Building a Self Watering Raised Garden Bed

I am 99% finished with a weekend home improvement project and it is only Thursday!  Just don’t ask what weekend I started on.  😉

Shae and I have been talking for a while about building some kind of raised garden/flower bed in our backyard.  I wanted something tall but affordable.  Shae wanted low maintenance.  Here is the almost finished product that has been erected in our backyard.

A view from the inside of the ‘L’

and a view from the alley.

From the Beginning

Every project of ours starts with a written plan.  We often go through several iterations of a design before settling on ‘the one’.  The first proposal was a simple rectangle and the site location for it was a completely different part of our backyard.  It was only about a foot tall and made entirely from cedar.

Of course that didn’t really meet any of our specs.  Cedar is an expensive wood, at least when compared to pine.  The planter was only a foot tall and it wasn’t self watering.  There had to be a design that would meet all of our requirements and eventually we started toying with an L shaped hybrid design that incorporated low cost treated, stained pine with galvanized sheet metal.

Several revisions later and we had our bill of materials.

 

Menards was running an 11% rebate sale, that we took advantage of.  We also rented one of their trucks ($22.50) for 75 minutes from when you leave the outdoor yard.

We unloaded all of the material minus the dirt into our garage for the evening.  I posted the below picture to Facebook and asked friends to guess what I was building.  People were very creative in their guesses, although most were spot on that it had to do with gardening.  That night I started building the frame in the garage.

Saturday morning, Shae helped me drag the frame out of the garage and put it next to its final resting place.  It was a bit taller than either of us anticipated!

Due to its weight, we decided that I would build the rest of it in place, so we marked out where it would go on the grass.

Then dug out and leveled the ground so the planter would sit evenly.

After dragging the skeleton into place and leveling it, I started fitting the metal panels.

After fitting the first panel, I instantly knew there was a serious design flaw.  My intention was to have the panel hold the dirt in, but with it only being secured at the top and bottom, it was far too ‘bendy’ and easily bowed in and out with the slightest amount of pressure.  To resolve this, I bought three additional stained and treated 2x4s to brace the panels on the outside.  I also had to buy an additional four regular treated 2x4s to replace the ones that had to be used for bracing.

Being able to screw the sides of each panel added much needed rigidity.

 

With the panels in place, I turned my attention to the inside of the planter.  Instead of filling the entire planter with dirt, an expensive and back breaking proposition, we opted to instead build a raised internal floor.  I secured treated 2×4 joists to the vertical 4x4s.

Treated 1x6s were cut to size and installed as planking.  Frugal Boy enjoyed cruising along the inside.

Once all of the floorboards were installed, I grabbed some left over heavy duty plastic from when we lined one of our crawlspaces and carefully placed it into the planter to make a liner.

With the liner stapled to the top of the planter, I cut 3″ corrugated, perforated drainage tube to fit the bottom.

These tubes act as a water reservoir and form a critical part of the ‘self watering’ aspect of the planter.  Of course, you need a way to add water to the reservoir and that is where this handy fill tube comes into play.

We also needed an overflow drainage pipe.  I used a scrap piece of pvc and drilled a bunch of holes into it.

 I cut a hole in the planter side just above the corrugated pipe

and inserted the overflow pipe.

The overflow is on the far side of the fill tube.

All of the piping gets wrapped in landscape fabric to prevent dirt from falling in and filling/clogging up the watering system.

Then it was time to add dirt!  I started with some sand along the sides of the corrugated piping.  I read somewhere that top dirt sitting in water will begin to stink as anaerobic bacteria goes to town.

With the dirt added, the only major thing left was to add the edge cap.  I used treated and stained 2x6s and secured them with screws from the underside to leave an unmarred top surface.

What’s Left?

Besides sowing seeds, something that will have to wait until it gets a bit warmer, the only big item left to complete the project is to add gravel along the perimeter like so.

I am putting down landscape fabric to keep weeds from popping up next to the planter.  Holding that in place is river rock because it is cheap and attractive.  I have to go back to the store for a few more bags of rock.  I also need a PVC cap for the supply tube so mosquitos cannot breed in the underground reservoir.

So there you have it!  Hopefully the self watering system will work by wicking moisture from the reservoir to the root systems.  We should only have to water once a week even during the hottest days of summer.

Shae has been deciding what she wants to plant and already has a few ideas.

Leave a comment with what you would plant!  Who knows, maybe we’ll try it out ourselves.