I am trying to build a raised flower bed. The bottom base is concrete. I need ideas on how to?

build this raised flower bed so that the water will not sit at the bottom of the base. Also what should the walls be made of. Thanks for your thoughts on this idea

I am trying to build a raised flower bed. The bottom base is concrete. I need ideas on how to?
We built ours out of 4" x4" treated(treated with copper, not arsenic) wood and the excess water comes out between the wood. We used long lag screws to hold them together. We also built some out of retaining wall block which weeps excess water through the blocks quite well. With a concrete base, you could use either and the excess water would just weep out under the bottom blocks or wood.





If you do a google search for "raised bed gardening" you'll get many sites that have information about it and places that sell kits to build them. I've used mine for vegetables and had a bumper crop of tomatoes, cucumbers and squash despite the drought we're having.





I also put earth worms in my beds to help improve the soil since we had used topsoil bought from Lowes that didn't have a lot of nutrients in it.
Reply:I don't think I am understanding. Are you building a flowerbed on a concrete slab? If so, that is going to fry your plants.


Just like lawns fry if there are rocks beneath the surface, the concrete is going to be heated by the sun and cook your garden.
Reply:Ideally you should break up the concrete so that water can drain into the soil beneath the concrete.





Otherwise, you will need to put a layer of gravel or plastic drainage tubing on the bottom of the raised bed. Wall can be made of anything you choose: wood, stone, concrete, bricks.
Reply:You could put in French Drains, which are basically clay pipes that sit at the bottom of the bed, and lead excess water out of it.





If you are careful, and don't over water, you can just treat your bed like a giant pot.





The walls depend on what you are trying to do, and how high you are building the bed. I like concrete blocks, personally, but it depends on your budget and tastes.
Reply:You can build the walls out of whatever you like- wood, concrete block, landscaping block. It sounds like you are building raised beds on an existing concrete slab. If so, make the beds 8-12 inches deep. Water will not sit at the base, it will drain out under whatever materials you use. If you use hollow core concrete blocks, you can fill the cores with soil and grow in them also.





Visit our website for more raised bed gardening ideas at-


http://www.gardening-at-the-crossroads.c...





Good Luck and Happy Gardening from Cathy and Neal!