Rised flower beds - Can they be built on top of concrete?

[marianne]

hi there, my friend has a concrete yard outside her flat and would like to construct a raised flower bed on top of it. is this possible? (?drainiage etc.) And what would be the best materials to use? She would like to grow grass in it so she can use it as a grazing area for her two guineapigs and her tortoise! any advice much appreciated. :laugh:

[glyn1206]

Yes! If you're building it of brick leave some upright joints (perpends) without cement ,(one course is enough) to create weep holes,then cover the base with stones,gravel or something similar,add some lanscaping fabric on top of this before adding soil,the fabric will prevent the soil from washing down into the gravel and blocking the weep holes.
One word of caution though,there may be some slight staining of the concrete from the weep holes it may also be worth lining the part above the fabric with some polythene to stop the soil marking the brickwork