Revision Notes

Soil Indicators

Indicator species are also sometimes known as Soil Indicators. They are so characteristic of certain types of soil condition – either soil type or pH – that their simple presence can be used as an important clue as to the nature of the soil.

It is more difficult to use soil indicators in an established, well-maintained garden, but even there, the sorts of weeds and problems the gardener reports can give some important clues as to soil type.

Rhododendrons and azaleas, for example, will thrive in acid soil but look sickly and yellowing in alkaline soils. Similarly, many forms of Viburnum prefer chalky, alkaline conditions.

common soil indicators

Viburnum – chalky, alkaline soil

Heather – dry, acid or peaty soil

Nettle, chickweed – potentially fertile soil

Catnip (catmint) – chalky or alkaline soil

Sheep’s sorrel – poor, light, dry, acid soil

Foxglove – dry, sandy or gravely soil

Wild strawberry – dry, stony soil

Gorse or broom – poor, infertile soil

Coltsfoot – damp, clay soil

Wild thyme – dry soil

Common butterwort, lesser spearwort – wet, fertile soil

Goldenrod – wet sand

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