Carol Klein's favourite plants for acid soil
Carol Klein shares her favourite plants to grow in acidic soil.
Having acid soil opens up a whole range of captivating plants you can grow.
It's worth testing the soil pH in your garden with a soil testing kit, so you know what you can and can't plant. Do this in a few spots around the garden, as the pH can vary depending on the other plants in the garden – for example the soil below trees is often made more acidic by falling leaves.
You can also see what grows well in gardens near yours to help determine if you have acidic soil. Hydrangeas will grow on most soils, but if the flowers are blue then the soil is likely acidic, while pink flowers indicate alkaline soil. Healthy-looking camellias, rhododendrons and hamamelis in the vicinity are are also a sign your soil is acidic.
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Check out Carol's top choices for acid soil, below.
It's worth testing the soil pH in your garden with a soil testing kit, so you know what you can and can't plant
Sanguinaria canadensis 'Multiplex'
A member of the poppy family, its leaves are similar to Macleaya cordata and its fully double flowers are pure white.
Flowers April to May.
Height x Spread 20cm x 15cm.
Primula 'Cowichan Venetian'
As a general rule, primroses prefer acid soil. The cowichan variety, with velvety petals and no disturbing bright centres, are particularly lovely.
Flowers March to May.
H x S 15cm x 20cm.
Trillium chloropetalum
Trilliums prefer neutral to acid conditions. This favourite has reptilian markings on the leaves and bracts and dark, three-petalled flowers.
Flowers April to May.
H x S 50cm x 50cm.
Cornus kousa var. chinensis
A flowering dogwood that relishes deep, acid soil. This variety has large, white bracts that are in bloom in late spring. It has good autumn colour too.
Flowers May to June.
H x S 4-8m x 4-8m.
Gaultheria procumbens
Gaultheria procumbens is a low-growing, evergreen sub-shrub. Its foliage colours up in the winter and is a delightful accompaniment to its red berries.
Flowers June to August.
H x S 50cm x 100cm.
Acer palmatum 'Osakazuki'
Most members of the acer family thrive on acid soil but need shelter from hot sun and wind. A slow-growing tree, 'Osakazuki' is ideal for a small garden.
Flowers April to May.
H x S 2.5-4m x 2.5-4m.
Magnolia sieboldii
More of a large shrub than a tree with big, pendulous white flowers opening to reveal a contrasting boss of maroon stamens. The flowers of Magnolia sieboldii are scented.
Flowers May to September.
H x S 4-8m x 8m.
Cercis siliquastrum
Cercis siliquastrum is also known as the Judas tree. Flower buds emerge from its bare branches before the leaves open to purple pea flowers. It needs sun and enjoys free-draining acid soil.
Flowers March to April.
H x S 8-12m x 10m.
Planting tips for acid soils
- Many acid-loving plants have fine roots and shallow rootballs, so prepare an area much wider than the rootball when planting
- Avoid digging a deep hole that may act as a sump
- Dig in plenty of organic matter, such as leaf mould, but not fresh, unrotted manure, which could burn the roots, or mushroom compost, which is highly alkaline
- After planting firm down to ensure the roots are in contact with the soil, but avoid being heavy-handed and don't use your feet
- Give plants a thorough drench after planting and water regularly in dry spells, ideally with rainwater if your tap water contains lots of lime
- Mulch around your plant with a homemade compost, bark or pine needles
- If leaves are yellowing it could be a sign the soil is too alkaline – try remedying this with an application of sequestered iron
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