Making a Concrete Planter

The project here provides you with the opportunity to combine aspects of two previous projects (building garden walls, and building a raised pond) to create raised planters. These low, double-skin walls, which in this example terminate in hollow piers, are filled with soil and can be planted with your favourite specimens. They can be straight or curving ‘serpents’ through your garden and the piers can be square, rectangular or – if you are feeling particularly inspired – even circular, as it is possible to buy decorative bricks or blocks cast into curved forms.

The low walls of concrete planters will be softened in time as the plants grow and spill over the edges. You could incorporate some decorative metalwork – an obelisk perhaps to add additional height – or even some attractive outdoor lights in the pier ends. As always, the walls will only be as good as their foundations, so careful planning, excavation and preparation are vital to ensure good, strong walls.

Finally, don’t forget that as with all ‘containers’ the plants growing in them will be reliant on you for their food and water, and could easily dry out in summer.

Step-by-Step Instructions

1 ‘Double wall’ construction

The planters are made by building two parallel walls of the same height with a gap between them. If you want a wide gap, say about 600mm (2ft) wide, keep the walls quite low.Taller walls should have a proportionally smaller gap so they remain strong and upright.

2 Adding coping stones

When you have reached the desired wall height, finish the walls with coping stones bedded into mortar tar. Work out the proportions of the piers according to the materials: note here that, rather than having to cut a coping stone to size, the supporting walls have been built to accommodate them with ease.

3 Checking levels

Gently tap the coping into the mortar bed using the handle of a club hammer or mallet and use a spirit level to check it is horizontal. Check the levels all the way around the piers and across them diagonally.

4 The finished planters

The finished planters, filled with soil, are ready for planting up. You can part fill the spaces with rubble to provide good drainage – this also cuts down on the amount of soil or compost you’ll need.

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