If I made a sqft garden over sod, how deep would the dirt on top of the landscape cloth need to be?

A minimum of 6", but deeper is better. Mine is 8", and does very well.

Also, how are these type of gardens for water? I would think they would dry out quicker?

They definitely dry out quicker, and you'll have to water more often - depending on your climate. I live in NW Alabama, and water mine every 2 days, with excellent results. I hope this helps...

EG

Mine are all 12" tall but not fully filled. You should expect some settling and it will definitely level out a bit. This was my first year, so that's all the info I have.

Thanks. I think I will start out with only a couple this year, and if I like them, eventually make more. I have a fairly large vegetable garden area. I'm not good at distances but I would say at least 100'x20'. Maybe I'll start on one side and do two 4x8' boxes and plant the rest this year rows like normal...if I like the sq ft approach, I'll add 4 more boxes a year.

Yet one more question. What do you all use to construct your boxes out of?

I think that starting with only 2 next year is a good decision.

Boxes can be constructed with concrete blocks, bricks, and all kinds of lumber. Probably 80% build theirs with treated lumber. I would suggest not going with 2x6's, because your box won't be deep enough - once the soil has settled. Instead, go with 2x8, 2x10, or 2x12's.

EG

Interesting comments on watering. Although the raised boxes dry out faster than the ground, when you use vermiculite and peat moss, both hold water far, far, far longer than soil does. So what I've found is that while the top half inch and inch around the sides dry out quick, if I dig down an inch it's moist. In the heat of the summer I water every other day, but right now I go several days without water even though the beds are under hoop covers.

And I used pressure treated 2x6s (three high) because in our PNW climate any other wood would rot too fast. I don't think I'd do 18 inches again, 10-12 would be just fine. Besides, the higher you go the more Mel's mix it takes to fill it, hehe.

Good luck, there are pros and cons for both but it's great that you're trying it out. You may find it best to use them for fall/winter gardening because of the ease of building and utilizing cold frames and hoop covers on raised (wooden) beds.

Good luck!

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

I have 2X6 beds now. My new ones are going to be 2x12. I was shocked at the amount the soil settled.

Really Ribbit? I hear that from a lot of people. Mine didn't settle at all. I kind of wish it would so I could add more compost easier without going taller than the wall of the bed. Odd is all.

Let me qualify that, Sinfonian....I used potting soil and not Mel's mix. Don't know if that made a difference, but judging by everyone else, I'll say it does. The soil level now is miniscule to what it was (almost overflowing). I attribute that to most of my problems this fall. I'm expanding this spring and I'm going to fill them a month or so before I start planting in anticipation of the settling that will occur. I'd say that right now there's less than 3.5 inches in there.

Three and a half inches...ouch! Yeah, that'll cause a few problems with some veggies.

EG