Acidic soil: how to tell and what to do
Acidic soil is below pH 7. Whether it matters depends on what you grow.
Acid soil is common: more than 40% of UK arable soils and over half of grassland sit below their target pH (Holland et al., 2018). Rhododendrons thriving next door, moss with sheep's sorrel in the lawn and clubroot in brassicas all point that way, but only a test settles it. For veg and lawns, lime raises the pH. For blueberries and camellias, acid soil is an asset.
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- Acid signs: rhododendrons, camellias and heathers doing well; moss and sorrel in lawns.
- Alkaline signs: soil that fizzes with vinegar, chalk or flint in the soil, yellowing acid-lovers.
- Too acid for what you grow? Lime raises the pH. Just right for acid-lovers? Leave it alone.
Signs to look for
| Sign | Points to | Next step |
|---|---|---|
| Rhododendrons, camellias and heathers thriving in neighbouring gardens | Acid | Test before liming |
| Moss and sheep's sorrel in the lawn | Acid, often | Test; lime a lawn only below 5.5 |
| Clubroot in cabbages and sprouts | Acid soil makes it worse | Lime the brassica bed |
| Soil fizzes with vinegar | Alkaline, with free lime | No lime; pots for acid-lovers |
| Acid-lovers with yellow leaves and green veins | Too alkaline for them | Sulphur in the ground |
Signs are only clues: moss also comes from shade and wet, and plants can be in imported soil. Test before you treat: see how to test soil pH.
Plants that love acid soil
| Plant | Target pH |
|---|---|
| Blueberries and cranberries | 4.5 to 5.5 |
| Rhododendrons, azaleas, pieris | 4.5 to 6.0 |
| Camellias | 5.0 to 6.5 |
| Blue hydrangeas | 5.5 or below |
| Most veg, fruit and lawns, for comparison | 6.0 to 7.0 |
RHS; Cornell; University of Georgia, as on our Sulphur Soil Acidifier page.
If it is too acid for what you grow
Lime beds to about pH 6.5 and lawns to about 6.0. On loam that is about 0.5 kg per m² from pH 6.0 and 0.8 kg from 5.5 (RHS); full table in how to raise soil pH.
Work out your exact amount. Enter your area, your test reading and your soil type, and the calculator gives the dose, the timing and the bags to buy.
Common questions
What makes soil acidic?
Rain slowly washes calcium out, especially on sandy soil and in wetter western areas. Soils over sandstone, granite and heathland are acid by nature, and ammonium-based fertilisers add to it over time.
Is acidic soil bad?
Only for what you grow. Most veg and lawns want 6.0 to 7.0, but blueberries and rhododendrons need it acid.
Does moss mean my soil is acidic?
Not on its own. Moss grows in shade and on wet or compacted lawns at any pH. Moss with sheep's sorrel is a stronger hint. Test before you lime; see does lime kill moss?
How do I fix acidic soil?
Add garden lime, at about 0.4 to 1.8 kg per m² for beds depending on soil type and how acid it is, and less on lawns. Test first.
What grows well in acidic soil?
Blueberries, rhododendrons, azaleas, pieris, camellias and summer heathers. Hydrangeas flower blue on it.
More: Granulated Lime · soil pH calculator · how to test soil pH · how to raise soil pH · does lime kill moss? · how to make soil more acidic
Correct the soil to suit what you grow
Calcium carbonate granules that spread without dust and fall back to fine lime when wet. Lime to the test, not by habit.
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Free UK delivery over £40. Buy now goes straight to checkout.
Free UK delivery over £40. Dispatched in 1 to 2 working days. Packed and posted from Stockport.