Recycled Planter for the Greenhouse

Converting an old plastic drum into a greenhouse planter
Finished Planter with Shallots Growing in it

Finished Planter with Shallots Growing

This is how I went about turning a plastic barrel into something useful. I’m always struggling to find enough pots and trays to sow and grow on seedlings, so I’m hoping this system will make life easier. Seeing lots of different ideas on the internet, I decided to go for this setup. Constructed using treated roofing timber the unit cost is pretty low, and it should last a few years.

plastic barrels for my greenhouse planter

Plastic barrels

recycled barrel planter ready to use

Planter ready to use

A friend of mine gave me a few of these barrels when I was looking to build my chicken plucker, having some left over I decided to recycle one into a planter for the greenhouse. The idea is that it can double up as both planter and staging. Being used to sow seeds or grow smaller crops and portable enough be moved outside during the summer months if required.

Parts List

  • An old 200 litre plastic barrel.
  • 2″ or 50mm square treated wood.
  • 5 x 80 mm Wood screws for wooden frame.
  • 5 x 30 mm Wood screws to attach barrel to frame.

First Stage

Preparing the plastic drum

Cutting the barrel in half

Depending on what the barrel was previously used for, it may be a good idea to clean it before starting to work with it.

The barrels that I had were used to transport antifreeze, so I just rinsed out a few times with clean water.

Once cleaned I marked a center line with an indelible marker pen. Usually there is a centreline on the top and bottom from the moulding process.

Then using a fine toothed wood saw carefully saw along the marked centreline.

cutting the plastic barrel in half

Build Stage 2

Build framework to hold the half barrel

Make the frame and attach to the half barrel

Measure the barrel and make a rectangular frame, attaching with a screw in each corner

Wooden frame for recycled barrel planter

Then using the 5 x 30 screws, attach the wooden frame flush with the sawn edge of the barrel half.

Half barrel screwed to frame - close up

This picture shows the barrel half screwed to the frame and turned over, ready for the support framework to be attached.

Half barrel screwed to frame - close up

Build Stage 3

Make the leg framework to support the planter

Building the leg framework for the barrel planter

I’ve used basic butt joints in the construction of the framework. Held together with the 5 x 80 wood screws.

The height of my barrel planter is 80cm as I want to use the shelf under the barrel for seed trays. Also at this height it can be easily moved without bending over, which is great for my back.

Wooden framework for recycled barrel planter

Cut 4 legs to achieve the required height. Then cut 2 long and 2 short braces and screw together.

Finally, cut 8 45° braces and attach as shown in figures 5 & 6. I’ve added the center brace shown in figure 6 as a support for seed trays.

Framework assembled - recycled barrel planter
Wooden bracing for recycled barrel planter
Wooden framework for recycled barrel planter with bracing

Final Stage

Finishing off the barrel planter

Adding drainage holes

One last thing to do before using the planter is to drill some drainage holes in the bottom of the plastic barrel.

I used a 16mm wood drill, producing 3 rows as shown

recycled barrel planter drainage holes

Here’s the finished planter in the greenhouse ready to be filled with compost and planted up.

Finished recycling plastic drum as a planter project

Using The Barrel Planter

Planting Shallots in the finished planter
Recycled barrel planter slates over holes

Start by covering the drainage holes with some old broken roofing slates.

Then fill will compost and plant the shallots.

Three weeks later it looks like this

Finished Planter with Shallots Growing in it

I’m really pleased with the outcome of this project. Will definitely be building more of these recycled barrel planters.

Barrel Planter Update 2022

Is it still being used?

I’ve made three of these now and find them excellent for certain crops.

Last year in 2021 we had the best crop of garlic for years from one planter and the shallots were also good.

Harvesting Shallots

Harvesting the shallots

The shallot harvest

Not a bad crop at all

So easy to harvest and a good crop from such a small area, very pleased with the result!

This year we are starting by planting some early white onions sets

They are already off to a good start

planting oinion sets in barrel planter

Onion sets just producing shoots