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How to make a contemporary raised bed

You will need

For the foundation:

Builders' rubble (two wheelbarrows full), such as Type 1 Roadstone, available from your local builders' merchants

Postcrete (5 x 20kg bags)

For the walls:

Medium concrete blocks (64 blocks of 450mm x 215mm x 10mm)

Mastercrete cement (2 x 25kg bags)

Sharp sand

Building sand

PVA admix (1 x 5l tub)

Finishing touches:

Untreated oak sleepers (10 linear metres; we used half sleepers, which are half the depth)

Blended loam or topsoil

Masonry paint

Do it: all year round
Takes just: two weekends (including drying time)

Overview

Raised beds are a great way to grow plants, improve soil conditions and resolve tricky design challenges in the garden. You can create the conditions that ensure plants thrive, and custom build it to suit your own garden.

This raised bed is made from concrete blocks and topped off with timber sleepers to provide extra seating space, invaluable in a small garden.

With basic DIY skills, plus a couple of spare weekends, you'll soon have a 2.2m x 1.4m raised bed that will provide space for ornamental and edible plants for years to come. Although the work itself doesn't take more than two days, plan ahead as you'll need to factor in two 24-hour drying periods.

The end result has a calm planting scheme of box balls, lavender and a multi-stem amelanchier. It frames the view of the garden beyond.


How to do it

Step 1

1

Mark the bed shape by laying the blocks on the ground. Dig a shallow trench, 30cm wide and deep, for the foundation the blocks will sit on, and fill with a 20cm layer of rubble. Tamp down thoroughly with your heels.


Step 2

2

Top up the foundation with a 10cm layer of Postcrete and spread out using a shovel. Use a spirit level placed on a straight board to check the surface. When it's thoroughly level, water the Postcrete thoroughly.


Step 3

3

Set the blocks on a bed of mortar. Start building at one corner of the foundations, using mortar to stick the bricks together. Build the other corners level, then the walls, checking they're straight with a spirit level.


Step 4

4

Once the blockwork has set (after 24 hours), make up the render (two parts sharp sand, 2 parts building sand, 1 part mortar). Add 600ml PVA adhesive per barrowful. This makes the mixture easier to work with.


Step 5

5

Wet the blocks using a watering can. This stops the dry blocks from sucking the water out of the render. Apply 5-10mm of render using a plastering trowel. Keep wetting the blocks so the render goes on, and stays on, easily.


Step 6

6

Once the render is fully dry (after a further 24 hours) make the edge with half sleepers. Secure them by screwing offcuts of sleeper inside the blockwork. Get someone to hold the offcuts in place while you drill.


Step 7

7

Paint the render using an exterior-grade masonry paint (this is the best type for using on rendered blockwork). A litre of paint will cover around 6 sq m of wall. You may need two coats.


Step 8

8

Fill the bed with a soil/compost mixture such as blended loam or make your own mix using 2-3 parts garden soil, 1 part sand and 1 part well-rotted compost. Add more sand if you have clay soil.




Discuss this project

Talkback: How to make a contemporary raised bed
Your comment will appear after a quick registration step

Steviebhoy 28/03/2014 at 22:53

What is the approximate cost?

Dovefromabove 29/03/2014 at 08:05

How long is a piece of string?  

If you're going to buy everything new from the builder's yard you can price the materials up online  http://www.wickes.co.uk/gardens/icat/gardens/ (other builders' merchants are available)

or you can visit local deadstock auctions, scrap yards and use ebay and Freegle and other such sites and probably build one for virtually peanuts