Ericaceous soil explained – What is ericaceous compost?

What is ericaceous compost?

Ericaceous compost, or ericaceous soil, is a type of specialist acidic compost named after the ‘ericaceae’ family of plants that like to grow in it.

Some plants are referred to as ‘ericaceous’ or ‘lime-haters’. It means that these ericaceous plants find it difficult to grow in non-acidic alkaline soil that has a pH value above 6. They find it difficult to take up nutrients and eventually the leaves will turn yellow and often they can die. As a result, these acid-loving or lime hating ericaceous plants need a more acidic compost to thrive.

So, you have just bought a beautiful plant from the garden centre and brought it home only to read on the label that it will need to be planted in ericaceous compost - but what does that mean exactly? Read on to find out all my tips and advice on what ericaceous compost is and how to care for ericaceous plants your garden.

Author

David Domoney

Chartered Horticulturalist, Author and Broadcaster

Which plants need an ericaceous compost?

The most popular type of plants that need to be grown in an ericaceous compost include:

Rhododendrons and Azaleas
Camellias
Pieris japonica
Gaultheria procumbens
Japanese maples (Acer)
Some Magnolias
Liriope muscari
Heathers.

There are also some fruits that need or prefer an acidic soil, including Blueberries, Raspberries and Cranberries. This list isn’t exhaustive so do make sure you research your plant to be sure what type of compost it needs!

Why do ericaceous plants need ericaceous compost?

If you try to grow ericaceous plants in alkaline or lime soils, they’ll produce yellow leaves in a condition known as lime-induced chlorosis. They don’t grow or flower well and usually die off eventually. The main reason for this is that they need iron and other soil nutrients and if the soil is high pH, these become insoluble or ‘locked up’ in the soil so the plants can’t absorb them.

Sometimes the type of plants that are growing in yours or your neighbour’s garden will indicate the type of soil you have so if there are lots of healthy rhododendrons and camellias growing in the area then you can be fairly certain that you have acidic soil. If it’s not obvious then you can do a simple test to find out the pH value of your soil with a kit or metre you can buy from most garden centres.

If you find you have mainly alkaline soil (lime-based) then it will be much better to grow these plants in pots and containers filled with special ericaceous compost rather than to try and change your soil type.

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Miracle-Gro^® Peat Free Premium Azalea, Camellia & Rhododendron Ericaceous Compost

Pink Rhododendrons are ericaceous plants that need ericaceous soil

How to use ericaceous compost to care for and grow ericaceous plants

Many ericaceous plants are woodland plants and therefore prefer to be out of direct sunlight as their flowers and leaves can be scorched. That makes them perfect plants for growing in shade or partial shade.

If you’re planting something like a large Rhododendron or Magnolia then try to use a big container making sure it has drainage holes.

Add some broken pots to the bottom and then fill the container with a good quality, peat free ericaceous compost.
Add the ericaceous plant, keeping the depth to the same level as in its original pot and then add more compost to the sides, pressing down as you go.
Make sure you leave enough room to water well as many ericaceous plants are shallow-rooted so will need decent watering.

Good quality ericaceous composts contain suitable feed that lasts 3 months but make sure after this time that you feed your container plants with an ericaceous feed such as Miracle-Gro Concentrated Liquid Plant Food and plants in beds and borders will benefit from a continuous release plant food, which feeds for 6 months from just one application.

Although most ericaceous plants flower in early to late spring, you’ll need to regularly water them, especially during the summer period. After watering it’s a great idea to add mulch to the top of the compost to help retain moisture.

Hopefully this has helped to demystify what ericaceous compost is and enable you to grow healthy and happy ericaceous plants in the right place.