Chalky soils: plants for

Chalky soils are alkaline and free-draining, and the depth of soil over chalk varies considerably. The key to gardening in these often drought-prone and nutrient poor soils is to select from the wide range of colourful plants that thrive in dry summers, need sharp drainage and moderate to low fertility.Limestone soils have similar characteristics.  

Chalky soils: plants for

Chalky soils: plants for

Quick facts

Top 5 plants for chalk:
Ceanothus
Campanula
Clematis
Dianthus
Geranium
Lavandula

Introduction

Many chalky soils are shallow, very free-draining and low in fertility, but variations exist. Where there is clay present, nutrient levels may be higher and the water holding capacity greater.

Where chalky soils are deep, they can be moisture-retentive and support a wide range of plants. They will not support ericaceous plants such as camellia and rhododendrons that need acid soil conditions. Very chalky soils may contain lumps of visible chalky white stone. Such soils cannot be acidified, and it is better to choose plants that will thrive in alkaline conditions.

When planting on chalky soils it is important to first establish how deep the topsoil is. Many trees and shrubs that will tolerate alkaline soil conditions may become chlorotic (yellow) on shallow soils over chalks. In some gardens the soil layer may be very thin indeed – only a few inches – before hitting solid chalk. Where this is the case, topsoil will need to be brought in to make planting possible. On shallow soils over chalk where increasing soil depth is not an option, wildflower mixes selected for chalk tolerance may still thrive.

Practical considerations

When planting on chalky soils;

  • Break up the chalk to a depth of 75cm (30in) so that plant roots can spread out and establish
  • Whether bringing in new soil or improving existing soil, add plenty of well-rotted organic matter such as garden compost, composted green waste or farmyard manure
  • Smaller plants get established more quickly than more mature specimens
  • Mulch plants with organic matter to conserve moisture
  • Attention to watering will be required for a longer period than with other soil types as plants on chalky soils may take several seasons to establish and are more prone to drying

Suitable plants

(+)   Best grown on deep and moisture retentive soils over chalk
(gc) Ground cover plants
(v)   variegated foliage
(e)   evergreen foliage
AGM - The RHS Award of Garden Merit

Many popular species and cultivars are listed below If you would prefer to view a full list of suitable plants for chalky and alkaline soils, try the RHS Find a Plant.

Trees

Acer campestre, A. negundo, A. platanoides, A. pseudoplatanus
Aesculus × carnea, A. hippocastanum
(horse chestnut), A. indica
Arbutus unedo
(+) (e)
Carpinus betulus (common hornbeam)
Ceanothus arboreus 'Trewithen Blue' AGM (e)
Cercis siliquastrum
Corylus avellana cultivars, C. avellana 'Contorta' AGM, C. colurna AGM, C. maxima cultivars
Crataegus laevigata (hawthorn)
Euonymus europaeus (spindle)
Fagus sylvatica (common beech)
Fraxinus excelsior, F. ornus (ash)
Ligustrum lucidum AGM (e)
Malus (apple, crab apple)
Morus nigra (black mulberry)
Prunus
(flowering cherries)
Pyrus (common pear and ornamental) (+)
Quercus robur (common oak)
Sorbus aria (whitebeam), S. intermedia

Conifers

Cedrus including C. atlantica (Atlas cedar), C. deodara AGM (Deodar cedar), C. libani AGM (Cedar of Lebanon) (e)
Chamaecyparis (+) (e)
Ginkgo biloba (+)
Juniperus communis and J. × pfitzeriana (e)
Larix decidua, L. kaempferi (+)
Pinus mugo and P. nigra (e)
Taxus baccata (yew) (e) 
Thuja occidentalis (White cedar) , T. plicata (Western red cedar) (e)
Thujopsis dolobrata (e)

Shrubs

Aucuba japonica (e)
Berberis
Brachyglottis Dunedin Group 'Drysdale', B. Dunedin Group 'Sunshine' AGM, B. monroi,
B
Walberton's Silver Dormouse = 'Walbrach' AGM (e)
Buddleja davidii cultivars, B. fallowiana var. alba AGM, B. globosa AGM, B. lindleyana, B. × weyeriana
Buxus microphylla, B. sempervirens 'Latifolia Maculata' AGM (v), B. sempervirens 'Suffruticosa' (e)
Caragana arborescens
Ceanothus including C. 'Autumnal Blue' AGM, C. 'Dark Star' AGM, C. 'Concha' AGM,
C.
'Pershore Zanzibar' (v), C. 'Puget Blue' AGM, C. thrysiflorus var. repens AGM (e)
Ceratostigma including C. willmottianum Forest Blue = 'Lice' AGM, C. plumbagnoides (gc)
Cistus including C. × argenteus 'Peggy Sammons', C. creticus, C. × dansereaui 'Decumbens' AGM,
C. laurifolius, C. monspeliensis, C. × pulverulentus '
Sunset' AGM, C. × purpureus (e)
Choisya × dewitteana 'Aztec Pearl' AGM, C. ternata AGM, C. ternata Sundance = 'Lich' AGM
Collutea arborescens
Cytisus
Cornus mas
Cotoneaster
Deutzia
Dipelta floribunda
AGM, D. ventricosa
Elaeagnus angustifolia, E. commutata, E.
'Quicksilver'
Euonymus fortunei cultivars (gc), E. japonicus cultivars (e)
Forsythia 'Fiesta' (v), F. × intermedia 'Lynwood Variety' AGM, F. suspensa
Fuchsia
Genista cinerea, G. lydia
× Halimiocistus sahucii
AGM (gc), × H. wintonensis 'Merrist Wood Cream' AGM (e)
Halimium calycinum, H. lasianthum, H. 'Susan' AGM (e)
Hebe (e)
Hibiscus syriacus, H. sinosyriacus
Hypericum
Laurus nobilis
(+) (e)
Lavandula (e)
Ligustrum japoniucm, L. ovalifolium, L. quihoui (e)
Lonicera nitida, L. pileata (e)
Mahonia aquifolium, M. × media (+) (e)
Olearia (e)
Paeonia delavayi, P. suffruticosa
Potentilla fruticosa

Pyracantha including P. coccinea 'Red Column', P. 'Orange Glow' AGM, P. 'Teton' AGM (e)
Rhus glabra, R. × pulvinata (Autumn Lace Group) 'Red Autumn Lace' AGM (+)
Ribes laurifolium, R. odoratum, R. sanguineum, R.speciosum
Romneya coulteri
AGM
Rosmarinus officinalis (e)
Rubus biflorus AGM, R.cockburnianus 'Goldenvale' AGM, R. lineatus, R. spectabilis 'Olympic Double',
R. thibetanus
'Silver Fern'
Sambucus nigra, S. racemosa
Santolina chamaecyparissus, S. pinnata
subsp.neapolitana AGM. S. rosmarinifolia (e)
Sarcococca confusa AGM, S. hookeriana var. digyna, S. ruscifolia var. chinensis 'Dragon's Gate' AGM (e)
Spartium junceum
Spiraea 'Arguta' AGM, S.japonica 'Anthony Waterer' (v), S. japonica 'Goldflame',
S. japonica
Magic Carpet = 'Walbuma' AGM (v), S. nipponica 'Snowmound' AGM
Syringa (lilac)
Tamarix parviflora AGM, T. ramosissima 'Pink Cascade' AGM, T. tetrandra AGM
Teucrium fruticans, T. × lucidrys (e)
Viburnum (most)
Vinca difformis, V. major, V. minor (gc) (e)
Weigela florida, W. middendorfiana, W. praecox
Yucca filamentosa, Y. flaccida
(e)

Climbers and wall shrubs

Actinidia kolomikta AGM, A.deliciosa (Kiwi fruit)
Akebia × pentaphylla, A. quinata, A. trifoliata
Clematis
Cotoneaster atropurpureus 'Variegatus' AGM, C. horizontalis
Fremontodendron
'California Glory' AGM (e)
Hedera (ivy) (e)
Jasminum beesianum, J. nudiflorum AGM, J. officinale cultivars (jasmine)
Lonicera periclymenum (honeysuckle) (+)
Parthenocissus henryana (Chinese Virginia creeper), P. quinquifolia (Virginia creeper),
P. tricuspidata (Boston ivy)
Passiflora caerulea AGM
Solanum crispum 'Glasnevin' AGM, S. dulcamara, S. laxum 'Album' AGM
Trachelospermum asiaticum AGM, T. jasminoides AGM (e)
Vitis (ornamental vines)

Herbaceous perennials

Acanthus mollis, A. spinosus
Achillea
Actaea simplex
Atropurpurea Group 'Brunette' AGM
Adenophora bulleyana
Agapanthus
Agastache
Alstroemeria
Anchusa azurea 
'Lodden Royalist'
Anemone hupehensis, A. × hybrida
Anthemis punctata
subsp. cupaniana AGM, A. tinctoria 'E.C. 'Buxton', A. tinctoria 'Sauce Hollandaise'
Aquilegia
Armeria
Artemisia absinthium 'Lambrook Silver', A. arborescens AGM, A. lactiflora Guizhou Group
Aster  
Astilbe
Ballota pseudodictamnus AGM (e)
Bergenia 'Bressingham Ruby', B. cilliata, B. 'Morgenrote' AGM, B. 'Overture' (e)
Calendula officinalis (Pot marigold)
Campanula glomerata 'Superba' AGM, C. 'Kent Belle' AGM, C. lactiflora 'Pritchards Variety' AGM
Catanache caerulea 'Major' AGM
Centaurea
Centranthus ruber
Cerinthe major
'Purpurascens'
Chelone obliqua
Convallaria majalis
(gc)
Coreopsis
Corydalis
Crambe cordifolia
AGM
Crocosmia
Cynara cardunculus AGM (cardoon), C. cardunculus  Scolymus Group (artichoke)


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