dkolter We also ripped down a 15 year old deck made of pressure-treated lumber. We are using the 2x8 boards for our raised bed frames.

I've attached a link to an article I've found helpful.

Here is a link that might be useful: Does Pressure-Treated Wood Belong in Your Garden?