How to make soil acidic for blueberries
Blueberries need pH 4.5 to 5.5. Sulphur gets ordinary soil there.
Above about pH 5.3, blueberries struggle to take up iron and the youngest leaves turn yellow. Most UK garden soil sits well above that. Work sulphur into the bed at least six months before planting, ideally a year, then keep it topped up.
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- Test first, then work out how far you need to go.
- Start the bed at least six months ahead, ideally a year: sulphur needs warm soil and time.
- In pots, skip sulphur: use ericaceous compost and rainwater.
How much sulphur for a blueberry bed
| Soil | From pH 6.5 to 5.0 | How to apply |
|---|---|---|
| Sandy | About 83 g/m² | Two doses, six months apart |
| Loam | About 165 g/m² | Three doses of 55 g/m², six months apart |
| Clay | About 260 g/m² | Five doses of about 52 g/m², six months apart |
| Established bushes | Up to 85 g a bush a year; never more than 25 g/m² a dose | Once in early autumn, or split between early spring and late autumn |
One and a half pH units at the rates on our product page (Ohio State, Purdue, University of California); established bushes: Oregon State, Cornell and University of Georgia. Scatter and water, then fork into the top 15 cm once the pastilles have broken up. On a bare bed, never more than 73 g/m² in one dose or 146 g/m² a year; over established roots, never more than 25 g/m² a dose. Loam and clay take a year or more to dose in full.
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.
Keeping it acid
- Rainwater only. Hard tap water raises the pH with every watering. A water butt pays for itself here.
- Mulch with bark. Composted bark keeps the shallow roots moist and adds no lime. It will not lower the pH on its own.
- Retest every autumn. Add sulphur only if the pH has crept above about 5.3, where yellowing starts: up to 85 g a bush a year, never more than 25 g/m² a dose (Oregon State; University of Georgia).
- On chalk, use containers. If your soil fizzes with vinegar, grow in large pots or a raised bed of ericaceous compost.
Common questions
Can I plant blueberries straight after adding sulphur?
You can, but the pH takes months to fall, and on loam or clay the full dose is spread over a year or more. Start at least six months ahead, ideally a year. If you cannot wait, plant into a wide pit of ericaceous compost and keep correcting the soil around it.
How long does sulphur take for blueberries?
It starts within weeks in warm, moist soil and takes a season to reach target. Retest after three to six months before adding more.
Do blueberries need sulphur every year?
Often, because tap water and soil minerals pull the pH back up. Retest each autumn and add sulphur only if it has crept above about 5.3: up to 85 g a bush a year, never more than 25 g/m² a dose.
Why are my blueberry leaves yellow with green veins?
Iron chlorosis: the pH is above about 5.3. Lower it with sulphur and switch to rainwater. See blueberry leaves turning yellow.
More: Sulphur Soil Acidifier · soil pH calculator · blueberry leaves turning yellow · how to make soil more acidic · what is ericaceous compost? · how to test soil pH
The right soil is most of a good blueberry crop
90% elemental sulphur in pastilles that spread without dust and break apart when wet. Work it in before planting; after that, up to 85 g a bush a year, at most 25 g/m² a dose.
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