Introduction: Make a Garden Planter From Decking

Hello, and welcome to my 2nd published Instructable, children! Today we're going to make a planter from offcuts and inexpensive timber.

I've always been interested in growing some vegetables in the garden, but, as I'm sure some of you can testify, there's always another project that demands attention. Recently I signed up for a fantastic offer from the BBC and got some free seeds, which has finally spurred me on to grow my own grub - I don't think the seed offer is still running, but you can have a look at the BBC Dig In mini-site at

Our English country garden is pretty small and we didn't have any spare border for veggies, so we needed a planter. I couldn't find one big enough for less than £60, so I roped my old man into helping me build one.
What follows is an account of our magical journey to garden planter ownership... Read on and maybe one day you too could be a planter owner. Imagine that.

SAFETY NOTES: This Instructable involves the use of power tools, so if you are a mere youngling, you should get an adult involved. Nobody is going to grow back a severed arm by eating more vegetables...

Step 1: What You Will Need:

Tools We Used:

  • A hammer, for showing nails who's boss.
  • A screwdriver.
  • A chop saw - Hassan Chop!
  • A jigsaw, for the cut outs.
  • A circular saw for the base slats.
  • A couple of 'G' clamps for holding it together.
  • A staple gun for attaching the plastic lining.

Materials We Used:

  • Decking planks (2 x 4800mm long and 1 x 3600mm long).
  • 2 lengths of treated timber (19mm x 32mm x 2400mm).
  • 6 lengths of timber offcuts (30mm x 50mm x 500mm).
  • 10 decking plank offcuts (at least 630mm in length).
  • 48 self tapping decking screws.
  • 20 clout nails.
  • Polythene or pond-liner or some other plastic (for lining the inside of the planter).
  • 350 litres of multi-purpose compost.
  • Broken garden pots or stones to layer underneath the compost, to aid drainage.

We managed to get most of our stuff at discount prices from Wickes - we bought damaged decking planks for about half price and damaged compost for £1.99 a bag. It came repackaged in strong polythene, which we then used for the lining. Most garden centres or DIY shops will have some goods damaged by careless forklift drivers which they'll be selling cheap - have a look around at the back or ask someone. It's definitely worth it - our planter only cost £32 (not counting the hardware and offcuts we already had). That includes filling it with compost and, thanks to the BBC, the seeds we'll be planting.

Step 2: Cutting List

Make a cutting list of the parts you need to make the planter - then you can work out what you need to buy and what you can use from the shed.

  • 6 side pieces (1400mm lengths of the decking plank).
  • 6 end pieces (630mm lengths of the decking plank).
  • 6 legs (30mm x 50mm x 500mm).
  • 10 slats for the base.
  • 6 lengths of timber to make a baton to hold the base slats (19mm x 32mm x Various).

TIP FROM MY DAD: Measure and cut a 'master' piece, then use it as a template to cut the rest of the pieces. That way, even if it's a little bit out, then all the pieces will still turn out the same. It's more important that it has it's own internal integrity rather than being mathematically accurate.

Step 3: Making It Fancy

With a tiny bit of extra effort in a couple of places you can make the planter look more professional. Before constructing it we chamfered the edges of the longer side pieces, this was done by setting the chop saw at a 45 degree angle and starting the cut 12mm from the edge (our decks were 30mm). You can see the outcome in the images.

TIP FROM MY DAD: Chamfer the bottoms of the legs to stop the wood splitting. I had a go at this on an offcut and made it look like a stake that could kill a vampire! My dad just eyeballed all six legs and they came out perfect. I hate to admit it, but sometimes he's right about stuff.

Step 4: Main Construction

Now you've got your pieces cut, you've made the edges look fancy and it's all lying there ready for construction...

A. Get your clamps ready, then lay out the first corner and leg. Take a long side, a short side and a leg and place them together as shown in the image (1). This is upside down to the way it will finally sit. The small off-cut under the leg is to set the leg slightly below the top of the planter so you can't see it from the side. See image 1.

B. Clamp the parts together so that you can still get two screws into both decking parts. See image 2 and 3.

C. Screw the corners of the decking to the legs. There should be a screw in each corner of the decking planks. See image 4 for approximate screw positions.

D. Move on to the next corner - don't forget to offset the leg with the off-cut. See Image 5.

E. Finish all four corners in the same manner - see Image 6.

F. Screw down all the side pieces - fit them up first to see which order they should go depending on any warped pieces. See Image 7 for approximate screw positions and Image 8 showing all side pieces attached and the planter turned right side up.

G. Turn the planter upside down again - legs in the air. Measure the space between the corner legs on the long side, in our case this was 1240 mm. Half this number and measure and mark on the bottom of the bottom side piece on both sides. This is the centre point at which you want to attach the middle legs. Remember to offset these using the off-cut and attach using six screws. See image 9 for a shot of the planter with middle legs attached.

H. Cut the thin pieces of timber to make the slat supports by measuring the distance between each of the legs. You'll need two end pieces and then four side pieces for between a corner leg, the middle leg and the other corner leg; on each side. Much simpler than that sentence makes it sound! See Images 10-14 for shots of the slat supports in place. We had a piece left over which was long enough to span the planter, so we added an extra support across the middle - it's not necessary and serves no structural purpose, but you might as well use the wood if it's left over.

Step 5: The Base Slats - Construction Phase Two

In the first image below you can see a planter we made previously. It had very thin base slats and one has broken. The planter in this Instrucable will be filled with a lot of compost and will be very heavy so the slats need to be a bit more heavy duty. We used offcuts of decking we had in the shed. They are approximately 30mm x 140mm x 630mm.

I. Cut 10 x 63cm slats from the offcut decking planks. Cut one measured piece and then use it as a template for the others. Test fit each one as you go along. See images 2 and 3.

J. Cut out the corners on two slats, so that they fit around the legs in the corners. We drew around an offcut of the legs and made two cuts for each corner with a jigsaw. See Image 4 for a view of the finished cutout.

K. One slat will need two cutouts around the middle legs (we were really lucky and the cutout we needed was exactly the same as the corners, but it may end up in the middle of the slat and need a three side cut with jigsaw). See Image 5 for our finished cutout and Image 6 for a view of the half-size slat.

L. Unless you are really lucky (or work out the initial dimensions based on the slat width) there will be one slat that needs to be narrower than the others to fill in the gap. We cut one slat in half with the circular saw to plug our gap.

M. Place all the slats into the base (see Image 7 for a view of the halfway point).

N. Bask in the glory of completing the woodwork part of construction! See Image 8.

Step 6: The Final Steps

Now we've got the wooden construction finished we need to drill drainage holes, line the inside and fill it with compost.

O. Drill some holes in the base of the planter. You want to hold some water, but it needs to be able to drain away as well - worst case scenario your vegetables could rot.

P. The damaged compost bags we bought came repackaged in larger sacks (Image 2).

Q. We slit the sides and stapled the plastic to the inside of the planter. Roll the top of the plastic over and staple it about 2cm below the top of the planter. Take extra care around the legs.

R. Place broken pots or large stone in the base for drainage (see Image 4).

S. And now for a bit of maths to find the volume of the planter, and therefore how much compost we need... We can find the volume (v) by multiplying the length (l), the width (w) and the height (h).

lwh = v

So, in centimetres:

(140 x 63) x 42 = 370440

1000 cm3 is equivalent to 1 litre in volume.
So 370440 cm3 is equivalent to approximately 370.5 litres.
Our bags hold 75 litres, so we needed five to fill the planter.

T. And that's all folks! It's ready for planting... We started some carrots on the window sill this week as it's still a little bit cold to plant them outside straight away (May in the UK is a bi hit and miss). We'll transfer them in a few weeks when they are more established.

U. Have a look at the next step for some more planter ideas...

Step 7: Other Ideas (A Showcase)

Have a look at the images below for other ideas - these are all the planters my Dad made for our garden. The last one is the pièce de résistance with its integrated benches and pot stand.

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