When planting on heavy clay soil it is always advisable to attempt some improvement of the soil, by working in organic matter.

Mulch is a layer of material, at least 5cm (2in) thick, applied to the soil surface in late autumn to late winter (Nov-Feb). It is used to provide frost protection, improve plant growth by adding nutrients or increasing organic matter content, reducing water loss from the soil, for decorative purposes and suppressing weeds. Examples include well-rotted garden compost and manure, chipped bark, gravel, grit and slate chippings.

• 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
  Can refer to either home-made garden compost or seed/potting compost: • Garden compost is a soil improver made from decomposed plant waste, usually in a compost bin or heap. It is added to soil to improve its fertility, structure and water-holding capacity. Seed or potting composts are used for growing seedlings or plants in containers - a wide range of commercially produced peat-free composts are available, made from a mix of various ingredients, such as loam, composted bark, coir and sand, although you can mix your own.

  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
  Dormancy refers to a period of inactivity in plants, during which they slow down or stop their growth, conserving energy and resources. This is a natural process that helps them survive harsh conditions, such as winter or drought. Dormancy in seeds is a mechanism that prevents them germinating until environmental conditions are favourable for growth.

  dormant roots to become
  Describes soil or potting compost that is saturated with water. The water displaces air from the spaces between soil particles and plant roots can literally drown, unless they are adapted to growing in waterlogged conditions. Waterlogging is common on poorly drained soil or when heavy soil is compacted. 

  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 is a layer of material, at least 5cm (2in) thick, applied to the soil surface in late autumn to late winter (Nov-Feb). It is used to provide frost protection, improve plant growth by adding nutrients or increasing organic matter content, reducing water loss from the soil, for decorative purposes and suppressing weeds. Examples include well-rotted garden compost and manure, chipped bark, gravel, grit and slate chippings.

  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

Trees

Acer japonicum 'Aconitifolium' AGM A. palmatum 'Inabashidare' AGM (Japanese maple)
Aesculus parviflora AGM
Amelanchier 'RJ Hilton' AGM
Betula utilis subsp. jacquemontii 'Silver Shadow' AGM (birch)
Crataegus laevigata 'Crimson Cloud' AGM, C. persimilis prunifolia AGM (hawthorn)
Eucalyptus gunnii 'France Bleu' ('Rengun')^PBR), Eucalyptus pauciflora subsp niphophila AGM
Ilex aquifolium 'Argentea Variegata' AGM
Laburnum × watereri 'Vossii' AGM
Liquidambar styriciflua Worplesdon' AGM
Malus atrosanguinea 'Gorgeous' AGM, Malus 'Evereste' AGM(crab apple)
Prunus 'Shirotae' AGM
Pyrus salicifolia 'Pendula' AGM (weeping pear)
Sorbus 'Olympic Flame' AGM, Sorbus pseudohupehensis AGM

Conifers

Abies koreana 'Horstmann's Silberlocke' AGM
Chamaecyparis lawsoniana 'Ellwoods Gold' AGM, C. obtusa 'Nana Gracilis' AGM, C. pisifera 'Boulevard' AGM
Ginkgo biloba 'Saratoga' (m) AGM
Juniperus chinensis 'Pyramidalis' AGM, J.×pfitzeriana 'Old Gold' AGM
Picea abies 'Little Gem' AGM, P. glauca var. albertina 'Conica' AGM, P. omorika AGM, P. pungens (Glauca Group) 'Hoopsii' AGM
Taxodium distichum, Taxodium sempervirens AGM
Thuja plicata 'Atrovirens' AGM

Shrubs

Abelia ×  grandiflora 'Francis Mason' AGM
Berberis (evergreen and deciduous), Berberis x irwinii 'Corallina Compacta' AGM, Berberis thunbergii 'Admiration' AGM
Buddleja × weyeriana 'Bicolor', B. 'Royal Red' AGM, B. 'Black Knight' AGM
Calluna vulgaris 'Dark Star' AGM
Ceratostigma plumbaginoides AGM
Cotoneaster (evergreen and deciduous), Cotoneaster × watereri 'Cornubia' AGM, Cotoneaster dammeri 'Juliet' AGM
Escallonia (evergreen), Escallonia 'Iveyi' AGM, Escallonia 'Apple Blossom' AGM
Fuchsia magallanica 'Tricolor' AGM, F. Madame Cornélissen' AGM
Hibiscus syriacus 'Oiseau Bleu' AGM
Hydrangea macrophylla 'Blaumeise' (Teller Series) AGM
Mahonia × media 'Winter Sun' AGM
Osmanthus ×  burkwoodii AGM
Philadelphus 'Snowbelle', Philadelphus × lemoinei 'Belle Etoile' AGM
Potentilla fruticosa 'Bellissima'
Rosa
Sarcococca hookeriana var. digyna 'Purple Stem' AGM
Spiraea × bulmada 'Goldflame'
Viburnum (deciduous and evergreen), Viburnum plicatum f. tomentosum 'Kilimanjaro Sunrise' (Jww5PBR), V. × hillieri 'Winton' AGM
Weigela florida 'Wine and Roses' AGM, W. 'Red Prince' AGM

Ground-covering plants

Arisarum proboscideum
Bergenia 'Overture', B. 'Bressingham White' AGM
Erigeron karvinskianus AGM
Euonymus fortunei 'Wolong Ghost' AGM, E. 'Emerald Gaiety' AGM, 
Gaultheria procumbens AGM (acid soil)
Geranium 'Orion' AGM, G. × cantabrigiense 'Ingwersen' AGM
Hypericum calycinum
Juniperus communis 'Green Carpet' AGM, Juniperus horizontalis 'Golden Carpet' AGM
Lamium maculatum 'Beacon Silver'
Persicaria affinis 'Darjeeling Red' AGM, P. bistorta 'Superba' AGM P. vacciniifolia AGM Persicaria microcephela 'Purple Fantasy'
Vinca major 'Variegata' AGM Vinca minor 'Bowles's Variety' AGM

Climbers and wall shrubs

Campsis × tagliabuana 'Madame Galen' AGM
Chaenomeles speciosa 'Moerloosei' AGM (pink) and 'Nivalis' (white)
C. lacteus AGM
Forsythia suspensa 
Escallonia 'Crimson Spire AGM, E. 'Donard Radiance' AGM
Garrya elliptica 'James Roof' AGM
Hydrangea anomala subsp. petiolaris AGM
Kerria japonica 'Golden Guinea' AGM
Lonicera japonica 'Hall's Prolific' AGM, L. periclymenum 'Late Red'
Pyracantha 'Saphyr Orange' (Cadange) AGM
Rosa
Rosmarinus officinalis 'Foxtail' AGM
Salvia microphylla 'Cerro Potosi' AGM

Herbaceous perennials

Alchemilla mollis AGM, Alchemilla erythropoda AGM
Amsonia tabernaemontana var. salicifolia
Anemone hupehensis var.japonica 'Pamina' AGM, A × hybrida 'Andrea Atkinson'
Aster novae-angliae 'Helen Picton' AGM A. Novi-Belgii 'Coombe Fishacre' AGM
Astilbe 'Bronce Elegans' AGM
Astrantia 'Roma' AGM
Campanula lactiflora 'Prichard's Variety' AGM
Epimedium 'Spine Tingler' AGM
Euphorbia griffithii 'Fireglow'
Geranium 'Patricia' AGM
Helenium 'Sahin's Early Flowerer' AGM
Helleborus argutifolius AGM
Hosta 'Regal Splendour' AGM
Paeonia 'Coral Charm' AGM
Persicaria amplexicaulis 'Taurus'
Phlox paniculata 'Blue Paradise' AGM
Polemonium 'Northern Lights' AGM
Primula beesiana AGM
Rudbeckia 'Goldsturm' AGM
Salvia glutinosa
Solidago rugosa 'Fireworks' AGM
Spiraea venusta 'Magnifica' AGM
Thalictrum 'Black Stockings' AGM, Thalictrum flavum subsp. glaucum
Veronicastrum virginicum 'Lavendelturm' AGM

Ferns

Grasses

Calamagrostis × acutifolia 'Karl Foerster' AGM
Calamagrostis brachytricha
Carex elata 'Aurea' AGM, Carex oshimensis 'Evergold' AGM
Miscanthus sinensis 'Kleine Silberspinne' AGM
Panicum virgatum 'Dallas Blues' AGM
Molinia caerulea subsp.'Transparent' AGM

Bulbs

Links

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