Choosing Plants for a Walled Garden

Walled gardens are among the most evocative features of Britain's historic landscapes. From the great kitchen gardens of country houses to the sheltered courtyards of old rectories and castles, these enclosed spaces were designed to cheat the climate. The walls block cold winds, trap warmth, and create a series of distinct microclimates. Choosing plants for such a garden is a pleasure, but it rewards careful observation. Aspect and soil still dictate what will thrive.

The Microclimate Created by Old Walls

A south-facing wall is the prize. Brick or stone absorbs heat during the day and releases it slowly after sunset, raising night temperatures by several degrees. This thermal mass extends the growing season and protects tender blossoms from late frosts. An east-facing wall catches morning sun, which can be a mixed blessing: rapid thawing of frosted buds may damage them more than a slow thaw. West-facing walls are warm but exposed to prevailing winds and driving rain. North-facing walls remain cool and often damp, suiting woodland plants and late-fruiting cherries.

Watch for frost pockets at the lowest point of the garden, where cold air collects. Also note the rain shadow: the soil at the base of a wall can be surprisingly dry, even after heavy rain, because the wall intercepts much of the moisture.

Reading the Soil Beneath the Beds

Historic walled gardens often have deep, fertile soil, improved over centuries with manure and compost. But do not assume this. Lime mortar from brick or stone walls can raise the pH, making the soil alkaline. Test before planting. Acid-loving plants such as camellias and rhododendrons will struggle unless you use containers or add ericaceous compost.

Drainage varies enormously. Heavy clay holds water and can waterlog roots in winter; light sandy soil dries out quickly in summer. Both can be improved with organic matter. Plant shrubs and climbers at least 30–45 cm from the wall to avoid the driest zone and to allow air circulation. A mulch of well-rotted manure or leaf mould each spring will conserve moisture and suppress weeds.

Fruit Trees for Warm Walls

The classic use of a south or west wall is for trained fruit. Fan-trained peaches, nectarines and apricots ripened reliably against British brick long before garden centres stocked exotic varieties. Figs also love a warm wall, though restrict their roots to encourage fruiting. Grapes can be grown under glass or against a sheltered wall in milder counties.

• Peaches and nectarines: fan-train on a south wall; hand-pollinate if insects are scarce.
• Apricots: early-flowering, so choose a frost-free spot; 'Moorpark' is a historic favourite.
• Figs: 'Brown Turkey' is reliable; plant in a large pot or root-restricting membrane.
• Apples and pears: cordons or espaliers suit east and west walls; choose self-fertile or partner varieties.
• Morello cherry: happy on a north wall, cropping well in shade.

Roses and Climbing Plants

Roses adore walled gardens. The shelter allows tender tea roses and noisette roses to flourish, their loose, fragrant blooms lasting longer without wind damage. Climbing roses such as 'Gloire de Dijon' or 'Madame Alfred Carrière' can be trained along wires. Plant them 45 cm from the wall, leaning the stems towards the support, and tie in regularly.

Interplant with clematis for extended interest. Early-flowering clematis like Clematis alpina need little pruning, whilst late-flowering types such as Clematis viticella can be cut back hard in spring. Jasmine and passionflower also relish the warmth, though they may need winter protection in colder areas.

Tender Shrubs and Exotics

Sheltered walls allow a touch of the exotic. Camellias, magnolias and ceanothus all benefit from protection from cold winds. Olives, myrtles and pittosporum can survive outdoors in mild regions, especially against a south wall. In colder gardens, grow citrus in pots and move them under cover for winter.

Agapanthus and hedychium (ginger lily) add architectural foliage and late-summer flowers. Protect their crowns with a thick mulch of bracken or straw. Even in a walled garden, be ready to wrap tender specimens in fleece during severe frosts.

Shady and North-Facing Walls

Not every wall needs to be warm. North-facing walls offer cool, moist conditions ideal for ferns, hostas and epimedium. Spring bulbs such as snowdrops and cyclamen coum will naturalise in the leaf litter. Rhubarb thrives in partial shade, and cooking apples or morello cherries crop well on a north wall.

Distinguish between damp shade and dry shade. Damp shade suits ferns and astilbes; dry shade under a wall calls for tough plants like epimedium, hardy geraniums and wood anemones. Improve the soil with leaf mould before planting.