How to build a wooden planter

Wooden planters are ideal for adding greenery and colour to small spaces, patios, and balconies. You can buy ready-made planters, but making your own is easy! And in this guide, we show you the tools and materials you will need and guide you through the steps required to create your own wooden planter.

This guide gives advice on choosing your wood and deciding on your planter's size. It then explains how to cut and assemble the wood, add drainage holes, and finish the project.

And don’t worry if you’re on a tight budget. You can use repurposed wood as a cost-saving alternative to buying new materials.

Tools you need
As well as timber, screws and sheet plastic (i.e., polythene or pond liner), you’ll need a:

• Tape measure

• Mitre saw or hand saw

• Drill

• Electric screwdriver

• Set square

• Staple gun

• Orbital sander or sandpaper

Step 1: Choose your wood

You’ve got several options for wood, as follows:

• Constructional timber
  Use constructional timber suitable for outdoor use. If using pressure-treated wood, line the planter with plastic to prevent the chemicals from killing your plants. Read our timber buying guide if you need help.

• Sleepers
  Recycled railway sleepers are environmentally friendly and have a naturally weathered look.

• Repurposed wood
  Save money by using off-cuts of decking or even old wooden pallets.

Step 2: How big do you want your planter?

The size of your planter will be determined by its location and how much you want to grow. Use the following as a guide:

• Small planter: 4’ x 2’ (approx. W1220 x D610mm)
  - Fits roughly 12 to 16 plants
  - Using W50 x T47mm timber sticks, you’ll need 8 x 4’ lengths and 8 x 2’ lengths, plus 4 x 4’ lengths of 150mm wide gravel board for the base*
  - Using decking, you’ll need 6 x 4’ lengths and 6 x 2’ lengths, plus 4-6 x 4’ lengths (depending on the width of the decking used) for the base*

• Medium planter: 6’ x 2’ (approx. W1829 x D610mm)
  - Fits roughly 18 to 24 plants
  - Using W50 x T47mm timber sticks, you’ll need 8 x 6’ lengths and 8 x 2’ lengths, plus 4 x 6’ lengths of 150mm wide gravel board for the base*
  - Using decking, you’ll need 6 x 6’ lengths and 6 x 2’ lengths, plus 4-6 x 6’ lengths (depending on the width of the decking used) for the base*

• Large planter: 8’ x 2’ (approx. W2438 x 610mm)
  - Fits roughly 24 to 32 plants
  - Using W50 x T47mm timber sticks, you’ll need 8 x 8’ lengths and 8 x 2’ lengths, plus 4 x 8’ lengths of 150mm wide gravel board for the base*
  - Using decking, you’ll need 6 x 8’ lengths and 6 x 2’ lengths, plus 4-6 x 8’ lengths (depending on the width of the decking used) for the base*

* You’ll only need a base if the planter will sit on paving or decking, not soil. Don’t cut the base wood until the side frame has been created, as the exact size will be slightly larger than quoted.

Step 3: Cut your wood to size

Measure and cut your first long length using a mitre or hand saw. Try to cut the ends as squarely as possible so you get a smooth finish on your planter. Use this piece as a template to cut all pieces of the same length. Then do the same for the shorter lengths and the baseboards. 

Top tip: If you buy your wood in B&Q, we can cut it for you in-store (restrictions apply, check your nearest store for details)..  

Step 4: Assemble your wooden planter

Using timber sticks:

• Drill a pilot hole in each length for the screws, about 2.5mm from the end.

• Lay out two long and two short lengths, butting the edges together to form a frame. Use a set square to ensure the joints are square, then attach the pieces with 7.5mm screws.

• Cut the gravel board to the appropriate lengths to cover the base of the frame, then attach it with screws.

• Turn the frame over and attach another layer of stick timber over the first, building it up to 4 layers.

• Line the planter with plastic, attaching it with a staple gun.

Using decking:

• Assemble the sides of the first layer of the frame, butting the small pieces of wood up to the long pieces. Use a set square to ensure the joints are square, then attach the pieces using two self-tapping decking screws, screwed into the short pieces ¾ of an inch from the top and bottom.

• Cut the base pieces to the appropriate lengths to cover the base of the frame, then attach them with screws.

• Turn the frame over and attach another layer of decking slats over the first, building it up to 3 layers.

• Line the planter with plastic, attaching it with a staple gun.

Top tip: Use stainless steel screws: they won’t go rusty outdoors.

Step 5: Create your drainage holes

Making drainage holes is a vital step that shouldn’t be missed. Without holes, the soil can become waterlogged and kill plant roots.

As a rough guide, you’ll need the following:

• Small planter: 4 x ¼ inch holes
• Medium planter: 6 x ½ inch holes
• Large planter: 8 x 1-inch holes

Space the holes evenly, and don’t drill them too close to the edges.

Step 6: Finishing

Sanding isn’t vital, but it gives your planter a nice finish and will prevent splinters. Use an orbital sander, oscillating multi-tool , or coarse sandpaper.

Timber stick planters can be painted with wood stain or fence paint. Both protect the wood from the elements, but stain soaks into the wood to provide the best protection, whereas paint sits on the surface.

Step 7: Preparing your planter

Add a layer of gravel, broken pots, or large stones to the planter's base for drainage. Then fill it with soil or compost suitable for the type of plants or vegetables you want to grow.

Now it’s ready for planting!

Safety first!

As with any DIY project, don’t forget to take safety precautions. For example, wear gloves and safety goggles to protect yourself from splinters and flying debris when cutting wood.

FAQs