How to build raised garden beds | B&Q (2024)

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Raised beds are perfect for growing flowers and plants, as well as fruits and vegetables. For ease, why not buy a pre-made raised bed here? But if you’d prefer to make your own, it’s a simple job suitable for any DIYer.

This guide takes you through the process. It lists the materials and tools you’ll need and gives you a step-by-step guide on how to build raised garden beds.

  • Materials
    - 2ft metal reinforcement bars (rebars) x 12
    - W220mm x T45mm timber planks cut into 2.4m lengths x 2
    - W220mm x T45mm timber planks cut into 1.2m lengths x 2
    - Exterior woodcare
    - Landscaping fabric
    - Stones or coarse gravel
    - Compost
  • Tools
    - Stakes and string
    - Tape measure
    - Pencil
    - Hand saw or mitre saw
    - Workbench
    - Rubber mallet
    - Paintbrush
    - Staple gun

Follow the step-by-step instructions below to make a 2.4 x 1.2m raised bed using timber planks. Adjust the plank lengths accordingly if you need to make a smaller or larger bed.

Step 1: Choose your location

The ideal place to locate a raised garden bed is an open area with plenty of sunshine and good drainage. Placing it near a hedge is good for airflow, but make sure there are no overhanging tree branches that will stop rainwater from hitting it.

Step 2: Measure and mark the area

Use a tape measure to plot the area for your raised bed. It will be 2.4m x 1.2m. Mark the four corners with a wooden stake and tie string between them.

Step 3: Cut the timber

Carefully measure your lengths of timber. You’ll need two 2.4m lengths and two 1.2m lengths. Place them on a workbench and cut them to size using a hand or mitre saw. While cutting, take safety precautions, such as wearing safety goggles, a dust mask, and gloves.

Step 4: Assembly

Once the timber has been prepared, lay the four planks flat on the ground, in their position, with their inner corners touching.

Next, stand one of the long planks on its side. Then, using a rubber mallet, hammer a piece of rebar a few inches into the ground one foot from each end of the plank to support it. Repeat the process for the short sides, using one rebar in the centre of each. And then, put the other long plank into position in the same way.

Once all the planks are in position, reinforce the frame by hammering the rebars into the ground, so only 6-10 inches are showing.

  • Long sides: hammer in the two rebars already in place, then add two extra rebars 2ft apart.
  • Short sides: hammer in two pieces of rebar a foot from either end, then remove the one you placed in the centre.

How to build raised garden beds | B&Q (5)

Step 5: Prepare for planting

As the raised bed will be subject to all weather conditions, we recommend painting it with wood stain, oil, varnish, or preservative before filling it. Also, line the inside with landscaping fabric, using a staple gun to attach it to the wood.

Next, spread a layer of stones or coarse gravel in the bottom to help with drainage, then fill it with a suitable compost, depending on what you plan to grow.

Your raised bed is now ready for planting!

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Rough Sawn Treated Whitewood spruce Stick timber (L)1.8m (W)100mm (T)22mm(13)£6.97£3.87 / m

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Smooth Planed Round edge Treated Whitewood spruce CLS timber (L)2.4m (W)38mm (T)38mm CLST01(14)£9.27£3.86 / m

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simpa 20mm Polar Ice Chippings Bag 20kg(1)£19.99£1.00 / kg

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Blue Slate Decorative chippings, Large Bag, 0.3m²(63)£11.00

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How to build raised beds with sleepers

Railway sleepers are another popular material for building raised beds.

First, cut them to length using a circular saw, then place them on the ground, building them up to two or three layers to get your preferred height. Then, secure the sleepers to each other using stainless steel timber screws. You can then paint, line, and fill the bed as described in step 5 above.

How to build raised beds from decking

If you’ve got excess timber decking left over from a project, you can also use it to construct a raised bed. Choose your size depending on the lengths of decking you have. As deck boards are narrow, you’ll need to build up two layers to raise the height of the sides.

First, cut the decking to size and build the first layer by butting up the ends and screwing them together using deck screws. Then do the same with the second layer.

Next, place the two frames into position, one on top of the other, put an offcut of wooden batten in each corner and screw both parts of the frame to them. Finally, line and fill the bed as described in step 5 above.

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Tips

  • When choosing wood, look for untreated timber that’s safe for growing plants. Avoid using pressure-treated wood, as it may contain harmful chemicals.
  • Make sure the raised bed is level to prevent uneven water distribution. Use a spirit level to check.
  • Consider adding a drip irrigation system to make watering easier.
  • To extend the growing season, consider adding a cover or hoop house to protect the plants from cold weather.
  • Easi Railway sleeper (W)195mm (L)1.2m(3)£26.50

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  • Tarmac 10mm Gravel, Large Bag(101)£4.00

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  • Claber Rainjet Terraces Irrigation kit(8)£65.00

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  • Claber Plastic Water pipe (L)2m (Dia)6mm(5)£25.00£1.25 / m

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Easi Railway sleeper (W)195mm (L)1.2m(3)£26.50

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Tarmac 10mm Gravel, Large Bag(101)£4.00

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Claber Rainjet Terraces Irrigation kit(8)£65.00

View product

Claber Plastic Water pipe (L)2m (Dia)6mm(5)£25.00£1.25 / m

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Safety first

When cutting wood, always protect yourself from flying debris, sawdust, and splinters by wearing safety goggles, a dust mask, and gloves.

FAQs

To help with drainage, put stones or coarse gravel on the bottom of a raised bed.

A raised bed should be at least 20cm deep. However, the ideal depth will depend on what you’re growing. For example, root vegetables need at least 60cm.

Hardwoods are best for raised beds because they are naturally weather resistant. However, you can also use other untreated woods, decking or railway sleepers. Avoid pressure-treated wood as it contains chemicals that will kill plants.

You can line a raised bed with landscaping fabric to increase durability. However, it’s not a necessity.

We hope we’ve given you the confidence to build your own raised plant bed. But if you’re not ready for that yet, take a look at our ready-made raised bed range.

Why not browse our Gardening Range to see what else you can do to make the most of your garden this summer.

How to build raised garden beds | B&Q (2024)

FAQs

What do I put on the bottom of a raised garden bed? ›

Start with a layer of landscape fabric to prevent soil from washing out. Above this, a layer of gravel or small stones can aid in drainage. Then, fill the bed with a mix of topsoil, compost, and other organic matter. This layered approach ensures good drainage while providing a nutrient-rich environment for plants.

How to calculate amount of soil needed for raised garden bed? ›

To calculate:
  1. Measure the length, width and height of your bed. (Unless the boards are very thick, don't worry about inside/outside measurements.) ...
  2. Multiply all the measurements together: 6 x 3 x 1.4 = 25.2 cubic feet.
  3. Divide the answer by 27 to get the number of cubic yards.

How do I maximize my raised garden bed? ›

Raised beds help maximize garden space because you don't have to use space for walkways. Planting in squares or rows may look neat, but it uses space less effectively. Instead, arrange your plants in triangles. By doing so, you'll be able to fit more plants into the same space.

How many bags of soil do I need for a 4x8 raised bed? ›

As a rule of thumb, a 4'x8' raised bed that is 6 inches deep requires approximately 8 bags of soil while a 4'x8' raised bed that is 12 inches deep requires approximately 16 bags of soil.

What layers should a raised garden bed have? ›

How to fill a raised garden bed in six simple steps
  • Step #1: Prepare your garden bed. ...
  • Step #2: Add a drainage layer. ...
  • Step #3: Add a layer of ordinary garden soil. ...
  • Step #4: Add some premium potting mix. ...
  • Step #5: Water the soil to help it settle & add some mulch. ...
  • Step #6: Start planting!
Jan 30, 2023

Why put cardboard in raised beds? ›

It acts as a physical barrier to block out pernicious weeds. Usually, 2 – 3 layers of cardboard will suffice, though you may want layers in more weed-prone areas. The damp environment created by the cardboard is conducive to earthworms and other beneficial soil microorganisms.

Should I put landscape fabric under raised bed? ›

The fact is, landscape fabric is not a necessity if say, you want to control weeds because the confined space makes it easier to control weeds. But, you can use landscape fabric as a raised bed liner for other reasons, such as preventing soil erosion or improving the life of the raised bed itself.

Should I put rocks in the bottom of my raised planter? ›

Adding rocks to the bottom of a raised bed makes it challenging to amend or improve the soil over time. It restricts access to the lower layers and can impede the addition of organic matter or nutrients. Over time, rocks will get mixed in with your raised bed soil, not cool! Rocks are expensive and heavy!

How many bags of soil do I need to fill a 3x6 raised bed? ›

To fill a 3x6 bed with 10" sides, you will need 15 cubic feet of blended soil. To create the blend, use the following quantities: 9 cubic feet of topsoil (9 20-quart bags) 4.5 cubic feet of compost (4.5 20-quart bags)

How deep should soil be in a raised bed? ›

A raised bed does not always require a significant depth for it to be effective. They should have at least 8 inches of soil depth to accommodate the root systems of plants, because the majority of plant roots require 6 – 8 inches of soil for healthy root growth.

How deep should soil be for raised vegetable beds? ›

A raised bed does not need to be very deep to be effective, but the surface underneath your garden bed affects which depth is right. In general, eight inches is a good minimum depth for raised garden beds.

How deep should a raised bed be for tomatoes? ›

Tomatoes should ideally be grown in a raised bed that's at least 15 to 18 inches deep. Many of my clients in Houston are successfully growing tomatoes in 12-inch deep raised garden beds, but their plants tend to be a little stunted compared to plants in deeper beds.

What vegetables grow well together? ›

Which Vegetables Grow Well Together?
VegetableCompanion PlantDon't Plant Together
PeasBeans, carrots, corn, cucumbers, radish, turnipGarlic, onions
PotatoesBeans, corn, peasTomatoes
SquashCorn, melons, pumpkinsNone
TomatoesCarrots, celery, cucumbers, onions, peppersCorn, potatoes, kohlrabi
11 more rows
Jun 26, 2021

Is it cheaper to buy or build raised garden beds? ›

Store-bought raised garden beds come in a variety of sizes and styles, but can be pricey. For those interested in raised bed gardening without the expense, these DIY raised garden beds with step-by-step instructions can be built in a few hours and often for a fraction of the cost of store-bought kits.

How deep should a raised garden bed be? ›

A raised bed does not need to be very deep to be effective, but the surface underneath your garden bed affects which depth is right. In general, eight inches is a good minimum depth for raised garden beds.

Should I put rocks in the bottom of my raised garden bed? ›

Well-structured soil with plenty of organic matter already provides adequate drainage in a raised garden bed. Rocks are not essential for achieving proper drainage and can even hinder it. Limited soil depth. Placing rocks at the bottom of a garden bed reduces the available soil depth for plant roots to grow.

What are the best materials to build a raised garden bed? ›

Build your raised bed with a decay-resistant type of wood, such as cedar, black cherry, oak (bur, chestnut, post, white), black locust, Osage orange, or redwood. (Source: USDA Forest Products Lab) Use a non-wood material such as stones, concrete blocks, bricks, or synthetic lumber.

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