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Ericaceous compost for hydrangeas: what to check first

Updated: October 2026

When you search for ericaceous compost for hydrangeas, the bags can look interchangeable: pictures of acid-loving plants, large litre numbers and broadly positive star ratings. They are not equally well specified, and you may not need an acid mix at all. Start with the hydrangea and the flower colour you want, then check explicit peat wording, printed pH and every quantity field before price or reviews. Our [hydrangea soil comparison](/hub/fertiliser-soil-and-bark-mulch/hydrangea-soil) sets out the seven amazon.co.uk listings. This page is the decision order: when a general container mix is enough, and when conflicting litres should make you pause.

When you search for ericaceous compost for hydrangeas, the bags can look interchangeable: pictures of acid-loving plants, large litre numbers and broadly positive star ratings.

Our top picks

SIC SIC Ericaceous 50 L

Best overall

SIC SIC Ericaceous 50 L
9.2/10about £12.49
View offer
Green Haven Green Haven Ericaceous 50 L

Rank 2

Green Haven Green Haven Ericaceous 50 L
9.4/10about £12.49
View offer
ecoblaze TerraGrade Ericaceous 50 L

Best value

ecoblaze TerraGrade Ericaceous 50 L
8.4/10about £9.99
View offer
On this page
  1. 1.When you do not need hydrangea soil
  2. 2.Choose the species and colour before the bag
  3. 3.Check peat wording and printed pH
  4. 4.Read title litres against every other field

When you do not need hydrangea soil

Ericaceous compost is a lime-free specialist medium. It is most relevant when you want a colour-changing mophead or lacecap to stay blue, especially in a container on alkaline ground. White cultivars, panicle hydrangeas and arborescens types such as 'Annabelle' do not turn blue because the bag is acid. Where blue is not the aim, the RHS suggests two parts peat-free John Innes No.3 to one part peat-free multi-purpose compost. Compost tipped into one hole does not permanently change a chalky border. Depth and first-season water are in the guide to planting a hydrangea in compost.

Choose the species and colour before the bag

Mophead and lacecap Hydrangea macrophylla, and some Hydrangea serrata cultivars, can move between blue, mauve and pink. The RHS associates blue with acid soil around pH 4.5 to 5, where aluminium is available. Read the plant label before the compost label. Paniculata, arborescens or a white cultivar is not a reason to buy an acid bag for a colour change. A blue-capable mophead on limestone or chalk belongs in a pot. A hydrangea name on a listing is suitability wording, not a pH: the Laeto sizes name hydrangea and state neither a number nor peat-free status, while SIC states pH 4.0 and peat-free without naming hydrangeas. Colour limits are in how to keep hydrangeas blue.
SIC SIC Ericaceous 50 L

Testsieger

SIC SIC Ericaceous 50 L
9.2/10about £12.49
View offer

Check peat wording and printed pH

If avoiding peat matters, look for the words peat-free. The RHS warns that a product which does not say peat-free most likely is not. Eco, natural and organic do not answer the same question. SIC states peat-free in the title and bullets. The indigo item-type field says peat free compost. TerraGrade, Green Haven and the Laeto listings do not. Peat-free status and acidity are separate checks. SIC is the only listing here that prints a number, pH 4.0. TerraGrade claims a low pH, Green Haven claims slow-release iron, and indigo claims six months of feed. Do not turn a feed or iron line into a measured acidity. TerraGrade is £9.99 and SIC is £12.49, so the lower price is the bag with less specification. indigo is £14.99, with peat-free item-type wording and only three ratings. Which listing fits which job is in best ericaceous compost.

Read title litres against every other field

Do not plan a job from the title alone. All seven listings disagree with themselves. TerraGrade says 50 L in the title and 44 litres in the volume field. SIC and Green Haven each say 50 L beside 60 litres. indigo says 46 L and 50 litres. Laeto's 20, 50 and 100 L titles sit beside 10, 20 and 40 litre fields. Listed weights, from 3 kg to 14.9 kg, do not settle the clash, because compost density changes with moisture. Keep the order record and check the bag on arrival. Price per title litre is only a label: about 20p for TerraGrade, about 25p for SIC and Green Haven, and about 58p for the Laeto 20 L title. None of those rates confirms the fill.

Common questions

Do all hydrangeas need ericaceous compost?
No. It is most useful for maintaining blue colour in responsive mophead, lacecap and some serrata hydrangeas, especially in pots on alkaline ground. White, panicle and arborescens types do not become blue in acid compost. For a container where blue is not the goal, a loam-based John Innes and peat-free multi-purpose mix may be more appropriate.
How can I tell whether a bag is peat-free?
Look for an explicit peat-free statement on the bag or listing. Do not infer it from organic, eco or green packaging. In this seven-product comparison, SIC makes a clear peat-free claim and indigo uses peat-free wording in the item-type field. The other listings do not state it.
Is pH 4.0 too acidic for a hydrangea?
SIC's listing states pH 4.0, while the RHS associates blue hydrangea flowers with acid conditions around pH 4.5 to 5. A printed bag figure is useful for comparison, but it is not a test of the compost you receive or a guarantee of flower colour. The pot's pH can also change with watering and time.
Is a 20 L bag enough for one pot?
It may be, but the answer depends on the pot's internal shape, the volume of the existing rootball and how much headspace you leave. The Laeto 20 L title in this comparison also conflicts with a 10 litre field, so do not promise a complete repot from its title alone.
Should star ratings decide between two bags?
Use them last. Ratings can reveal broad customer experience, but they do not resolve peat wording, pH or volume conflicts. Laeto's three sizes share one 4.6-from-656 line, while indigo's 4.6 rests on only three reviews. Match the specification first, then read recent feedback for recurring delivery or texture issues.
What if I want pink flowers?
Do not buy ericaceous compost solely because the plant is a hydrangea. Responsive cultivars tend towards pink in alkaline conditions, while non-responsive plants retain their genetic colour. Choose an appropriate general container mix and care for the shrub. Changing soil chemistry without a reason can complicate neighbouring plants and feeding.

Related pages

Hydrangea soil for pots

Hydrangea soil

Best ericaceous compost for the hydrangea job in hand

How to keep hydrangeas blue with soil, pH and water

How to plant a hydrangea in compost: depth and water

Sources

Public UK sources checked for this page in October 2026. Prices, stars and review counts are from the seven amazon.co.uk listings on file. A peat-free line, a pH and a feed period are listing claims. Title litres are not treated as the fill when the volume field disagrees. This is not a laboratory test. A 2022 Defra announcement is not a ban already in force.

  1. RHS, how to grow shrubby hydrangeas (retrieved 23 October 2026)
  2. RHS, acidifying soil (retrieved 23 October 2026)
  3. RHS, peat-free compost (retrieved 23 October 2026)
  4. Gardeners' World, ericaceous compost (retrieved 23 October 2026)
  5. Gardeners' World, how to grow hydrangeas (retrieved 23 October 2026)
  6. Defra, sale of horticultural peat to be banned (retrieved 23 October 2026)
  7. Peat Free Partnership, legislation timeline (retrieved 23 October 2026)
  8. Consumer Rights Act 2015, section 11 (retrieved 23 October 2026)