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

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 bullyana
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. 'Mogenrote' 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 oblique
Convalaria majalis
(gc)
Coreopsis
Corydalis
Crambe cordifolia
AGM
Crocosmia
Cynara cardunculus AGM (cardoon), C. cardunculus  Scolymus Group (artichoke)
Delphinium
Dianthus (most)
Dicentra 'Adrian Bloom', D. formosa 'Bacchanal' AGM
Digitalis purpurea
Doronicum 'Little Leo', D. orientale 'Magnificum'
Echinacea pallida, E. paradoxa, E. purpurea cultivars
Echinops bannaticus 'Blue Globe', E. ritro AGM (Globe thistle)
Eremurus × isabellinus, E. robustus AGM cultivars (foxtail lily)
Erigeron
Erodium pelargoniiflorum
Eryngium bourgatii
'Oxford Blue' AGM, E. giganteum 'Silver Ghost' AGM, E. × oliverianum AGM,
E. planum
cultivars
Eryisymum 'Bowles's Mauve' AGM (e)
Euphorbia amygdaloides 'Craigieburn', E. characias cultivars, E. dulcis 'Chameleon', E. mellifera AGM
Gaillardia × grandiflora 'Burgunder'
Galega officinalis
Gaura lindheimeri AGM
Geranium including G. 'Ann Folkard' AGM, G. clarkei 'Kashmir White', G. endressi AGM,
G. himalayense '
Gravetye', G. 'Johnsons Blue', G. 'Mavis Simpson' AGM, G. nodosum,
G. phaeum
'Lily Lovell', G. psilostemon AGM, G. renardii AGM, G. Rozanne = 'Gerwat' AGM
Geum rivale 'Leonards Variety', G. 'Totally Tangerine'
Gypsophila paniculata
Helenium
'Bressingham Gold', H. 'Butterpat' AGM, H. 'Moerheim Beauty' AGM
Helianthemum 'Fire Dragon' AGM, H. 'The Bride' AGM
Helleborus × argutifolius AGM, H. ericsmithii 'Winter Moonbeam', H. × hybridus cultivars, H. niger cultivars,
H. (Rodney Davey Marbled Group) 'Anna's Red', H. Walburton's Rosemary' = 'Walhero'
Hemerocallis
Hosta
Inula hookeri, I magnifica
Iris
(bearded)
Knautia macedonica
Kniphofia
Lamprocapnos spectablis
Leucanthemum × superbum
'Aglaia', L. × superbum 'T.E. Killen' AGM, L. vulgare (ox-eye daisy)
Liatris spicata
Limonium platyphyllum
Linum perenne

Lychnis chalcedonica AGM, L. coronaria AGM
Macleaya × kewensis 'Flamingo' AGM, M. microcarpa 'Kelway's Coral Plume' AGM
Malva moschata, M. sylvestris
Morina longifolia
Nepeta × faassenii
AGM, (cat mint), N. racemosa AGM
Oenothera speciosa 'Siskiyou'
Origanum 'Kent Beauty' AGM, O. 'Herrenhausen' AGM
Paeonia 'Buckeye Belle', P. lactiflora 'Bowl of Beauty' AGM, P. 'Duchesse de Nemours' AGM
Papaver commutatum 'Ladybird' AGM, P. nudicaule 'Summer Breeze Orange' AGM, P. orientale
Penstemon
Pensham series, P. 'Port Wine' AGM, P. 'Stapleford Gem' AGM, P. 'Windsor Red'
Persicaria affinis 'Darjeeling Red' AGM, P. amplexicaulis, P. bistorta 'Superba' AGM
Phlomis russelliana AGM, P. tuberosa 'Amazone' AGM
Physostegia virginiana 'Summer Snow' AGM
Platycodon grandiflorus AGM
Polemonium caeruleum, P. carneum, P. 'Heavenly Blue'
Potentilla atrosanguinea, P. nepalensis 'Miss Willmott', P. 'William Rollisson' AGM
Rudbeckia fulgida var. deamii AGM, R. fulgida var. sullivantii 'Goldsturm' AGM
Salvia guarantica 'Blue Enigma' AGM, S. 'Indigo Spires', S. nemorosa cultivars, Ssuperba cultivars,
S. × sylvestris cultivars
Scabiosa atropurpurea 'Chile Black', S. 'Butterfly Blue', S. caucasica 'Clive Greaves' AGM
Sedum erythrostictum 'Frosty Morn' (v), S. 'Herbstfreude' AGM, S. 'Jose Aubergine', S. 'Matrona',
S. spectabile cultivars, S. telphium 'Strawberries and Cream'
Sidalcea 'Elsie Heugh' AGM, S. 'Party Girl', S. 'Rose Queen'
Silene dioica, S. fimbriata, S. schafta 'Shell Pink', S. uniflora 'Druett's Variegated' (v)
Solidago 'Cloth of Gold', S. rugosa 'Fireworks' AGM
Tanacetum (pyrethrum)
Thalictrum aquilegiifolium 'Thundercloud' AGM, T. delavayi AGM
Tiarella cordifolia AGM, T. 'Pink Skyrocket, T. 'Spring Symphony'
Tradescantia Andersoniana Group 'Bilberry Ice', T. Andersoniana Group 'Osprey'
Verbascum bombyciferum, V. chiaxii 'Album', V. phoeniceum 'Violetta'
Verbena bonariensis AGM, V. hastata, V. rigida AGM
Veronica austriaca subsp. teucrium 'Crater Lake Blue' AGM, V. gentianoides
Viola cornuta
AGM, V. eliator cultivars
Zauschneria californica 'Dublin' AGM, Z. cana 'Sir Cedric Morris'

The vast majority of bulbs grow well in alkaline soils.
Most lilies prefer acid soils but some tolerant of alkaline conditions are listed below:

Lilium amabile var. luteum
L. bolanderi
L
. bulbiferum, L. bulbiferum var. croceum
l. candidum
L. × dalhansonii
L. davidii
L. duchartrei
L. hansonii
L. henryi
AGM
L. × hollandicum
L. lankogense
L. leucanthemum
L. longiflorum
L. martagon
AGM
L. monodelphum
L. pardalinum
AGM
L primulinum
L. pulmilium AGM
L. pyrenaicum
L. regale AGM
L. sulphureum

Ornamental Grasses

Although most grasses will thrive in well-drained sunny conditions, some particularly adaptable to dry, chalky or alkaline soils include:

Calamagrostis × acutiflora 'Karl Foerster'
Carex dipsacea, C. flacca 'Blue Zinger', C. oshimensis Everest = 'Fiwhite'
Elymus magellanicus
Eragrostis curvula
'Totnes Burgundy', E. elliottii
Festuca amethystina, F. glauca
'Elija Blue', F. glauca 'Intense Blue' (e)
Helicictotrichon sempervirens AGM
Juncus patens 'Carman's Grey', J. patens 'Elk Blue'
Miscanthus nepalensis, M. sinensis cultivars
Muhlenbergia rigens
Nassella trichotoma
Pennisetum alopecuriodes '
Hameln', P. 'Fairy Tails', P. orientale cultivars, P. macrourum
Poa labillardierei
Schizachyrium scoparium
Sesleria caerulea
Stipa gigantea AGM, S. tenuissima
(e)

Alpines

Alchemilla conjuncta, A. erythropoda
Androsase cylindrical, A. pubescens, A. pyrenaica
Anemone blanda
AGM, A. nemorosa AGM, A. pavonina
Arabis alpina
subsp. caucasica 'Schneehaube' AGM (e)
Arenaria montana AGM (e)
Armeria juniperifolia AGM
Artemisia schmidtiana 'Nana' AGM
Aster alpinus AGM
Aubretia (e)
Campanula 'Birch Hybrid' (e), C. carpatica AGM, C. cochlearifolia AGM
Cyclamen cicilium AGM, C. coum AGM, C. hederifolium AGM
Daphne cneorum 'Eximia AGM, D. × hendersonii 'Ernest Hauser' (e)
Dianthus alpinus AGM, D. anatolicus, D. 'Whatfield Cancan AGM
Dryas octopetala AGM
Erinus alpinus AGM
Erodium chrysanthum, E. manescavii
Gentiana aculis, G. septemfida, G. verna
Geranium cinereum
'Ballerina' AGM
Hepatica nobilis cultivars (e)
Iberis sempervirens 'Snowflake' AGM (e)
Incarvillea delavayi
Iris pumila, I reticulata
Jeffersonia diphylla, J. dubia
Lathyrus vernus
Lithodora diffusa
'Heavenly Blue' AGM (e)
Oenothera perennis
Origanum amanum
AGM, O. dictamnus
Oxalis adenophylla
AGM
Papaver alpinum, P. nudicaule
Phlox divaricata
'Clouds of Perfume'. P. 'Kellys Eye' AGM, P. subulata 'Purple Beauty'
Polygala calcarea 'Lillet' AGM
Pulsatilla vulgaris AGM
Ranuculus
Saponaria ocymoides AGM, S. × olivana AGM
Saxifraga 'Southside Seedling Group', S. 'Tumbling Waters' AGM (e)
Scutellaria suffrutescens 'Texas Rose'
Sedum
Sempervivum (e)
Thymus pulegioides 'Bertram Anderson' AGM, T. serpyllum 'Pink Chintz' AGM (e)
Veronica cinerea AGM, V. prostrata 'Spode Blue' AGM
Viola 'Belmont Blue', V. 'Columbine', V. 'Jackanapes' AGM, V. 'Maggie Mott' AGM (e)

Annuals 

Antirrhinum (snapdragon)
Alyssum
Arctotis
Brachyscome
Calendula
(pot marigold)
Celosia
Centaurea cyanus
(cornflower)
Convolvulus tricolor
Cosmos bipinnatus, C. sulphureus
Cynoglossum
Echium vulgare
(Vipers bugloss)
Eschscholzia (California poppy)
Felicia amelloides
Gazania
Godetia
Gomphrena
Gypsophila
Helianthus
(sunflower)
Lobelia erinus
Myosotis
(forget me not)
Nemesia denticulata AGM, N. 'Wisley Vanilla' AGM
Nicotiana affinis, N. langsdorfii, N. sylvestris, N. tabacum
Nigella damascena (love in a mist)
Papaver commutatum
 (ladybird poppy) , P. nudicaule, P. rhoeas (Shirley poppy), P. somniferum
Petunia
Phacelia campanularia, P. tanacetifolia
Salvia coccinea, S. farinacea, S. involucrata
AGM, S. patens AGM
Schizanthus (butterfly flower)
Tagetes (marigold)
Verbena
Zinnia

Advertise here

Video exclusive for RHS members: expert advice on dealing with slugs and snails

Sign into the RHS website to watch video Sign in

Sign in

Did you find the advice you needed?

RHS members can get exclusive individual advice from the RHS Gardening Advice team.

Join the RHS now

Discuss this

for the site or to share your experiences on this topic and seek advice from our community of gardeners.