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Timber raised garden bed with herbs growing in it.

Overview

There are a lot of advantages to having a raised garden bed to grow your fruit and vegetables. These include less weeds, more growing space, less soil erosion, better water retention than sandy soils, and better drainage than clay soils. We'll show you how to build a raised garden bed with sleepers, including tips on how to build your supports and how to prevent water run-off.

Steps

1Choose the right location

Before you decide where to build your raised garden bed, consider how much sun, shade and wind it will get. The choice of location will also depend on the types of plants you want to grow as well.

2Measure for the first support post

When you're building your raised garden bed up against a wall, take into account the thickness of the sleeper that will be attached to your support posts. Hold the sleeper up against the wall and mark it off. From that line, mark the width of the sleeper on the wall. Repeat this process for the other end of the raised garden bed.

3Measure for the middle post

Once you've marked out where your end support posts will be, use the tape measure to work out the halfway point between them. Mark that spot on the wall with the pencil.

4Mark the lines for the support posts

At both ends of the garden bed, use the spirit level to mark straight lines on the wall, where the edge of the support posts will be. Measure and mark, half the distance of the width of the sleeper either side of the centre line. Use the spirit level to draw the two straight lines.

5Mark the height of your garden bed

Use the spirit level to mark a straight line across the wall for the height of your garden bed.

6Measure and cut the support posts

Measure the distance between the ground and the where the top of your garden bed will be. Transfer this distance onto the sleeper. Put on your safety equipment and use the circular saw to cut the wood. Cut two other posts so they're the same length.

7Mark for the holes in the support posts

Depending on the length of your support posts, you may need to drill two or three holes in them. Mark out where you would like to drill these holes, making sure they're in the middle of the post. 

8Drill the holes in the support posts

Use the spade drill bit to partially drill the holes in all the support posts. This will allow you to countersink the dynabolt. Change drill bits and drill all the way through the support posts

9Secure the posts to the wall

Hold the post up against the wall, flush with the lines you've marked for them. Use the hammer drill to drill a pilot hole into the wall. Remove the post and finish drilling the holes in the wall. Repeat this step for the other posts.

10Attach the supports to the wall

Place the support posts against the wall. Pull the sleeve on the dynabolt back and insert it through the posts. Use the ratchet to secure the post to the wall. Repeat this to secure all of the support posts.

Person using ratchet and bolt to secure support post against the wall.

11Measure for the length of the sleepers

Measure the distance between the ends of the support posts. Mark this distance out on your sleepers. Put on your safety equipment and use the circular saw to cut the sleepers to size. 

Person measuring length between two support posts.

12Attach the sleepers to the support posts

You will need someone to help you attach the sleepers to the supports posts. Line-up the sleeper so that it's flush with the ends of the support posts and level with the top of them. Pre-drill a hole through the sleeper. Secure the sleeper with a batten screw. Repeat this process for the other end of the sleeper. Then secure the sleepers to the support post with batten screws into each post. Repeat process this to attach the second sleeper.

Person drilling timber sleeper to timber support post against the wall.

13Dig the soil out for the bottom sleeper

Using an off-cut from the sleeper, measure how deep a trench you need to dig to be able attach the bottom sleeper. Use the shovel to dig the trench. Attach the sleeper following the process in Step 12. 

Person drilling bottom sleeper to support post.

14Dig the trenches for the side and front sleepers

Use the shovel to dig the trenches so that they're deep enough for the side and front sleepers.

Person securing bottom sleep to support post.

15Cut and attach the end pieces of the garden bed

Once you've cut your end pieces to size, pre-drill a hole in the top of one of them and secure it to the bottom sleeper. Use the spirit level to check that its level. If necessary push or remove sand from under it. Secure the two other end pieces in the same way. Repeat this process to attach the end pieces at the other end of your garden bed.

Person securing middle sleeper to support post.

16Dig the holes for the front support posts

Before you start digging, check that there are no water, gas or electricity pipes below. Dig the hole for the support posts at either side of your raised garden bed. Make sure the hole is half the depth of the posts you're sinking and that the front supports are in-line with the back supports. Leave a gap of between 50 to 100mm between the top of the support posts and the top of the garden bed.

Person digging hole.

17Attach the front supports to the side sleepers

Line up the front support with the edge of the side sleepers. Pre-drill two holes into each sleeper. Use batten screws to secure the front support to the side sleepers. Repeat this process to attach the other front support to the side sleepers.

Person drilling top sleepers into support post.

18Measure and cut the front sleepers

Measure the distance between the ends of the front support posts. Mark this distance onto your sleepers. Put on your safety equipment and use the circular saw to cut the front three sleepers.

Person securing middle sleeper to support post.

19Secure the front sleepers

Have someone help you hold the sleeper so that it's flush with the ends of the support posts and level with the top of the raised garden bed. Pre-drill a hole in one end of the sleeper and secure it with a batten screw. Repeat this process at the other end of the sleeper. Use two batten screws to secure each sleeper at each end. Attach the two other sleepers in the same way.

Finished wooden raised garden bed with no soil or plants in it yet.

20Check the garden bed is square and level

Use the set square to make sure the corners of the garden bed are square. Use the spirit level to make sure it's level. Make any necessary adjustments to make sure they are.

Person using L-shaped metal ruler to check angles between sides of raised garden bed they're building.

21Concrete in the front supports

Follow the instructions to mix the concrete in a wheelbarrow. Shovel the concrete mix into the hole around the front support posts. Add enough so that it's around 100m below the soil level. Let the concrete set and backfill the hole with soil.

Person shovelling cement into a hole.

22Waterproof your garden bed

To prevent the soil and water from leeching out of your garden bed, use corflute or black plastic to line your bed. Cut the corflute or black plastic to size and use galvanised clout nails to keep them in place.
Person securing black plastic lining to sides of DIY raised garden bed.

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More D.I.Y. Advice

Health & Safety

Asbestos, lead-based paints and copper chromium arsenic (CCA) treated timber are health hazards you need to look out for when renovating older homes. These substances can easily be disturbed when renovating and exposure to them can cause a range of life-threatening diseases and conditions including cancer. For information on the dangers of asbestos, lead-based paint and CCA treated timber and tips for dealing with these materials contact your local council's Environmental Health Officer or visit our Health & Safety page.

When following our advice in our D.I.Y. videos, make sure you use all equipment, including PPE, safely by following the manufacturer’s instructions. Check that the equipment is suitable for the task and that PPE fits properly. If you are unsure, hire an expert to do the job or talk to a Bunnings Team Member.