I am fortunate to have a boundary wall that has two skins of stone filled with soil. This makes an habitat for plants that I can use to grow something a bit different.

The Pros & Cons of a Filled Wall.

The wall raises the working height and brings plants nearer to eye level.

The soil is of poor quality as goodness is leached away. This suits some alpines and nasturtiums.

Due to holes somewhere the soil washes out in some spots and I am always looking to refill or stop the leak.

The wall is dry and gets hot in the sun although the stone provides some cooler protection for roots.

Slugs do not like to climb the wall (just send gardeners up it)

Suitable Plant Types for Walls

• Dry condition lovers and sun seekers like Thyme
• Plants that like a baking like Pulsatilla
• Plants that hold there own water store like Sedums and Houseleeks.
• Alpines and similar plants with long roots.
• Trailing plants and poor soil plants.

Some Plants recommended by Cambridge University Gardening services site
Crassula sarcocaulis
Helichrysum ‘Sulphur Light’
Sedum acre
Sempervivum ciliosum
Saxifraga species
Euryops acraeus
Artemisia schmidtiana nana
Helianthemum varieties
Ajuga reptans
Aribis alpina
Dianthus deltoides
Geranium dalmaticum
Erigeron ‘Profusion’
Lewisia cotyledon
Lobelia cultivars
Portulaca grandiflora
Vinca minor
Phlox douglasii
Hypericum olympicum
Alyssum montanum