If you are looking for something cheap you can use untreated pine or spruce 2x6 this is this stuff they use for wall framing in your home. The problem with this is it will rot over time but should last at least 6 years, by then your Mel's mix would probably need nutrients added to it anyway so you can just start over.

If you want to invest more $$$ for a frame that will not rot you can use cedar, red wood or even the new plastic composite lumber. This will double the cost of material but you will never have to change it.

The people in the lumber department of your local home center can offer a lot help with selecting material that will work best in your area and can even cut everything for you if you go in with your measurements.

I would not use treated lumber for this purpose, it has some really nasty chemicals in it. Does it actually go into the veggies, who really know?
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Check out my veggie garden blog:
http://veggiegardenblog.blogspot.com/

I wanted it to last more than a decade, but wanted relatively inexpensive, so I went pressure treated. They report that the new chemicals are safe, but most of my evidence came from my brother's decade with the same wood with no problems. If you're worried, then you're going to have to replace it sooner.

I don't believe Trex or the like is firm enough to hold together in the longer boxes, though you could stake it maybe. It's also major expensive.

It's all up to you, your budget and your comfort with the material.

Whatever you choose you won't go wrong.

Here is a link that might be useful: Sinfonian's garden adventure!

I used bared untreated wood and coated it with Australian timber oil. It is basically linseed oil with resins. After 1 year no signs of decay. It will probably put it up there with cedar.

I used red cedar, because I didn't want to build another one any time soon.I look at it as an investment.It should last a good 20 - 25 years.Who wants to build a new one every 5-10 years? Besides, ten years from now, I would probably have to hire someone to build it for me, because of physical reasons.

redwood or cedar..... invest now for long term beauty and resistance to rotting

you are filling it with wet dirt remember!!

I made mine from 2x8 spruce and painted inside and out with boiled linseed oil. Two coats on the outside. I am going to apply some exterior-grade oil-based urethane to the outsides to see if I can keep it looking fresh.

I don't mind if my SFG's only last a few years. This is my first attempt at any kind of gardening, and I didn't want to spend too much on longer-lasting material. Redwood or cedar would have been several times the cost.

I figure if I live in this house long enough for my current boxes to rot, I could just add corner posts and face the outsides with 2x8 pressure treated lumber.

Pics of my SFG at the link below.

Here is a link that might be useful: yrdling sfg 2008

yrdling......if that suits you, then I think it's a good decision. By the way, very nice job on the boxes - they look spectacular. I think when building a box, beauty should be one of it's greatest attributes to consider. Good job!

I use whatever I have on hand that fits the dimensions I need. I know, I know. So pray for me.

My oldest untreated bed was made in 2002 & still going strong. Forever is a long, long time. When these need to be replaced, I will likely have better ideas anyway, ha.

Gumby_CT

I used untreated pine. I know it will rot in a few short years, but I don't even know if I'm going to like gardening. I wasn't comfortable with the treated lumber and I couldn't spend hundreds on cedar if gardening turned out to be something I despised LOL. When they rot, I will replace them with cedar or something more permanent if I find I love gardening :) .

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

Hi all. I just found SFG, usually spend my time in the Tennessee Gardening forum. I've been SFG-ing for about 4 years. When we built our house I saved the extra bricks and have used most of them to build up my beds. Weeds grow up through them (not too bad) and they occasionally tip over but all in all, I like this arrangement. I have, on occasion, changed the size and shape of the beds with very little effort. Linda

I use treated 2x8 boards without any worries. They stopped using nasties like arsenic a long time ago.

Hi all- I just purchased materials from Menards to build a raised bed. The anchores / posts are called Frame-it- All and the sides are composite (ultra deck). I saw this product on-line and was happy to find it locally. The sections are 4 ft long and you can build numerous configurations and heights. I'm going to start out with 4 X 8 X 12. I don't plan on double digging - etc. Just putting wet newspaper down and following a layered type compost filling that I read about in a book called Lasagna Gardening. This was a small investment, the 2 pack anchors were about 11.00 each and you need three, plus the same amount for the stacking hardware. The decking was on sale and the guy cut it for me : ) This is definately an easy project for a weekend warrior! An added bonus, you can move it around and change it if you want something different next year. Wish me luck!

When my boards rot out, I'm going to replace with corrugated tin. Someone else had posted this link, and I thought it was pretty cool ;)

Kristine in Ontario

Here is a link that might be useful: Southern Living Tin Bed

I used pine treated with linseed oil. the outside of the beds are waterbase stained to match the house

I used linseed oil on pine boards as well. Seemed like the best option at the time.
I did see in the Home Depot advertisement today, they were talking about the improved environmental safety of treated wood. If money were no object I'd use some kind of plastic decking.