How to build a raised garden bed with sleepers

A good dimension cross section for this type of project is 95mm X 195mm, or 120mm X 240mm.

You will need four individual parts in total for a single layer. As we are creating a rectangular planter, we are using 2 full 2.4m sleepers and 2 halves in this example. For ease you can purchase sleepers pre-cut, both 2.4m and 1.2m lengths are available from our branches and perfect for this project.

Your sleeper bed will work best when you have good drainage directly below it. A 20mm gravel bed over a weed suppressant would allow water to drain away from your plant roots whilst restricting weed growth.

Lay the sleepers on a level section of ground or gravel bed in a rectangular shape, with the narrowest sides on the ground and facing upwards.

Use a minimum of two Spax screws 8x200mm (available to purchase individually or as a pack of 25) at each corner to attach the sleepers together. 105mm of the length of the screw needs to drill into the adjoining sleeper to create a solid connection. Alternatively, you can screw galvanised L brackets to the inside corners to keep them stable.

You will now have a box shape that creates a neat border. Depending how raised you would like your flower bed, you can leave it like this at 7.87 inches above the ground, or for additional height and interest you can add layers. An extra layer would make the total depth approximately 400mm (15.75 inches).

If you would like to add another layer, we recommend individually laying each of the sleepers on top of the box you have created, overlapping the joins as if you are bricklaying. Create one corner, then screw the sleeper parts together through the top layer and into the bottom layer (as demonstrated by arrows in the image below) so they are affixed before adding the remaining sleepers to create the same rectangular shape.

Attach the layers together using 200mm long timber screws, drilling downwards from the top to attach the two layers to each other. Alternatively, you could use brackets on the inside to connect the two layers.

Repeat steps 4 & 5, remembering to overlap the sleeper joins until you have the desired height. Anything over 6 inches in height is sufficient for a raised bed.

Now that you have your raised bed, you can fill it with a topsoil of your choice and start planting. You may want to add bricks or stones at the bottom before the soil to increase drainage. For added protection you can line the beds using a material that is porous to allow excess water to escape,  this also allows access for helpful insects and worms. If you also want to change the appearance of your sleeper beds, you can paint them in a variety of different colours.

To preserve your sleepers further, we would recommend using a treatment for them, such as an exterior wood oil or decking oil, ideally twice a year in Spring and Autumn, especially if they are installed on top of paving.