Garden Projects and Ideas - Gardening Forums

Raised Bed over concrete

Need advice about building a raised garden bed, double-digging or installing an irrigation system? This is the place to find the help you need!

Raised Bed over concrete

Postby ordonyez » Jun 20, 2013 8:13 pm


New to the forum. I just built a new deck and want to build an 8x8 raised planter Bed over an old 8x8 slab that was previously used for a hot tub. It will be 2' high and the outside walls built with 6x6 PT lumber with vertical fence boards to match the deck.

The planter will be used to house an small pre-fabbed pond and some plants and flowers as a nice water feature.

My largest concern is drainage. I was thinking about putting a few inches of gravel and then filling with soil? Will this work. I also was thing of adding weeping holes drilled out the side of the 6x6 to help with water drainage as I dont want a bath tub after a large rain.

Any suggestions would be helpful.
User avatar
Posts: 1
Joined: Jun 20, 2013 8:05 pm

Re: Raised Bed over concrete

Postby Countryboy » Jun 20, 2013 9:54 pm

That sounds good for drainage. With the caveat that u want as few connections between the draining water and your wood as possible. So one or two big holes would be better than many small ones.

The one thing that I might do differently, to create a fully natural drainage, is to block your bottom side boards up off the concrete slab at least 1/2 to 3/4 of an inch. To keep them away from as much damp as possible.

As long as the very bottom course of the gravel inside is bigger than your gap, none will trickle out.

It sounds like a nice feature. Best of luck! :)
Adopt the pace of nature, her secret is patience.
.....Ralph Waldo Emmerson....

Frank . . ON5a
User avatar
Posts: 886
Joined: Nov 14, 2008 11:29 am

Re: Raised Bed over concrete

Postby conniepr » Jun 22, 2013 9:48 am

This does sound like a very interesting project. I would love to see before, during and after pics. One thing I can think of is... what zone are you in? Because if it gets really cold in the winter, you need to be thinking of the plants planted in the box. Raised beds can leave plant roots vulnerable to a deeper cold than they would experience underground. There are ways to work around that, but... depending on where you live you might (or might not) need to be thinking about this.
User avatar
Posts: 252
Joined: Jul 09, 2010 8:52 am
Location: Zone 3

Return to Garden Projects and Ideas

Who is online

Users browsing this forum: No registered users and 5 guests

Follow Style At Home Online



Latest Contests

more contests