Underbed for raised garden

Question

We have a drainage / flooding problem where lots of water passes through our garden, from the higher house on our right to the lower house on our left.

I want to put in a raised garden, which has a "base", "under-bed" that allows the water to pass through it, or even to stay in it, but with a good soil layer on top of it, in which the plants grow.

What material should I use? Clay Pebbles? Straw? Mulch? What can be cheap and workable? Is this even a good idea?

Answer 1

• Dig some trenches at about one foot (~30 CM spacing) parallel to each other from the higher point to a lower point.
• The trenches should be about six inches (~15 CM wide)
• line the trenches with landscape fabric or geotextile
• add four inch drain pipe, perforated with a sleeve
• fill with crushed gravel, 5/8 inch or 7/8 inch diameter, without any fine crushed material
• top with another layer of landscape fabric to bring it level to the surface
• build your raised bed on top. For surface vegetables you will need at least one foot (~30 CM ) of soil, better to have two feet if you want to grow root vegetables
• if you have serious water volumes flowing through then where the four inch drain pipe terminates add a french drain which is described here
• drain pipe is available at most hardware and home building centres