Ericaceous compost is simply compost with a low, acidic pH, made for the group of plants that cannot cope with lime. If you have ever potted a healthy camellia or a blueberry into ordinary compost and watched it slowly yellow and sulk, this is almost certainly why. Get the compost right and those same plants stay deep green and thrive. Here is what ericaceous compost actually is, which plants need it, whether roses want it, and how to use it well.
By Kel Dickson, Senior Brand Marketing Manager at Gro Worm, organic, peat-free grower. Reviewed by Brian McCuskey. Updated August 2026.
What is ericaceous compost?
Ordinary multipurpose compost sits close to neutral, around pH 6.5 to 7, which suits most plants perfectly well. A group of plants known as ericaceous or calcifuge plants cannot cope with that. They evolved on acidic woodland and moorland soils, and in neutral or alkaline conditions their roots simply cannot take up the nutrients they need, particularly iron. Ericaceous compost is formulated with a lower pH, usually around 4 to 5, to recreate those acidic conditions so the plants can feed properly.
The name comes from Ericaceae, the plant family that includes heathers, rhododendrons and blueberries. In practice the term now covers any plant that needs acidic conditions, whether or not it belongs to that family botanically.
Which plants need ericaceous compost?
The main ones are rhododendrons, azaleas, camellias, blueberries, cranberries, heathers, pieris, magnolias and skimmia. Japanese maples, usually sold as acers, also do considerably better in acidic conditions, which is why acer feed and ericaceous feed are often one and the same.
Hydrangeas are the interesting exception. They will grow perfectly well in ordinary compost, but soil pH controls their flower colour. In acidic conditions the plant can access aluminium and the flowers turn blue; in neutral or alkaline conditions they come out pink. So if you want blue hydrangeas, ericaceous compost is how you get them, and you will need to keep the pH down year after year rather than doing it once.
Can I use ericaceous compost for roses?
No, and this is one of the most common questions we get. Roses are not acid-loving plants. They prefer a neutral to slightly acidic soil, roughly pH 6 to 6.5, which is exactly what a good peat-free multipurpose, rose or John Innes compost provides. Growing roses in ericaceous compost pushes the pH too low and can cause the very nutrient problems you are trying to avoid, leaving you with weaker growth and poorer flowering. Save the ericaceous bag for the genuine acid-lovers on the list above, and pot your roses into a general-purpose mix instead. If you want to feed them gently, our guide to worm castings for roses covers it.
Why do acid-loving plants turn yellow?
Yellowing leaves with green veins is almost always lime-induced chlorosis, and it is a nutrient access problem rather than a nutrient shortage. When the pH around the roots is too high, the iron in the compost becomes locked into a form the plant cannot absorb. The iron is there. The plant simply cannot reach it.
The leaves lose their chlorophyll and pale from the edges inward while the veins stay green, which is the classic signature. Left long enough, growth slows and flowering suffers. If you are gardening in a hard water area, it is worth watering with collected rainwater where you can, because tap water carries dissolved lime that gradually raises the pH in the pot and undoes the compost you started with.
How to use ericaceous compost
For containers, choose a pot at least a third wider than the root ball and make sure it drains freely, since acid-loving plants dislike sitting in water almost as much as they dislike lime. Fill the base with ericaceous compost, sit the plant so the top of the root ball is level with the surface rather than buried, then fill around the sides and firm gently before watering in thoroughly.
For plants going into open ground, dig a generous hole and backfill with ericaceous compost mixed into the native soil. Be realistic, though. If your garden soil is naturally alkaline, a pot is a far more reliable long-term home than a border, because the surrounding soil will gradually pull the pH back up whatever you add.
When it comes to feeding, use a dedicated ericaceous feed from early spring through to late summer while the plant is actively growing, and stop over winter when it is dormant. Ordinary plant foods are formulated for neutral conditions and will slowly raise the pH in the pot, so they work against the compost. Rhododendrons, azaleas and camellias set next year's flower buds shortly after this year's flowers fade, so the weeks straight after flowering are the most valuable time to feed.
What makes Gro Worm ericaceous compost different
Most ericaceous composts stop at getting the pH right. Ours goes further in two ways. First, it is enriched with pure worm casts, which improve the structure of the compost, help it hold moisture without becoming waterlogged, and make nutrients more readily available to the plant. Second, we add iron directly, so that the one nutrient acid-lovers struggle most to reach is there in a form they can use, working alongside the low pH to keep foliage a healthy deep green. You can see the full range on our ericaceous compost collection.
If you want to understand the worm cast side of that in more detail, it is the same thinking behind our Black Gold peat-free compost: feed the plant and improve the living soil at the same time, the natural way.
Frequently asked questions
Can you use ericaceous compost for lemon trees?
No. Citrus such as lemons, limes and oranges prefer soil that is slightly acidic to neutral, roughly pH 6 to 6.5, which is a long way from the pH 4 to 5 of an ericaceous blend. Potting a lemon tree into ericaceous compost pushes the pH lower than the tree wants and brings on the very nutrient problems you were trying to avoid. Use a dedicated citrus compost instead, and our guide to citrus compost covers what lemons, limes and oranges actually need.
Can I mix ericaceous compost with normal compost?
You can, but it is worth understanding what happens when you do. Mixing in multipurpose compost raises the pH of the blend, so the more you add the less acidic it becomes and the less use it is to a genuine acid-lover. For the fussy ones, particularly blueberries, camellias and rhododendrons in pots, use ericaceous compost neat. Where mixing does earn its place is in open ground, where backfilling a planting hole with ericaceous compost worked into the native soil gives the roots a better start than the surrounding soil would on its own.
Is ericaceous feed the same as ericaceous compost?
No. The compost is the growing medium the plant sits in, and the feed is the nutrition you add through the growing season once the compost's own reserves run down. The same plants need both, which means rhododendrons, azaleas, camellias, blueberries, cranberries, heathers, pieris, magnolias, skimmia and acers. The important part is to use an ericaceous feed rather than a general plant food, because ordinary feeds are formulated for neutral conditions and will slowly raise the pH in the pot, working against the compost you started with.
Do succulents like ericaceous compost?
No. Succulents and cacti are not acid-lovers, and their problem is drainage rather than pH. They want an open, gritty mix that dries out quickly between waterings, which is not what an ericaceous compost is built to do. Our guide to cactus and succulent compost explains what they need instead.
Ready to switch?
If you are growing anything on the acid-loving list, the simplest fix is to start it in the right compost. Our Gro Worm ericaceous compost is certified organic, enriched with worm casts and boosted with iron, so your camellias, blueberries and rhododendrons get the acidic, well-fed conditions they need to stay green and flower well.
