Posted on Sunday, May 1st, 2016
Gardening on chalky soils can be a challenge. The soil itself tends to be shallow due to ongoing erosion and the porous nature of chalk makes it very well draining – so drought tolerant plants will cope best. Added to that, chalk has a high lime content so the soil tends to be alkaline, but on flat ground with deeper topsoil the porosity of the chalk can actually leach out all the lime, leading to acidic conditions. The leaching effect can also wash out nutrients from the soil.
So if you have chalky soil it’s likely to be shallow, dry, alkaline (or acidic) and nutrient poor! But don’t despair, there are plenty of plants that are up to the challenge.
Trees and shrubs
Chamaecyparis lawsoniana
This conifer will tolerate most conditions, although it prefers a sunny spot. It’s a good choice for hedging in a chalky garden or, if you want an architectural shrub, try Chamaecyparis lawsoniana ‘Erecta Aurea’ (shown here) which grows to only 2 metres tall. It has a compact, conical shape and bright yellow/green foliage.
Cornus mas
Growing up to 4 metres tall, the ‘Cornelian cherry’ is actually a species of dogwood and some varieties have the brightly coloured young stems typical of this genus of plants. It can be grown as a shrub or small tree and is prized for the bright yellow blossom which appears on bare stems in late winter.
Berberis darwinii
This dense, evergreen shrub will grow to 2.5 metres height and spread and is happy in any soil so long as it isn’t waterlogged – so chalk is ideal. Bright orange flowers appear in the spring followed by blue/black fruit in the summer. It requires little maintenance, which is good because the stems are covered in very sharp thorns!
Against a wall
Clematis
These climbers prefer a slightly alkaline soil and are happy on growing on chalk. If you want to cover a wall or shed then Clematis montana var. rubens ‘Tetrarose’ is a great choice. It will climb up to 8m metres and bears violet coloured flowers with yellow centres throughout the summer. Keep its roots cool by mulching well.
Jasminum nudiflorum
The winter jasmine is an excellent partner plant for clematis as it provides winter interest with small yellow flowers appearing in winter and early spring. It doesn’t ‘climb’ like the clematis does, so its gracefully long stems will need to be tied into a support.
Herbaceous plants
Paeonia
Peonies often work well on chalk soils. Paeonia lactiflora ‘Sarah Bernhardt’ is a popular choice. It grows to about 1 metre height and spread and has large, pink double flowers in the summer. Peonies prefer a sheltered spot and will require support as they grow.
Dianthus
Pinks are happiest in well drained and neutral to alkaline soils, so are an ideal choice on chalk. Try Dianthus ‘Doris’ for pale pink flowers over a compact mound of grey/green foliage. It looks great at the front of a bed or border.
Helenium
Perennial ‘sneezeweeds’ such as Helenium ‘Moerheim Beauty’ (shown here) are happy in any soil and cope well with chalk. Their daisy-like flowers appear in summer and are a perfect selection for hot borders. Taller varieties will require support.
Crocus
Preferring well drained soil, crocuses are a good plant for spring colour on chalk soil. Crocus chrysanthus ‘Cream Beauty’ will work well and reward you with creamy flowers that are deep yellow in the centre, from early spring.
Use our plant selector to search for more ideas for chalky soils.
