My wife wants me to build an "elevated garden", and I have an idea in my head, but I'm looking for more.

The reason she wants is because (a) bad knees, and (b) underground critters that may attack roots.

What she has in mind is something about three feet tall total. Basically, a two-foot tall table, with a foot-deep "sandbox" on top.

Question 1) Being that this would be used primarily (if not exclusively) for peppers, tomatoes, and other veggies, pressure-treated wood is out. Is the only other option cedar?

Question 2) Do I need to put a plastic liner inside with holes for drainage, or would this idea work fine without a liner?

Question 3) Would it be helpful to have a greenhouse-type dome lid on hinges that my wife could lift, similar to the lid on a BBQ grill (handles on the side) or would this be overkill and not necessary?

Question 4) Would a foot deep be enough for roots of most common homegrown veggies like tomatoes, etc?

Any other tips I didn't think to ask about would also be appreciated.

Thanks in advance!

 

Going that high I'd consider some sort of masonry walls instead of wood.
I live on a slate rock mountain and even though I've been plowing the same spot for decades, I'm not sure I have any soil past a foot deep.

 

May not work, depending on how many plants you want, but we've been growing our tomatoes in clay pots for quite a few years now, and, since we've decided to stop growing potatoes, we'll probably return our garden to lawn and try peppers and other things in pots.

 

1. Pressure treated wood no longer contains arsenic so you can research it and see if you want to put it on your list of possible woods. You could also build the raised be from pressure treated and then line the box with galvanized steel or plastic so the soil does not touch the wood. Or, you can use a rot resistant wood like redwood or cedar knowing that the cost will be higher.

2. I would only consider a liner if you don't want the soil to touch the wood. Water between the liner and outer wood shell might pose a rot problem.

3. I would only do a greenhouse lid if you include and automatic opener. Even in winter it can get too hot inside a greenhouse/hot box and all it takes is forgetting to open or close the lid once and the plants are toast so, I would use a greenhouse automatic vent. An actuator is about $30 and lasts at least several seasons.

4. A foot is good minimum depth for most garden veggies. My shallow beds are 18" and the deeper ones 24". Most people tend to go to shallow with their soil depth when doing raised beds. Try to avoid the tendency to buy 12" lumber that may only be 11 1/2" then put a bottom inside that consumes 1 1/2" then have the soil an inch or two below the top which ends up giving you something less than a foot of soil depth.

 

Take a look at these examples:

VegTrugâ„¢ Planters - Lee Valley Tools

They are expensive to buy, but I think they are very well thought out and could give you some ideas about how to do yours.