Any info about building raised beds!

[blue411]

Im all set to build my own beds, but i may have to put them onto a graveled area of my garden, so my question is do i need to put a membrane of sorts down first with holes in it ? and if im able to build onto my grass do i have to do the same thing?
Thanks

[Mikey]

Im all set to build my own beds, but i may have to put them onto a graveled area of my garden, so my question is do i need to put a membrane of sorts down first with holes in it ? and if im able to build onto my grass do i have to do the same thing?
Thanks

How deep are they going to be, and what do you intend filling them with. If its the grass option, I would skim the top layer off, fork the ground below to improve drainage, turn the grass upside down, and fill with whatever.

[blue411]

They wont be more than 15 inch deep as im a newbie and dont want to "over face" myself!!!
But pots and troughs just arent enough anymore, i started with pots etc... to see if i could actually manage to grow anything and i have had loads of success so off i go!!!

[Kristen]

Putting them on top of a path doesn't sound very good to me - the plants are going to need a good depth of soil. My thinking about a raised bed is they get X depth of the original soil and about 1/2 X more on top!