Soil depth question.

[Dixana]

The hubby can't get the cement out of the garden. It is about 3'x3' and at least 8" deep (we never found the bottom).
Therefor, we're srrounding the whole thing with railroad ties and filling it in with dirt.
Is 8 inches of soil enough for plants to grow over that cement? There is about a 3x4 inch hole in the center that's all dirt.
I'm thinking I'll be ok as long as I plant peas and beans and more shallow rooted things there.

Thoughts?

[Kisal]

You might want to use something else for the walls, other than railroad ties. I'm not sure that the treatment used to preserve railroad ties wouldn't leach into the garden soil. Concrete blocks would work, or perhaps some type of untreated wood.

Being built on a cement pad could create drainage problems in such a shallow bed. Making it deeper might help to avoid that. Just a couple of suggestions.

[LindsayArthurRTR]

and maybe adding gravel on the bottom.

[Gary350]

Check with your local hardware or equipment rental company you can rent an electric jack hammer pretty cheap. If you rent is on Saturday at closing time they let you keep it all weekend for the price of only 1 day if you return it at opening time on Monday. Tell them what you are braking up they will suggest the correct cement braking tool for the job. The hardest part of operating a jack hammer it moving it to the next spot once you have busted the cement where you just finished hammering the jack hammer is heavy. I usually just drag it back a few inches, stand it up and hammer there. Another tip, once the tool brakes the cement stop hammering no point in letting the tool go in deep it just makes it hard to pull out. Some rental places have a light duty and heavy duty jack hammer. It light duty is a tinker toy not much good for braking up cement easy and quick.

15 years ago there was a TV show called the Victory Garden, the whole garden is planted on an asphalt parking lot covered in peat moss. You should be able to do the same thing on cement.

[mlangille]

If you plant on the cement keep in mind that it contains a lot of lime
that will affect plant grow. as far as the depth of the soil 12" would be
better for max plant growth.

Just my thoughts

Michael

[garden5]

If you plant on the cement keep in mind that it contains a lot of lime
that will affect plant grow. as far as the depth of the soil 12" would be
better for max plant growth.

Just my thoughts

Michael

I'd have to say that if you are growing anything other than salad greens, a 1 ft. minimum depth would be best.

[applestar]

I think what Gary350 said has merit. Maybe just breaking up the solid concrete into pieces (or even just cracking it in several places) would be sufficient and you won't have to dig them out. The pH issue and the soil depth may pre-determine what you can grow there, but this isn't your only garden bed.

Also, an 8" depth in an open garden is considerably different from an 8" depth in a container.

[Dixana]

As apple kind of said, this is just one 3x4 foot spot in a 10x24 foot garden. I'm not worrying about water pooling as it's one area, has a hole in the middle, and my soil is very sandy (and the hubby cut big lines in it trying to cut it apart too).

What I am wondering is if roots will be affected or find there way around. I havebeans planted in it right now, in only the 4 inches of soil that was on it before I found it. They are only a few inches from the edge but doing very well despite it.
I should have mentioned adding 8 inches of soil would bring the bed 12 inches over the cement too
I also didn't know until I checked that railroad ties are treated with creosote so we're looking at other *cheap* options.
I'm starting another thread on that ideas would be helpfull...