The 16 Most Asked Questions About Ericaceous Compost

When it comes to the different kinds of compost for the garden, many people start feeling a little out of their depth. Few of us are experts on soil types and what plants need which nutrients, and if you’re starting to look at ericaceous compost, you might have some questions about it.

1. What Is Ericaceous Compost?

This is a kind of compost that is acidic and it is specifically designed for use around plants that dislike alkaline soil. Ericaceous compost isn’t suitable for most growing, but if you have plants that require it, the chances are that you won’t be successful with them unless you use it.

The name of this compost comes specifically from the plants that it’s used for – those in the Ericaceae family. These plants are known for requiring acidic soil and struggling in higher pH soil. If you have any of these plants, you’ll need to get some ericaceous compost for them whenever they need a nutrient top-up!

2. How Do You Make Ericaceous Compost?

You might be wondering if you can make ericaceous compost at home or if you have to buy it. The great news is that you can make it yourself, in a similar way to making standard garden compost. If you already have a compost pile, you may even be able to adapt it to produce ericaceous compost, or you might want to start a separate pile for it.

To make your compost ericaceous, you need to increase its acidity. You also need to avoid adding lime to the pile (or other high alkaline ingredients).

Common waste that you might have which will make your compost more acidic includes:

  • Coffee grounds
  • Pine needles
  • Oak leaves
  • Sawdust
  • Citrus peels

You can make your compost almost normally, and only start adding these acidic ingredients (and cutting back on alkaline ingredients) toward the end. As long as the final result has plenty of acid in it, you have ericaceous compost.

You need to keep testing the pH of your compost, as its acidity will go down over time, and you will need to add more acidic ingredients to ensure it stays suitable for your plants.

3. What Is The pH Content Of Ericaceous Compost?

There is not a fixed pH that ericaceous compost must be, but to be acidic, it usually needs to have a pH between 4.0 and 5.0. At 7.0, the pH is neutral, so anything much higher than 6.0 will likely not provide the acidity that the plants need, and wouldn’t be classed as ericaceous compost.

To test the pH of the compost, you can purchase a pH testing kit very inexpensively. These are readily available online, and will let you know whether your compost is suitable for use.

4. Is Ericaceous Compost Acidic?

Yes, ericaceous compost is, by definition, acidic. If you add alkalinity to ericaceous compost, it becomes ordinary compost. It must have a low pH value to count as ericaceous and be suitable for plants in this family.

5. Can Ericaceous Compost Be Used For All Plants?

Ideally, no, you shouldn’t use neat ericaceous compost for all your garden plants without checking their requirements; different plants prefer different growing conditions. If your plants are lime-lovers, they will not grow well (if at all) in ericaceous compost, and they may die because of the high acidity levels in the soil.

However, if you have ericaceous compost to hand, it’s rarely an issue to mix it with other compost. The other compost will bring the pH up somewhat, reducing the acidity, and balancing it out to make a suitable growing medium for almost all plants.

Many plants that are not in the Ericaceae family will still grow in ericaceous compost, but they may not thrive. You can always try and see what happens, but on the whole, garden plants that are not members of this family prefer higher pH values and will grow better in standard compost.

If you are just using ericaceous compost as a soil improver, you will probably have the same results. Most plants will grow with it (although a few alkaline-lovers may struggle), but they would do better with normal compost with a balanced pH level.

6. Do Acers Need Ericaceous Compost?

Acers do not need ericaceous compost as such, but many will grow better if you provide it. That is because the acers do need many of the minerals (such as iron) that tend to be bound up in lime molecules in ordinary soil.

If you plant an acer in a standard pH or high alkalinity soil, they may not be able to access these minerals readily. You will probably find that they struggle to grow, or grow much more slowly, so it’s best to plant them with ericaceous compost if possible.

Remember that the acid in the soil washes away over time, so you should mulch the surface around your acer’s roots with ericaceous compost every so often to ensure it is still able to access the minerals it needs.

7. Do Hydrangeas Need Ericaceous Compost?

Hydrangeas are a plant that is famous for producing different colored blossoms depending on the type of soil that they are in. If you have ever observed the amazing difference between pink hydrangeas and blue ones and wondered what causes it – it’s the compost.

That means you might buy a stunning blue hydrangea at a garden center, only to have it turn pink once you’ve got it settled in your garden. That obviously isn’t ideal, and you can solve it by giving your hydrangea plenty of ericaceous compost and increasing the acidity of its growing medium.

However, if you want pink or white hydrangeas, alkaline soil is fine. Your hydrangea will grow just as well in non-ericaceous compost, but it won’t provide that stunning, rich blue color.

8. Do Camellias Need Ericaceous Compost?

Yes, camellias need ericaceous compost to grow well. They are acid-loving plants, and will not thrive if you plant them in ordinary soil. High alkaline content and too much sunlight are sure ways to kill your camellia plant, so make sure that you have some ericaceous compost available if you want to grow these beautiful pink blossoms.

Remember that you can plant in pots to make it easier to supply ericaceous compost to plants like this. A camellia will grow perfectly happily in a pot, and you won’t have to alter the soil pH to keep it acidic enough for your plant as often as if they grow in the ground.

9. Do Magnolias Need Ericaceous Compost?

Magnolias prefer slightly acidic soil, and will not do so well if you plant them in alkaline soil. You should test the pH of your garden before purchasing a magnolia, and decide whether it is suitable.

If it isn’t, don’t despair; some magnolia varieties can be grown in containers. However, as they are large plants, you will need to make sure that the one you choose is suitable for this, or it may die.

If your soil is higher than a 5.0 pH, a magnolia will probably still grow happily enough. They do not require extremely acidic soil, but may struggle if you have a very high pH value.

It is best to test the specific spot where you intend to put the magnolia, and then go from there. If you plant your magnolia straight into the ground, be prepared to mulch it with ericaceous compost every year or so to ensure that the pH value stays low. This is the best way to ensure you get beautiful blooms year after year!

10. Do Peonies Need Ericaceous Compost?

Peonies are not particularly fussy plants, and if you are looking to grow them in your garden, you probably won’t need ericaceous compost unless you have quite alkaline soil.

They like neutral to slightly acidic, so you shouldn’t need to add ericaceous compost or other forms of acid if your ground is already a relatively neutral pH. It is still worth checking before you plant, however, as your peony will not thrive in highly alkaline soils.

11. Do Clematis Need Ericaceous Compost?

No, a clematis plant does not require ericaceous compost to grow well. Clematis plants will tolerate most soil pHs (though some may struggle with extreme values), but they do like good soil.

That means you should add plenty of feed or fresh compost of any sort to the soil before you plant the clematis. It is a fairly hungry plant, and you may want to provide it with fertilizer every few years to ensure you get a flush of those gorgeous and heavily scented flowers.

12. Do Azaleas Need Ericaceous Compost?

Azaleas will grow in neutral soil, but they prefer to be on the acidic side of the scale. They do not do well in alkaline soils, so it’s better not to grow them directly in the ground if your garden has lots of lime in it.

It’s a good idea to check your soil’s acidity level before you purchase azaleas to grow. They can also be grown in pots if your garden is not suitable, and these can be fed with an ericaceous fertilizer to keep the soil suitably acidic.

13. Does Pieris Need Ericaceous Compost?

Yes, Pieris require ericaceous compost to grow well, so if your garden is alkaline, you will need to plant them in a container full of ericaceous compost. They like rich and well-drained soil, and will grow well with an annual mulch of pine needles.

You do not have to provide this mulch, but if the soil reverts to alkaline and the Pieris doesn’t have enough acidity around its roots, it may die back or completely die. Keep an eye on the pH of the soil around your Pieris, and be prepared to make corrections to keep it acidic.

14. Does Ericaceous Compost Contain Peat?

Traditionally, ericaceous compost has contained high amounts of peat, because peat is naturally acidic and rich, so it’s a great addition to ericaceous compost. However, growing awareness of the damage that harvesting peat causes to the environment means that things are changing.

If you are making your own ericaceous compost, you of course do not have to (and probably would not want to) include peat, but if you’re looking to purchase some, you may need to hunt a bit to find a peat-free ericaceous compost. There are some available, which use wool, bracken, bark, or coconut coir.

15. Where Do You Buy Ericaceous Compost?

Most garden centers and nurseries will stock ericaceous compost, or it can be purchased online. It is often more expensive than standard compost because it has to be made in a particular way, so you may wish to make your own at home. However, you will find it readily available if you would rather buy it.

16. What Can I Use If I Don’t Have Ericaceous Compost?

There aren’t really any substitutes for this kind of compost if you need it as a growing medium. For example, if you want to fill a container or a hole you intend to plant in, you need ericaceous compost if the plant requires acidic growing conditions.

However, if you are just mulching around the top of a plant, you can use other acidic substances instead, and allow them to break down into the ground. The acidity will filter down and make the soil more acidic.

Things that work well for this include pine needles, citrus peels, and sawdust. You can also treat soil with vinegar, but you should dilute it heavily as its strong acidity will quickly kill plants (and many people use it deliberately to kill weeds). In general, about one cup to a gallon of water will be suitable.


Ericaceous compost is a useful component in gardening, especially if you wish to grow any of the plants on this list. Understanding how and when to use it, as well as how to make it, is very valuable to a gardener.

While the basics of gardening can be understood as providing enough water and sunlight, knowing what kind of soil your plant likes to grow in and what kind of soil you have can take your horticultural ventures to the next level.