What Is Ericaceous Compost And When Should You Use It? Gardeners Reveal All
Elizabeth is a Permaculture Garden Designer, Sustainability Consultant and Professional Writer, working as an advocate for positive change. She graduated from the University of St. Andrews with an MA in English and Philosophy and obtained a Diploma in Applied Permaculture Design from the Permaculture Association.
Reviewed By COLIN SKELLY
Colin is a Horticulturist and Horticultural Consultant with experience in a range of practical and managerial roles across heritage, commercial and public horticulture. He holds the Royal Horticultural Society’s Master of Horticulture award and has a particular interest in horticultural ecology and naturalistic planting for habitat and climate resilience.
IN THIS GUIDE
If you want to grow acid-loving plants in your garden, then ericaceous compost provides an ideal environment for them to flourish.
You may have heard of ericaceous compost even if you’ve never used it in your garden. The pH balance of ericaceous compost makes it perfect for growing acid-loving plants.
Some of the most beautiful species of plants need acidic soil to thrive, so having ericaceous compost gives you the ability to add a wider variety of plants and shrubs to your garden.
Below is a full guide to ericaceous soil, including its benefits, the types of plants that need it, how to grow your own ericaceous soil and frequently asked questions.
What Is Ericaceous Compost?
Ericaceous compost is a type of acidic compost that’s used for growing specific types of plants.
These can include heathers (‘ericaceous’ is derived from the Latin name for heathers), camellias and rhododendrons but it can be used for pretty much any type of plants that don’t do well in alkaline soil.
What Are Its Benefits?
There are some great benefits of using ericaceous soil. These include –
- Great for use with potted plants
- Creates a perfect environment for acid-loving plants to flourish
- Minimal feeding is required when good nutrients are used in the mix
- Retains moisture very well
- Is easy to make yourself
What Plants Need Ericaceous Soil?
There are many types of plants and shrubs that prefer ericaceous soil, including –
- Bilberry
- Heather
- Gardenia
- Trillium
- Lily of the Valley
- Trillium
- Rhododendron
- Japanese Iris
- Hydrangea
- Begonia
See a full list of 76 ericaceous plants in this guide.
When To Avoid It
Although ericaceous compost can be incredibly useful, there are times when it’s better not to use it.
Any plants that prefer alkaline soil, for example, would not be suitable for use with ericaceous compost.
Although ericaceous soil that’s only slightly acidic might not kill these types of plants, they won’t thrive in the same way as they would in alkaline soil.
Use With Potted Plants
Ericaceous compost is excellent for use with potted plants for a few reasons.
Firstly, you can easily maintain the integrity of the compost when it’s not mixed in with other soil, as it might be in a garden bed or border.
Another big advantage to using ericaceous compost for potted plants is that you can grow them in the perfect position for them to thrive.
In most cases, acid-loving plants do best in light shade and kept out of direct sunlight, especially during the peak times of the day.
Watering & Feeding Plants in Ericaceous Soil
Although ericaceous compost typically maintains moisture well, this doesn’t mean you’ll never need to water plants that are in it.
It’s very important to keep the soil moist during dry spells by watering regularly.
It’s also vital to water any ericaceous plants when you’ve first planted them to ensure the bud survives.
When watering plants in ericaceous compost, it’s worth noting that regular tap water is usually alkaline, so using it on them could easily neutralise the soil.
To avoid this, it’s usually best to collect rainwater to use exclusively on ericaceous plants.
As for feeding, it’s always a good idea to use a good fertiliser if you want your plants to thrive.
You can buy plant feed that’s specifically designed for ericaceous plants and it’s certainly recommended you use this since it will contain all the required nutrients for your plants to flower at their best.
A lot of the most popular ericaceous plants flower during spring and summer, so this would be the best time to feed them.
How To Make Ericaceous Compost
Although there are plenty of places you can buy ericaceous compost, it’s quite easy to make it yourself. It mostly comes down to making the soil more acidic than it is alkaline.
To do this you can add things like pine needles, citrus peels and leaf mould to your existing compost mix.
Another way to increase the acidity of a compost mix is by adding sulphur chips to it.1Sellmer, J., PhD. (n.d.). Soil Management in Home Gardens and Landscapes. Penn State Extension. Retrieved March 15, 2023, from https://extension.psu.edu/soil-management-in-home-gardens-and-landscapes
It’s important to note that when you’re making your own ericaceous compost, you won’t be able to add anything that might neutralise the pH of the compost, such as calcium or lime.
You’ll want to regularly test the pH levels of your compost to ensure that the right level of acidity is maintained.
This is particularly important when you’re adding ericaceous compost on top of regular soil since it will lose acidity over time.
Regularly adding new acidifying materials will help to ensure that the soil stays at a very high level of acidity.
It’s also a good idea to add a layer of mulch.
Acidifying Regular Garden Soil
If you want to acidify your existing garden soil rather than making your own ericaceous compost, then this is quite easy to accomplish.
You can simply add sulphur powder to the soil until it reaches the level of acidity you require.
In order to know how much sulphur powder to use, you’ll need to know the current pH level of the soil you’re adding it to.
Because sulphur powder is very fine, you’ll want to add it to your soil when the weather is mild.
It’s also important that you wear the right safety equipment when using sulphur power. You should always wear safety goggles, a dust mask and gloves when you’re applying it.
Testing The pH Level Of Ericaceous Soil
How often you should test the pH level ericaceous compost will depend largely on a where you use it.
If you put the ericaceous compost on top of regular soil, in a flower bed or border, then it can easily lose acidity over time, so you should test the pH of the soil quite regularly so you can add acidifying materials such as pine cones if you need to.
“Using ericaceous compost to amend soil pH is often a losing battle,” says Colin Skelly, a Master Horticulturist.
“If you have neutral soil, it might be beneficial to mulch a plant such as Magnolia, which prefers slightly acidic soil, but an alkaline soil will need considerable and continuous amendments to be added to make a change to soil pH.
“In these conditions, growing ericaceous plants in pots is a far more sensible use of time and resources.”
