Hi flhomeowner,

I used pressure treated wood to make my raised beds as well. If you want to, you can add a liner - but I do not believe that the treated wood will cause a problem.

Pressure treated wood has changed over the years and from what I've read, it doesn't have the chemicals in the treated wood like there used to be. The wood I used was "AC2 treated".

Here is a link that might be useful: BsnTech Gardening Blog

It's advised to not use PT wood because there are safer alternatives. That said, the stuff isn't a deal breaker for your garden.

Once built the biggest real danger is putting your hands all over the stuff while harvesting...contact stuff.

There isn't much to leach into the fruits even in the most toxic of PT lumbers. Plants generally don't pass on much soil toxins because they have no use for their uptake and very little makes it to the actual fruits.

Like the above poster said...if you bought your PT lumber recently there's an even larger chance that it's the safer stuff.

A lot of the issues with old PT lumber involved people putting their hands all over the stuff or laying produce on it to rest. Even then, a good washing takes care of most all of that. It's the arsenic in the wood that was a huge issue with the last generation PT wood and how you could accumulate arsenic levels on skins just by rubbing your hands across it. A lot of the "panic" came from how much PT lumber is used in kid's playground equipment.

Since your container is safe, you can move on to selecting crops. May I suggest radishes (almost instant gratification for children) and lettuces? Both are easily grown and require little space. You could put in some bush beans later (easy for little fingers to pick) and some parsley (I suggest buying a plant and transplanting it to the garden) and basil. A bush cucumber might be fun, and you could always put in a cherry tomato plant, one of the patio variety that doesn't get too big (I think Sweet Million is a smaller plant).
Since you are in Florida you can probably garden all year around. Just keep adding amendments to the soil so you don't wear out the nutrients!

The square foot gardening forum here has lots of people gardening in 4x4 areas. Lots of great info over there. You should have lots of fun growing veggies with a preschooler.

Here is a link that might be useful: Square foot gardening

Hi,

Awhile ago, I was watching a gardening program on TV, I can't remember which one, but they said if you use some paint/stain on the PT wood, that will seal the wood.

Last fall, I got a bunch of free PT wood that was a swimming pool deck. I am making raised beds out of the PT wood and also making a compost ben. Just to be on the safe side, I am planning on staining anything I make. I think staining/painting will make everything look nicer too.

Thanks guys for the info. I just bought the wood this weekend from Home Depot so am I correct in assuming it is fine? Would lining it help it last longer?

Also, the bottom consists of four 12" planks butted as close as possible. Will this be sufficient for drainage or should I still drill holes? If so, how large and how far apart?

"butted as close as possible" won't allow for any drainage so I'd sure drill some holes. Random pattern 1/2" scattered all over the floor about 6" apart should do it. That way the wood will last longer too as water won't be trapped in the bed to rot it. Or you could space the bottom boards further apart and then cover with fiberglass screening to hold in the soil but some additional holes will likely still be needed.

Dave

Thanks guys for the info. I just bought the wood this weekend from Home Depot so am I correct in assuming it is fine? Would lining it help it last longer?

Lining it may help it last longer, but it may not. If you line with plastic there may actually be more concerns with toxic chemicals from the plastic (it's almost certainly not a plastic that is considered food safe) than the wood and plastic can trap moisture between itself and the wood hastening rot.

I understand using PT wood due to it's lower cost, but for a 4x4x12" box, why not just get cedar or some naturally rot resistant wood? I would think that for a project of that size the cost difference would be minimal and you would have complete peace of mind.

Ultimately the current generation of PT wood may be entirely safe, but there are some valid reasons for concern. Having a bunch of forum folks say 'I use it and it's fine, not dead yet' offers very little true peace of mind.

Why not just use the new concrete stone wall building blocks? It will last forever.

There's many things better than PT wood, but it's built already in this case.

That said, PT wood...especially the new stuff...isn't thought to be a huge issue to plant or plant health. It's definitely not bad enough stuff to rip it up and start all over. The biggest knock on the new style (and the old style) PT wood is how intensive and polluting it is to produce the stuff.