How to Make a DIY Triangular Planter Box

By   | Last Updated :   December 6, 2021 | Filed In :   DIY & How To

Triangular planter boxes are very unusual and they’re an easy shape to construct. A triangle can be joined to any straight line in your garden environment such as the back of a bench or a wall.

You can decide the length and depth of your planter which can be positioned on the wall or ground. Triangular planter boxes often seem to be made of wood but there are plenty of ceramic, metal, and plastic versions available too.

Do you want to DIY your own triangular bench? Interior or exterior, this shape offers interest anywhere. Keep reading for ideas and plans!

Deluxe exterior triangular planter box

Who wouldn’t dream of lounging about on this double bench? With a triangular planter box attached to the back of the bench, imagine this filled with lavender in summer or wallflowers in spring.

triangular planter box

Image credit: @decustomtrades

You could make it in attractive wood with a visible grain. The planter would need lining in order to plant flowers.  What a fantastic place to relax with a cool drink after the backbreaking work of mowing the lawn!

Raised bed vegetable triangles

If the allotment is more your style, try triangular shapes for vegetable planters.

triangular raised bed

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Wall-mounted triangular planter boxes

Use these attractive triangle-shaped planters to brighten up any wall or building, like a shed. Their unusual shape is eye-catching and if you fill them with trailing flowers they will look fantastic in any season.

wall mounted triangular planter boxes

Image credit: Woodshed Ltd

Think clematis, nasturtiums, and busy Lizzies in summer. Primroses, cyclamen and pansies would look stunning in spring. Herbs are another alternative – parsley, basil, and chives will thrive in these planters provided they get some direct sunshine.

These triangular boxes come ready-made from treated wood, which makes them long-lasting as well as beautiful. They’re made of tanalised timber from responsibly sourced forests.

Other materials for your triangular planter boxes

Plastic is an ideal material for an indoor planter. A triangular shape makes it easy to position in a corner or you can use it as a centrepiece filled with flowers. It can also accommodate an easy-care, shade-tolerant plant, such as a spider or snake plant.

Glass. Although not strictly triangular, an exotic greenhouse or terrarium offers extra protection for delicate plants as well as being eye-catching and quirky in your home or garden.

concrete triangular planter boxes

Fill your home with quirky, triangular planters. These are made from concrete. Image credit: @livingart__official

DIY triangular beds

If you want to make your own large or small planter box, then the only limit is the space available and the material you use. If you have younger gardeners to help, make a recycled can planter box!

1. Tin can planter

You’ll need to collect 90-100 recycled cans. Most food cans have a 3 inch (7-8 cm) diameter so that’s 25 for each side plus a few extra to fill in any gaps.

  1. Wash them well and then stand them in the area where you want your planter bed.
  2. Measure the space available and then cut some cardboard as a guide to the pointed shape. Or make a string guide for the length of the planter and fix this in place with the string tied to sticks.
  3. Make one guide at 90 degrees as the right angle, then place 2 others at the other points of the shape. This is your outline and now you will add a row of cans to complete the triangular shape.
  4. Fill the cans with stones to keep them steady.
  5. Make the next line of tins and fill these too.
  6. Complete the triangular shape by adding more cans along the cardboard outline to suit your space.
  7. Once they are in place, create a lining by placing plastic or architectural fabric over the cardboard that’s already in place.
  8. All that is left is to think about drainage and then soil. Make some holes in the plastic. The cardboard will absorb lots of the water but may get waterlogged so make a few holes in this to allow excess water to drain away easily.

2. Brick planter

Bricks are another option. You will need some expertise to make the bed if you want to fix the bricks with cement. However, if you are happy to just lay them on top of each other and trust the soil to hold them in place, bricks can offer a rustic feel to any planter.

  1. Make a triangular shape in the same way as the tin can planter above, and position the bricks in the shape you want. There will be some issues at the corners and you will need to practise to get this correct! You can lay them at a right angle with one brick’s edge making the point of the triangle.
  2. If this all sounds like too much trouble, move on to the next option.
old brick triangular planter box

Stack old bricks to make an effective planter. Image credit: Pinterest

3. Large decorative dry stone planter

This is the easiest option of all 3. The stones will make a bumpy, textured edge to your triangular planter box, adding a natural finish and an excellent background for your plants to drape over. Farmers all over the world have found stones and slates when they were digging their land and used them to make a boundary for cattle or to define ownership of land. There are wonderful examples of dry stone walls worldwide. Go beachcombing or digging in the garden and wash the stones down well before placing them in shape.

stone planter

Hone your stone-walling skills and create an incredible planter. Image credit: Pinterest

Tina’s Tips

DIY corner planter box and plans

These links will give you some ideas on constructing your triangular planter box.


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