🎧 Listen to this article (narrated by Daniel):
Walk into any garden centre and the compost aisle can stop you in your tracks. Dozens of bags, all claiming to be the best. At Cedar Nursery, we hear the same question week after week: "Which one should I actually buy?" The honest answer is that it depends on what you are planting - but knowing your top 3 composts makes the decision straightforward every time.
Not all compost is created equal
Compost is not a generic product. Different formulas are built for different jobs, and using the wrong one is one of the most common reasons plants struggle in their first season. A rhododendron planted into alkaline compost will turn yellow and sulk. A tree planted with standard container mix may establish slowly, lacking the structure its roots need. The right compost does the work for you. The wrong one quietly works against you.
You do not need to memorise every product on the market. You need to know three. Here they are.
1. Multi-Purpose Compost with John Innes - the one bag that does it all
This is the compost we reach for most often when customers are filling containers, patio pots, or hanging baskets. It is a blend of a general multi-purpose mix with a loam-based John Innes element - and that combination makes a real difference.
Standard multi-purpose compost is light and open when you first use it, but in a large container it can compact and dry out surprisingly quickly. The John Innes component adds weight, structure, and improved water retention. It holds moisture more evenly, which means less frantic watering in summer and fewer plants lost to dry spells.
Best used for:
- Pots and containers of all sizes
- Patio displays and seasonal plantings
- Hanging baskets and window boxes
- General container planting where you want reliable results without fuss
Why we recommend it: Think of it as the smart upgrade from plain multi-purpose. Experienced gardeners tend to use this as their default container compost because it performs consistently across a wide range of plants. You do not need to mix anything - it comes ready to use, straight from the bag.
Common mistake to avoid: Using standard multi-purpose in large containers. Without the loam structure, it compacts over time, drainage suffers, and roots struggle. The John Innes blend solves this problem before it starts.
2. Ericaceous Compost - essential for acid-loving plants
Some plants are particular about their soil chemistry, and that is not a problem - it just means using the right compost. Ericaceous compost is specifically formulated for plants that need acidic conditions to thrive. It contains no lime or chalk, which gives acid-loving roots exactly the environment they require.
Best used for:
- Rhododendrons
- Camellias
- Blueberries
- Azaleas
- Pieris
Why we recommend it: For these plants, ericaceous compost is not optional - it is non-negotiable. When acid-loving plants are grown in neutral or alkaline compost, they cannot absorb iron and other nutrients properly. The result is chlorosis: leaves turn yellow between the veins, growth slows, and the plant looks permanently unhappy. Switch to ericaceous compost and the difference is striking. We see it every season.
If your garden soil is naturally alkaline - as much of Surrey's chalk and clay ground can be - growing these plants in containers with ericaceous compost is often the most practical solution.
Common mistake to avoid: Assuming a standard compost will do for acid-lovers because "it's still compost." It will not. The pH difference is the whole point.
3. Specialist Tree, Shrub, and Rose Compost - for plantings that are meant to last
When you are planting something permanent - a tree, a mature shrub, a climbing rose - the compost you use at planting time has a long-lasting effect on how well it establishes. This is the moment to use a specialist planting compost formulated for open-ground use.
These composts are richer in nutrients and structured differently from container mixes. They are designed to support strong root development through the first season and beyond, helping new plantings withstand their first summer drought or winter freeze.
Best used for:
- Trees and specimen shrubs planted in open ground
- Roses - both new plantings and established ones being refreshed
- Hedging plants being established in a new run
- Any long-term planting where establishment matters
Why we recommend it: When a customer buys a mature specimen tree from us - something that has taken years to grow - we always talk about what goes into the planting hole. A specialist compost is a modest investment relative to the cost of the plant itself, and it genuinely improves the odds of strong establishment. This is not the place to use up leftover bags of general compost.
Common mistake to avoid: Using standard multi-purpose for in-ground planting of trees and shrubs. It lacks the nutrient depth and structural qualities that long-term plantings need. It is designed for containers, not for supporting a tree through its first decade.
Quick reference guide
| Plant type / situation | Recommended compost |
|---|---|
| Pots, containers, patio displays | Multi-Purpose with John Innes |
| Rhododendrons, camellias, blueberries, azaleas | Ericaceous compost |
| Trees, shrubs, roses in open ground | Specialist tree and shrub compost |
Frequently asked questions
What is the difference between multi-purpose and John Innes compost?
Multi-purpose compost is a general-purpose blend, typically based on composted bark or coir. John Innes compost is loam-based - it contains sterilised soil, which gives it better structure, weight, and water retention. For containers, a blend of both gives you the best of both worlds: the lightness and nutrients of multi-purpose, with the stability of loam. That is why multi-purpose with John Innes is our go-to recommendation for pots.
Can I use multi-purpose compost for acid-loving plants?
No - and this is one of the most common mistakes we see. Standard multi-purpose compost is typically neutral to slightly alkaline in pH. Acid-loving plants like rhododendrons, blueberries, and camellias need an acidic environment to absorb nutrients properly. Planting them in the wrong compost leads to chlorosis - yellowing leaves and poor growth. Ericaceous compost is the correct choice, and there is no substitute.
What compost should I use when planting a tree or shrub in the garden?
Open-ground planting calls for a specialist compost designed to support root establishment over the long term. Standard container compost lacks the structure and nutrient depth that trees and shrubs need once they are in the ground. A tree and shrub planting compost is formulated specifically for this job - and when you are investing in a mature specimen, it is worth getting this right from the start.
Is peat-free compost as good as peat-based?
Peat-free quality has improved significantly in recent years, and there are genuinely excellent peat-free options available. At Cedar Nursery, we stock quality peat-free composts and recommend them with confidence. Some gardeners find they need to adjust their watering habits slightly - peat-free mixes can behave a little differently when dry - but for most applications the results are comparable. It is the right direction for horticulture, and the products have caught up.
How much compost do I need for a large container?
A rough guide: measure the volume of your container in litres (length x width x depth in centimetres, divided by 1,000). Fill to about 80% capacity to leave room for watering. A 60-litre planter needs roughly 50 litres of compost. For very large planters - anything over 100 litres - it is worth mixing in some horticultural grit to improve drainage and reduce the overall weight if the container is on a roof terrace or balcony.
Still not sure? Ask us.
Choosing the right compost is the single most impactful thing you can do before a plant goes into the ground. It costs very little relative to the plants themselves, but it makes a genuine difference to how well they establish and perform.
At Cedar Nursery, we have been helping gardeners get this right since 1986. Our team works with plants every day - we know what works in Surrey soils and what does not. If you are not sure which compost suits your project, come and talk to us in the nursery in Cobham, less than 5 miles from RHS Wisley. We will give you a straight answer, not a sales pitch.
You can also browse our plant and compost range at landscaping.co.uk before you visit. Cedar Nursery is at Horsley Road, Cobham, Surrey, KT11 3JX - open Monday to Saturday, 8:30am to 5pm. Call us on 01932 862473 or visit landscaping.co.uk. Free local delivery is available on orders over £100 within Surrey, the Home Counties, and parts of Greater London.