Although relatively expensive to build, brick or stone walls provide excellent boundaries for gardens and offer considerable possibilities for 'vertical' gardening. The height and aspect of a wall usually determines what may be grown against it - for example, plants that thrive on south-facing aspects will not fare well on a north facing wall.

When choosing climbers to grow up walls, make sure that the colour of the foliage or flowers harmonises well with that of the walls. Pale or grey walls show off pinks, reds, yellows and blues well, whilst yellow or red walls accentuate dark reds, greens, purples, blues and whites.

Silver-or golden-variegated forms of ivy (Hedera) can lighten up gloomy or dark walls and are ideal for such sites. However, whilst they should not damage walls in good condition, they are not recommended for walls in poor repair as their aerial roots frequently loosen the mortar.

Even without plants, some walls, especially old, mellow ones, make attractive backgrounds and it may be desirable to leave them partially uncovered.

If you're interested in building your own wall, take a look at our walling section in garden features.