Introduction

When planting on heavy clay soil it is always advisable to attempt some improvement of the soil, by working in organic matter. Mulching the surface of the soil will also help improve the texture.

• One of these materials is long manure (manure that still has a proportion of visible straw remaining) or composted bark
• Finer grades of composted bark, leafmould, leaf litter, garden compost or mushroom compost will still have a beneficial effect, but to a lesser extent
• Dig coarse grit into the soil profile is often recommended, but the quantity required to have a beneficial effect makes this an impractical solution on all but the smallest scale
• When planting on clay soils, the bottom of the planting hole should be broken up before planting and the sides of the hole broken down using a garden fork. If not loosened, a sump may be formed in that water can collect, resulting in probable plant death from waterlogging
• It is a good idea to delay planting on heavy clay soils until late winter or early spring, when there is less time for dormant roots to become waterlogged and cold
• Mulch the base of the plants in spring with a 7.5cm (3in) layer of well-rotted organic matter which will help to retain moisture and suppress weed growth. Leave a gap of 7.5cm (3in) between the stems and the mulch to decrease the chance of rots developing at the base. Continually maintaining this mulch will gradually improve the soil profile
• Freezing and thawing over winter of ground dug in October aids soil breakdown and helps to form spring seedbeds

Suitable plants

Trees

Acer japonicum, A. palmatum (Japanese maple)
Amelanchier lamarckii AGM
Betula (birch)
Crataegus (hawthorn)
Eucalyptus
Laburnum anagyroides, L. × watereri 'Vossii' AGM
Liquidambar styraciflua
Malus (crab apple)
Pyrus salicifolia 'Pendula' AGM (weeping pear)
Sorbus

Conifers

Abies koreana
Araucaria araucana
Chamaecyparis lawsoniana, C. obtusa, C. pisifera
Ginkgo biloba AGM
Juniperus chinensis, J. × pfitzeriana
Picea abies, P. glauca, P. omorika AGM, P. orientalis AGM, P. pungens
Pseudotsuga menziesii
Taxodium distichum AGM
Thuja plicata
Tsuga candensis, T. heterophylla AGM

Shrubs

Berberis (evergreen and deciduous)
Buddleja
Cotoneaster (evergreen and deciduous)
Escallonia (evergreen)
Fuchsia
Hydrangea
Mahonia
Rosa
Spiraea
Viburnum (deciduous and evergreen)
Weigela

Ground-covering plants

Bergenia
Euonymus fortunei
Gaultheria procumbens AGM, G. shallon, G. × wisleyensis 'Wisley Pearl'
Geranium
Hypericum calycinum
Juniperus communis, J. rigida subsp. conferta 'Blue Pacific', J. horizontalis 'Wilsonii' 
Lamium galeobdolon
Persicaria affinis, P. bistorta, P. vacciniifolia AGM
Vinca major, V. minor

Climbers and wall shrubs

Chaenomeles speciosa 'Moerloosei' AGM (pink) and 'Nivalis' (white)
Cotoneaster horizontalis AGM, C. lacteus AGM
Forsythia suspensa AGM
Escallonia 'C.F. Ball', E. 'Edinensis' AGM
Garrya elliptica 'James Roof' AGM
Hydrangea anomala subsp. petiolaris
Kerria japonica
Lonicera japonica, L. periclymenum
Pyracantha
Rosa

Herbaceous perennials

Alchemilla mollis
Anemone hupehensis var. japonica, A. × hybrida
Aster novae-angliae, A. novi-belgii
Astrantia
Geranium
Helleborus
Hosta
Kniphofia
Sedum spectabile AGM
Solidago

Links

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