Plants for Clay Soils

Clay soil is unusually wet, glutinous and heavy in winter, and during drier summers sometimes shrinks and cracks, damaging plant roots.
Whether establishing a new garden on clay or renovating an older one, always choose plants that will tolerate and grow satisfactorily in clay soil.  Prepare the soil thoroughly, digging in the autumn, then leaving roughly dug over winter to benefit from the weathering effects of frost and winter rains.  Dig in organic matter, and work in grit or sharp sand to ensure the soil is well-drained.  Plant in early spring at the beginning of the growing season, to avoid losses over winter.


Alnus  glutinosa (Black Alder / Common Alder)
Slow-growing, deciduous, conical tree.

H to 25m (80)ft, S 10m (30ft). Bright yellow leaves until mid-summer later becoming pale green. Yellow-brown catkins are borne in spring.

Fraxinus (Ash)
Genus of deciduous trees and shrubs, grown mainly for their foliage of paired leaflets;  flowers are usually insignificant.

Juglans nigra (Black Walnut)
Fast growing, deciduous, handsome, spreading tree with large aromatic leaves of many dark-green leaflets. Produces edible nuts in autumn. H to 30m (100ft), S 22.5m (75ft)

Populus (Poplar)
Genus of deciduous trees, grown for their  habit, foliage, and very quick growth.  Has catkins in late-winter or spring.  Female trees produce copious amounts of fluffy, white seeds.

Quercus palustris (Pin Oak)
Fast-growing, deciduous, spreading tree with slender branches, pendulous at the tips.  Deeply lobed, glossy, bright green leaves turn scarlet or red in autumn. H 20m (70ft),  S 10m (30ft).

Quercus robur (Common Oak)
Deciduous, spreading, rugged tree. Bears oblong, wavy, lobed, dark-green leaves.        H and S 25m (80ft)

Salix babylonica ‘Tortuosa’ (Dragon’s-claw willow)
Fast-growing, deciduous, spreading tree with curiously twisted shoots and contorted narrow, tapering, bright green leaves. H 15m (50ft), S 10m (30ft)


Onoclea sensibilis (Sensitive fern)
Deciduous, creeping fern with handsome, arching, divided, fresh pale green fronds, often suffused pinkish-brown in spring. In autumn fronds turn yellowish-brown.           H and S 45cm (18”)

Osmunda regalis (Royal fern)
Deciduous fern with elegant, broadly oval to oblong, divided, bright green fronds, pinkish when young. Mature plants bear tassel-like, rust-brown fertile flower spikes at ends of taller fronds. H2m (6ft), S 1m (3ft).


Polystichum setiferum groups (Soft Shield fern)

Woodwardia radicans (Chain fern)
Vigorous, evergreen, spreading fern. Large, broadly lance-shaped, coarsely divided,  mid-green, arching fronds.


Calycanthus floridus (Carolina allspice)
Deciduous, bushy shrub with aromatic dark green leaves and, from early to mid-summer, fragrant, red flowers with masses of spreading petals. H and S 2m (6ft)

Cornus alba ‘Sibirica’ (Red Stemmed Dogwood)
Deciduous, up-right shrub with scarlet young shoots in winter. Has dark green foliage and heads of creamy-white flowers in late-spring and summer. H and S 2m (6ft)

Kalmia latifolia  (Calico bush)
Evergreen, bushy, dense shrub. In early summer large clusters of pink flowers open from distinctly crimped buds amid glossy, rich green foliage. H and S 3m (10ft)

Magnolia virginiana. (Sweet Bay)
Deciduous or semi-evergreen, conical shrub or tree. Very fragrant, cup-shaped, creamy-white flowers fro early summer to early autumn. Glossy, mid to dark-green leaves which are bluish-white beneath. H 9m (28ft) S 6m (20ft)

Salix purpurea (Purple osier)
Deciduous, bushy, spreading shrub. Grey male catkins and insignificant female catkins are borne on slender, often purple, shoots in spring.H and S 5m (15ft)

Sambucus racemosa (Red Berried Elder)
Deciduous, bushy shrub.  Star-shaped, creamy-yellow flowers, borne in dense, conical clusters in mid-spring are succeeded by spherical, red fruits. H and S 3m (10ft)


Celastrus scandens (American Bittersweet, Staff tree)
Deciduous, twining climber. Tiny greenish flowers are borne in small clusters in summer. Long lasting, spherical fruits are produced in long bunches. Each fruit splits to show an orange interior and scarlet seeds.   H to 10m (30ft)

Humulus lupinus ‘aureus’ (Golden Hop)
Herbaceous, twining climber with, rough, hairy stems and toothed, yellowish leaves divided into 3 or 5 lobes. Greenish, female flower spikes are borne in pendant clusters in autumn H to 6m (20ft)

Vitis coignetiae (Crimson Glory Vine)
Vigorous, deciduous, tendril climber. Large leaves, brown haired beneath, are brightly coloured in autumn. Tiny, pale green flowers in summer, followed by purplish-bloomed, black berries. H to 15m (50ft)


Aruncus dioicus (Goat’s beard)
Hummock-forming perennial carrying large leaves with lance shaped leaflets on tall stems and above them, in mid-summer, branching plumes of tiny, creamy-white flowers.                 H 2m (6ft), S 1.2m (4ft)

Darmera pelata (Umbrella Plant)
Spreading perennial with large, rounded leaves.  Has clusters of white or pale-pink flowers in spring on white haired stems before foliage appears. H 1-1,2m (3-4ft), S 60cm (2ft)

Gunnera manicata
Architectural perennial with rounded, prickly-edged leaves, to 1.5m (5ft) across.  Has conical, light green flower spikes in mid-summer, followed by orange-brown seed pods.                 H 2m (6ft), S 2.2m (7ft)

Houttuynia cordata ‘Chameleon’ 
Vigorous deciduous perennial. Aromatic, leathery leaves are splashed yellow and red. Has small sprays of white flowers in summer.   H 10cm (4”) S indefinite.

Iris laevigata (Japanese)
Rhizomatous, beardless, japanese iris.  Sparsely branched stem produces 2-4 blue, blue-purple or white flowers through summer. H 60-90cm (2-3ft) S indefinite.

Lythrum (purple loosestrife)
Genus of summer flowering perennials. Grow in full sun or semi-shade.

Primula florindae (Giant cowslip)
Bold, rosette-forming perennial.  In summer large heads of pendant, bell-shaped, sulphur-yellow flowers appear above broadly lance-shaped, toothed, mid-green leaves. H 1.2m (4ft) S 1m (3ft)

Primula japonica
Robust, rosette-forming, candelabra primula. Early summer produces deep-red flowers on stout stems above oval to lance-shaped, toothed, coarse, pale green leaves.                      H and S 45cm (18”)

Trollius (Globeflower)
Genus of spring or summer flowering perennials.  Tolerates sun or shade. H from 60cm (2ft) S from 30cm (1ft)