What is ericaceous compost?
Ericaceous compost is lime-free compost for acid-loving plants.
It contains no lime, so it stays acid, usually around pH 4.5 to 5.5. Use it in pots for blueberries, camellias, rhododendrons, azaleas and pieris. In borders it is the wrong tool: a bag will not change the soil around it for long. To make border soil acid, use sulphur.
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- Pots: ericaceous compost and rainwater. No sulphur.
- Borders: sulphur changes the soil itself, for years.
- Planting hole: a mix of ericaceous compost and soil helps a plant establish while sulphur works.
Pots or borders?
| Ericaceous compost | Sulphur | |
|---|---|---|
| What it does | Gives acid-lovers an acid root run | Lowers the pH of the soil itself |
| Use it for | Pots, raised beds, planting pits | Borders and beds |
| How long it lasts | Two to three years before the pH creeps up | Years, topped up when a test says so |
| Speed | Straight away | A season |
| On chalky soil | The answer: grow in pots | Not realistic |
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
- Water with rainwater. Hard tap water adds lime with every can.
- Feed with an ericaceous feed. Ordinary feeds are fine for many plants but are not formulated for acid-lovers.
- Repot or refresh every two to three years. The compost breaks down and the pH creeps up.
- Do not add sulphur to pots. The RHS advises against sulphur in potting media.
Common questions
Can I use ericaceous compost for other plants?
Many plants cope with it, but it is too acid for lime-lovers such as lavender, clematis and most veg. Use multipurpose compost for those.
Can I make my own ericaceous compost?
You can get close with composted bark and leaf mould, with no lime or mushroom compost added. Test it before planting.
Is ericaceous compost peat-free?
Many now are, based on bark, wood fibre and coir; the bag will say. Peat is no longer recommended for acidifying soil (RHS).
Can I dig ericaceous compost into my border instead of using sulphur?
It helps a new plant settle in, but the surrounding soil soon wins. For a lasting change, lower the border pH with sulphur.
More: Sulphur Soil Acidifier · soil pH calculator · how to make soil more acidic · soil for blueberries · camellia leaves turning yellow · azalea leaves turning yellow
For borders, change the soil itself
90% elemental sulphur in pastilles that spread without dust and break apart when wet. Not for pots; this is for beds and borders.
Buy the size for your border
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.