What to grow by soil type

Each and every garden consists of a mixture of different micro-environments. No two gardens offer exactly the same conditions, and this is one of the reasons why gardening is such an exciting hobby.

The soil is the starting point for successful gardening. The old saying ‘The secret lies in the soil’ couldn’t be more right! Your soil type is fundamental in dictating what varieties of plants can be grown and the first thing you need to do is establish which soil you’ll be working with. There are four main types: clay, sand, loam and chalk. The best way to tell which soil you have in your garden is to pick some up and mix it with a little water in the palm of your hand, trying to work it into a small ball.

Clay soils

• Feel sticky and will work into a ball when mixed with water
• Are difficult to work in wet or very dry weather
• Are cold and wet in winter but may bake dry in summer
• Are slow to warm up in spring
• Mostly high in nutrients although some trace elements can be ‘locked up’ by attaching themselves to the clay particles

Sandy soils

• Feel gritty and will not hold together when mixed with water to make a ball
• Are easy to dig even during wet weather
• Are free draining in winter but become dry and dusty in summer
• Warm up quickly in spring
• Leach nutrients quickly due to the free draining nature of these soils
• Sandy soil is often acidic

Loamy soils

• Are between clay and sandy soils. The soil may hold together when rolled into a ball if it is a ‘clay loam’ but won’t if the soil is a ‘sandy loam’
• Loam soils with a high clay content are known as ‘heavy clay loam’ and those with a high sand and silt content are ‘sandy loam’
• Are easy to dig once the surface has dried out
• Hold nutrients well and tend not to ‘lock up’ trace elements

Chalky soils

• Lumps of white chalk or flint stones are visible in the soil
• Are either ‘heavy’ or ‘light’ depending if the soil mixed with the chalk is clay or sand

Alkaline soils

• The soil fizzes when added to malt vinegar, showing the calcium carbonate content
• These soils are often ‘shallow’ with little depth of top soil

Once you have established the type of soil that you have, look at the types of existing plants that are growing in your garden or in nearby gardens. Are there lots of Rhododendrons, Azaleas and Camellias, along with Pine trees and blue flowers on Hydrangeas? This is a sure sign that the soil is acidic – a must for ericaceous plants.

pH 3.0 to pH 5.0

• Very acidic soil
• Nutrients are either more soluble, therefore washed away easily, or ‘locked up’ making them unavailable to plants. These soils are deficient in nutrients
• Most plants find it difficult to grow in very acid soil
• Top tip! Add lime to raise the pH to 5.0

pH 5.1 to pH 6.0

• Acid soil
• Ideal for lime hating (ericaceous) plants such as Camellias, Heathers, Azaleas and Rhododendrons
• Add lime if other plants are grown and for vegetables and fruit

pH 6.1 to pH 7.0

• Moderately acid soil
• This is the ideal pH for a wide range of plants, except lime hating plants
• It is not usually necessary to add anything to the soil to change the pH

pH 7.1 to pH 8.0

• Alkaline soil
• Iron and manganese become less available to plants leading to yellowing of the leaves (chlorosis)
• Iron sulphate and other acidifying agents can be added to reduce the pH. Chalky soils are usually not treatable

These soils tend to be found around the great chalk downs in the southern half of Britain. Characterised by being well drained, but with high pH, a particular set of plants has developed to make the most of the conditions. These plants will give excellent results on chalky soils:

Trees

• Acer campestre
• Acer cappadocicum forms
• Acer griseum
• Acer Negundo forms
• Acer platanoides and forms
• Acer pseudoplatanus and forms
• Aesculus (Horse Chestnut)
• Gingko biloba
• Populus alba
• Betula

Shrubs

• Buddleja
• Ceanothus in variety
• Pyracantha
• Chaenomeles
• Chimonanthus
• Forsythia suspense
• Escallonia in variety
• Hedera

Clay soils are common across Britain. They tend to be heavy to work, but are frequently rich in nutrients. Gardening on clay can be back breaking to begin with, but with the generous and frequent addition of garden compost and other organic matter, over the years these can be some of the most productive and rewarding soils. Very many garden plants will happily flourish on clay soils, having evolved root structures which are designed to cope with Britain’s most common soil type. We suggest:

Trees

• Acer in variety
• Malus
• Alnus in variety
• Betula, some varieties
• Prunus
• Corylus
• Crataegus
• Sorbus
• Fraxinus

Shrubs

• Potentilla
• Berberis
• Chaenomeles
• Prunus Lusitanica
• Pyracantha
• Corylus
• Spiraea
• Hedera
• Kerria
• Weigela
• Chaenomeles
• Viburnum x burkwoodii
• Euonymus fortunei
• Forsythia

Conifers

• Abies
• Taxus
• Crytomeria
• Taxodium

These soils have a low pH and are frequently peaty in texture. Gardeners on lime free soils are usually envied by other less fortunate gardeners since they are able to grow a range of the extravagantly showy plants. Those magical words: Camellias, Rhododendron, Azalea and Ericas – all these plants are taken for granted by lime free soil gardeners. For the rest of us, the plants below are best grown in planters containing ericaceous compost, or in the garden in deep man-made pockets of the same stuff. You could try:

Shrubs

• Camellia
• Kalmia
• Leucothoe
• Skimmia
• Corylopsis
• Magnolia
• Enkianthus
• Fothergilla
• Rhododendron
• Azalea
• Gaultheria
• Hamamelis

Poorly drained soils normally mean that for long periods the water content of the soil is very high. But, as always, nature has found a solution and a range of plants have evolved whose root systems are quite content to remain wet. Our list features plants whose ancient forebears would commonly be found in swamps, marshes and along riverbanks. Consider growing:

Trees

• Acer pseudoplatanus
• Pyrus
• Alnus
• Quercus robur
• Carpinus betulus
• Salix
• Populus

Shrubs

• Cornus stolonifera varieties
• Sambucus
• Salix

Conifers

• Metasequoia
• Taxodium

Wet sites and even swampy conditions can be successfully and attractively planted. Many British native plants originally grew in just such conditions and are well represented in our list of plants. Dogwood, Willow, Ornamental Elders and Mock Orange will all thrive and give an excellent show. Those suitable for swampy conditions are marked (SS).

Trees

• Acer negundo
• Alnus
• Betula nigra
• Fraxinus excelsior
• Liriodendron
• Mespilus germanica
• Parrotia
• Salix (SS)
• Sorbus aucuparia forms

Conifers

• Abies
• Cedrus deodara
• Metasequoia
• Taxodium

Shrubs

• Amelanchier
• Hydrangea
• Parrotia persica
• Philadelphus in variety
• Physocarpus opulifolius
• Rhododendron
• Salix in variety (SS)
• Spiraea in variety
• Viburnum rhytidophyllum

Perennials

• Astilbe
• Lobelia Russian Princess
• Caltha
• Primula in variety
• Hosta
• Trollius
• Ligularia

Sometimes known as ‘nurseryman’s soil’, these soils can be some of the most productive in the country, if properly watered and fertilised. Light sandy soils are quick to warm up in the spring, seldom become waterlogged and are easily worked. The secret of success is never to let the soil become too dry and ensure that good levels of plant food are available.

Trees

• Acer campestre
• Cercidyphyllum
• Acer negundo varieties
• Cercis
• Acer platanoides
• Eucalyptus
• Acer pseudoplatanus
• Gleditsia
• Populus alba forms
• Alnus cordata
• Betula
• Quercus ilex
• Robinia

Shrubs

• Hypericum
• Artemisia
• Berberis
• Mahonia aquifolium
• Ceratostigma
• Cistus
• Clerodendrum
• Potentilla
• Cortaderia
• Romneya
• Cotoneaster Ground Coverers
• Salvia

Low to medium growing varieties

• Sambucus
• Cytisus
• Genista
• Spiraea
• Halimum
• Helichrysum

Whatever soil you have, understanding it is an engaging and exciting challenge that adds to the enjoyment of gardening. There really is something for every type of soil – and remember soil which is good in heart and high in nutrients will offer plentiful rewards of beautiful flowers and bountiful fruit and vegetable crops.