The best rhododendron fertilisers, compared.
Top pick: Miracle-Gro granule and liquid bundle Best value: Westland ericaceous liquid 2 litres – Two litres of ericaceous liquid at about £14.00, with 4.6 from 594 reviews, the strongest listed liquid quantity for the money in this set. Updated October 2026.
A rhododendron fertiliser is plant food for rhododendrons and other acid-loving shrubs, including azaleas, camellias, heathers and blueberries. In the UK you buy one for a pot, for a tired shrub, or when leaves yellow because the soil is not acid enough. The Royal Horticultural Society puts rhododendrons near pH 5.0 to 6.0. A shrub already growing in decent acid soil often needs no extra feed. On chalk, a bag does not replace a pot or a raised bed of ericaceous compost. A suitable pack matches the job. A once-a-spring granule, a liquid you dilute through the growing season, and an iron or magnesium tonic are different products. Read nitrogen, phosphate and potash in UK oxide order, and check whether iron is declared. Use the printed grammes and the month on the label. Skip a general feed after midsummer if you want next year's flowers. Granules belong over the outer roots, not against the stem. The [rhododendron fertiliser buying guide](/hub/fertiliser-soil-and-bark-mulch/rhododendron-fertiliser/sub/rhododendron-fertiliser-buying-guide) sets out how to read a declaration before you choose a tub.
A rhododendron fertiliser is plant food for rhododendrons and other acid-loving shrubs, including azaleas, camellias, heathers and blueberries.
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Personal buying guide
Question 1 of 2
How do you want to feed?
This listing combines continuous-release granules with concentrated liquid, so it covers both a spring application and later measured feeding. The listed price is £15.85, but the pack data only clearly accounts for 800 ml and does not state the number of packs. A 5.0-star average is based on only six ratings and is not stronger evidence than hundreds of ratings. The bundle can be useful if you deliberately want both formats. It also makes overlapping feeds easier to get wrong. There is no review narrative here that resolves the incomplete pack description.
Pros
Cons
Best for: Gardeners who specifically want both a spring granule and a separate liquid.
Less suitable: Anyone who wants a simple one-product schedule or a large review sample.
Specifications
Common questions
What is in the bundle?
A continuous-release granule and the concentrated liquid, model 121180. The listing also names flowers, vegetables, trees and shrubs alongside azaleas, camellias and rhododendrons.
How should the two feeds be used?
The listing claims one application at the start of spring for the granule. Adding the liquid on top of that dose is a second feed. Keep the two schedules from stacking.
What size and price are on the listing?
About £15.85. The pack line shows 0.8 litres and does not state how many packs. amazon.co.uk shows 5.0 from 6 reviews.
This listing presents Vitax rhododendron feed as two resealable 0.9 kg pouches for £15.43. The product type is relevant, and the listed price is lower than the other Vitax twin-pouch listing. Its 5.0-star average is based on only two ratings, so it is not evidence of superiority. The listing also conflicts with itself by stating two packs while showing a 900 g unit count. With no application rate on the listing, confidence in what will arrive and how to use it is limited. The pouch-line analysis, 9:7.5:10.2 with 1.0% iron, belongs to this Vitax feed, but you still need the label in the box for the dose.
Pros
Cons
Best for: A repeat buyer who already knows the Vitax pouch and can check the twin-pack contents.
Less suitable: A first purchase that relies on the star line or on precise pack information.
Specifications
Common questions
How many reviews does this listing have?
Two. The average is 5.0. That sample is too small to treat as stronger evidence than a 4.6 from hundreds of reviews.
Do the pack figures agree?
No. The title says two 0.9 kg pouches. The unit count shows 900 g. Check the contents before you rely on the title.
What price is listed?
About £15.43. The listing does not state an application rate.
This twin pack provides 1.6 litres of concentrated liquid feed for £14.20. Its 4.6-star rating from 1,315 reviews is the largest sample in the comparison, but rating volume alone does not establish how well it suits rhododendrons. The model number 121180 corresponds to an ericaceous liquid, and the brand page lists that liquid as 7-3-5, while the bullets refer to flowers, vegetables, trees and shrubs. You must dilute it before use, yet the listing does not provide a mixing ratio. That mismatch makes it a plausible repeat-feed option, and a less clear purchase than a listing whose plant scope and directions agree.
Pros
Cons
Best for: Readers who recognise model 121180 and want a twin pack for a regular liquid-feeding routine.
Less suitable: Anyone wanting unambiguous directions or a single spring application.
Specifications
Common questions
Which plants do the bullets name?
Flowers, vegetables, trees and shrubs. The model number is 121180, which the brand sells as an azalea, camellia and rhododendron liquid. Do not treat the vegetable bullet as the specialist analysis.
What analysis applies to model 121180?
The brand page lists NPK 7-3-5. The amazon listing in this set does not print a mixing ratio.
What size and price are on the listing?
About £14.20 for two 800 ml bottles, 1.6 litres in total. amazon.co.uk shows 4.6 from 1,315 reviews.
This 900 g granular feed is the clearest one-application option in the set, with the listing saying that a spring application feeds for the season. Its £8.10 listed price and 4.6-star rating from 785 reviews give it a stronger evidence base than most alternatives here. It is specifically named for azaleas, camellias and rhododendrons rather than for a broad mix of plants. The controlled-release claim is useful if you do not want to measure liquid feed every fortnight, although it remains a manufacturer claim rather than an independent trial result. The label's high-nitrogen analysis and serious eye-hazard warning mean careful measuring and handling still matter. It is the top pick for one measured spring feed.
Pros
Cons
Best for: Established acid-loving shrubs when you want one measured spring feed.
Less suitable: Gardeners who prefer adjustable liquid feeding or need to diagnose yellow leaves before feeding.
Specifications
Common questions
Which plants does this listing name?
Azaleas, camellias and rhododendrons. The brand on the listing is Miracle-Gro.
How does the listing say you apply it?
One application at the start of spring. The label doses are 15–20 g for a new plant, 30–60 g for an established shrub and 15–30 g in a container. The season-long claim is the maker's statement.
What size and price are on the listing?
About £8.10 for 900 g. amazon.co.uk shows 4.6 from 785 reviews. The label warns of serious eye damage.
This Westland twin pack provides two litres of liquid feed described for ericaceous plants, including rhododendrons, azaleas, camellias and blueberries. At the listed £14.00 price, it offers the strongest stated liquid quantity for the money in this comparison. The 4.6-star average from 594 reviews is a substantial sample, although those ratings are not a controlled product test. It suits pots and gardeners who will dilute feed on a schedule rather than rely on one spring dose. The listing omits the mixing ratio. The brand rate is 50 ml in 4.5 litres, every one to two weeks from March to September, kept off the foliage, so use the bottle you receive rather than another brand's ratio. It is the best value in this set.
Pros
Cons
Best for: Rhododendrons in pots, and gardeners who already follow a liquid-feeding routine.
Less suitable: Anyone wanting a single spring application with no repeated dilution.
Specifications
Common questions
Which plants does this listing name?
Ericaceous plants, including rhododendrons and azaleas as well as camellias and blueberries. The brand is Westland.
How do you dilute it?
The listing says dilute before use and does not print a ratio. The brand rate is 50 ml in 4.5 litres, every one to two weeks from March to September, kept off the foliage.
What size and price are on the listing?
About £14.00 for two 1 litre bottles. amazon.co.uk shows 4.6 from 594 reviews.
This Vitax twin pouch is a granular feed for ericaceous plants, with an organic-based formula and added iron stated on the listing. Its 4.6-star average from 242 ratings is a useful, smaller evidence base than the leading listings. The listed £17.48 price is for a pack described as two 0.9 kg pouches, but the weight fields disagree, showing 998 g alongside a 1,800 g unit count. The Vitax pouch line declares 9:7.5:10.2 with 1.0% iron, which is a more moderate nitrogen balance than the high-nitrogen controlled-release granule. The listing does not state the application rate. The pouch label prints 30 g per square metre in March or April and again at first flowering, or 40 g if the leaves are yellow.
Pros
Cons
Best for: Gardeners who want an iron-containing granular ericaceous feed and will follow the pouch label.
Less suitable: Buyers who need consistent pack data or the lowest upfront price.
Specifications
Common questions
Which plants does this listing name?
The title and bullets say ericaceous plants. One listing field names blueberries and raspberries. Use the pouch label as the plant list that counts.
How much does the pouch label say to use?
The amazon listing does not state a rate. The pouch label prints 30 g per square metre in March or April and again at first flowering, or 40 g if the leaves are yellow.
What size and price are on the listing?
About £17.48. The title says two 0.9 kg pouches, while the weight fields show 998 g and a 1,800 g unit count. amazon.co.uk shows 4.6 from 242 reviews.
This £15.25 bundle pairs a rhododendron continuous-release granule with a separate rose and shrub feed. The first component is relevant to azaleas, camellias and rhododendrons. The second is not interchangeable with it. Its 4.6-star average is based on only 12 ratings, which is limited next to the standalone 900 g granule. The fields say one pack of 900 g while the unit count indicates 1,800 g, so check the bundle at purchase. It makes sense only if you grow both and keep the application schedules separate. Do not put the rose tub on the rhododendron.
Pros
Cons
Best for: A garden with both acid-loving shrubs and roses, and two separate feeding plans.
Less suitable: Anyone shopping only for rhododendron feed, or anyone who wants consistent pack data.
Specifications
Common questions
Can both tubs go on a rhododendron?
No. One tub is the rhododendron feed. The other is rose and shrub feed. Do not put the rose tub on the rhododendron.
What does the listing claim about timing?
One application at the start of spring is claimed for the rhododendron component. That is a listing claim, not an independent trial.
What size and price are on the listing?
About £15.25. The fields say one pack and 900 g, while the unit count says 1,800 g. amazon.co.uk shows 4.6 from 12 reviews.
Substral Thuja-Vital is a 500 ml liquid positioned for Thuja and other evergreen woody plants rather than specifically for rhododendrons. The directions distinguish watering as prevention from spraying as immediate help, and the listing supplies a ratio for each method. Its 4.5-star average comes from 274 ratings, but it is weak evidence for a rhododendron. At £22.80 it is an expensive liquid for the smallest stated volume here. The same product line is described as Mg-S 5-10 with chelated iron, not as a season-long NPK feed. It makes more sense as a specialist evergreen tonic than as a default ericaceous feed.
Pros
Cons
Best for: A Thuja or evergreen job where you need the stated watering or spray ratio.
Less suitable: A routine rhododendron feed, or a purchase led by price.
Specifications
Common questions
Is this a rhododendron fertiliser?
The listing names Thuja. The wider evergreen line includes rhododendron among other woody plants. It is described as Mg-S 5-10 with chelated iron, not a full NPK feed for the season.
What ratios does the listing give?
1:80 for watering, described as prevention, and 1:67 for spraying, described as immediate help. Those are listing claims.
What size and price are on the listing?
About £22.80 for 500 ml. amazon.co.uk shows 4.5 from 274 reviews.
This one-litre Miracle-Gro liquid is explicitly named for azaleas, camellias and rhododendrons and cost £8.99. It is a smaller bottle than the twin packs if you want less product to store. Its 4.5-star average is based on only 16 ratings, so the evidence is much thinner than for the larger Miracle-Gro and Westland listings. The listing states neither a nutrient analysis nor a mixing ratio. It may suit a limited number of pots, but you need the bottle instructions before you measure a dose. Do not copy an NPK figure from a different Miracle-Gro liquid onto this model.
Pros
Cons
Best for: A small collection of acid-loving plants when you want a one-litre liquid.
Less suitable: Buyers who want a documented dose or a large review sample.
Specifications
Common questions
Which plants does this listing name?
Azaleas, camellias and rhododendrons. The model number on the listing is 531660.
What is the nutrient analysis?
The listing does not state one. Do not borrow the 7-3-5 figure from model 121180 or the 20-7-16 figure from the granules.
What size and price are on the listing?
About £8.99 for 1 litre. amazon.co.uk shows 4.5 from 16 reviews. No mixing ratio is printed.
This 1.5 kg sulphate of iron product is an iron salt rather than a complete seasonal rhododendron food. It may have a role when iron or soil acidity is the identified issue. It is not the automatic answer to every yellow leaf. The 4.4-star average comes from 64 ratings, and the listing ranks the product under moss control rather than flower fertilisers. At £24.14 it is the most expensive product in the comparison. The listing gives no application rate. Using it without a diagnosis and the current label is a poor substitute for a balanced feed. Iron solution can stain paving.
Pros
Cons
Best for: A specific iron or acidifying task, using the current label after you have identified the problem.
Less suitable: Routine feeding, or unexplained yellowing before drainage, roots and pH have been checked.
Specifications
Common questions
Is this a complete rhododendron fertiliser?
No. It is sulphate of iron, an iron salt. It does not replace nitrogen, phosphate and potash for the season.
Where does the listing rank it?
Under moss control, not under flower fertilisers. amazon.co.uk shows 4.4 from 64 reviews.
What size and price are on the listing?
About £24.14 for 1.5 kg. No application rate is printed. Iron solution can stain paving.
Ten amazon.co.uk listings were scored from the stored pages dated 21 October 2026. There is no laboratory test. A season-long claim, a dilution line or a plant list is the seller's or the maker's statement. Where two figures on one listing disagree, both stay and the clash is a deduction. A 5.0 from two or six ratings does not outweigh a 4.6 from several hundred. The highest score is the top pick. The best value is the strongest listed liquid quantity for the money among feeds aimed at ericaceous plants. The weights below sum to 100.
Amazon rating and sample size
35%The star average is read together with the number of ratings. Very small samples take a substantial confidence cut. Hundreds of ratings outweigh a 5.0 from two or six ratings. Stars are not a laboratory test.
Fit for the job
30%Preference goes to products clearly labelled for rhododendrons or ericaceous plants, with a complete feed and application information where the listing has it. An iron salt or a Thuja liquid is a different job and scores lower on this block.
Value
20%The listed price in GBP is judged against the stated amount, the format and the job. This is not a cheapest-price guarantee. The £22.80 and £24.14 packs are a conifer tonic and an iron bag, not a fuller NPK food.
Listing clarity
15%Consistent pack quantities, clear directions and a coherent plant scope score higher than incomplete or conflicting fields. Generic bullets that describe a specialist bottle as food for vegetables are a deduction.
Match the job before the star line. A spring granule, a diluted liquid and an iron tonic are not one list. Prices below are amazon.co.uk shelf prices on 21 October 2026. This is not a laboratory test.
A rhododendron fertiliser is plant food for rhododendrons and other acid-loving shrubs, usually azaleas, camellias, heathers and blueberries. Quality is the match between the job and the declaration: a once-a-spring granule, a diluted liquid used through the growing season, or an iron or magnesium tonic that is not a full NPK feed. Prices, stars and review counts here are from the amazon.co.uk listings dated 21 October 2026. This is not a laboratory test. Start with the soil or the compost.
Decent acid soil often carries an established rhododendron without a bag. Extra nitrogen after midsummer pushes soft growth when you want next year's flowers.
Sulphate of iron and an evergreen tonic are not a season NPK feed. Doubling a dose because the leaves are yellow can scorch tips. Check pH, drought and roots first.
One bundle includes a rose and shrub feed beside the rhododendron granule. The rose tub is a different product. Granules belong over the outer roots, not against the stem.
The Royal Horticultural Society puts rhododendrons near pH 5.0 to 6.0 and says a shrub in decent acid soil often needs no extra feed. On chalk, use a pot or a raised bed of ericaceous compost before you buy a bag. Read nitrogen, phosphate and potash in the order N, P2O5, K2O, and check whether iron is declared. The 900 g granule is about 20-7-16 with 0.18% iron. The Vitax pouch line is 9:7.5:10.2 with 1.0% iron. Higher nitrogen is not a better score. Label grammes beat a handful.
A once-a-spring granule, a diluted liquid, sulphate of iron and an evergreen anti-brown liquid are different jobs. A mycorrhizal inoculant is not this category. One bundle adds rose food. Do not put that tub on the rhododendron. Another bundle pairs granules with liquid and makes a double dose easy. Several listings disagree with themselves on weight. A 5.0 from two or six reviews is a thinner file than 4.6 from several hundred. Stars are not a laboratory test.
Three typical situations, each with a recommendation from this comparison.
You need either a spring granule or a summer liquid, rainwater if the tap is hard, and a repot every other year. For a regular liquid routine the best value is Westland ericaceous liquid, two litres at about £14.00, with 4.6 from 594 reviews. The brand rate is 50 ml in 4.5 litres. The listing itself does not print that ratio, so follow the bottle.
A shrub growing in decent acid soil often needs no bag at all. If growth is tired and the pH is already in range, one measured spring dose is the simpler job. Miracle-Gro continuous release 900 g is about £8.10, with 4.6 from 785 reviews. Skip a heavy nitrogen dose after midsummer if you want next year's flowers.
Yellow leaves are a pH decision before they are a tub. On chalk, feed does not replace ericaceous compost in a pot or a raised bed. If the compost is already suitable and you want iron inside a complete feed, the Vitax pouch declares 1.0% iron, at about £17.48 with 4.6 from 242 reviews. Sulphate of iron is not that feed, and it will not turn chalk into acid soil.
The top pick is Miracle-Gro continuous release granules, 900 g, at about £8.10. The listing names azaleas, camellias and rhododendrons, claims one application at the start of spring, and amazon.co.uk shows 4.6 from 785 reviews. The label is about 20-7-16 with 0.18% iron and warns of serious eye damage. The best value is Westland ericaceous liquid, two litres at about £14.00, with 4.6 from 594 reviews. Use the bottle ratio, because the listing does not print one. Sulphate of iron and Thuja-Vital are not full NPK feeds. A rose tub in a bundle does not belong on the rhododendron. None of these scores is a laboratory test.
Westland ericaceous liquid 2 litres
Two litres of ericaceous liquid at about £14.00, with 4.6 from 594 reviews, the strongest listed liquid quantity for the money in this set.
Editorial
Peter F. is the editor for DIY & tools at productscompared.co.uk. Comparisons in this category are checked against amazon.co.uk listings, review evidence and public UK sources.
Guides on what to look for, how to use a product, and common mistakes.
Public UK and maker sources from the research digest, used for this page in October 2026. Prices, stars and review counts are from the ten amazon.co.uk listings dated 21 October 2026. A season-long claim is the maker's statement. The 900 g label warns of serious eye damage. No pack here is described as pet-safe.
Expert source (DIY & tools): Lee Burkhill (Garden Ninja) (external profile) – public expert commentary used as a research source, not as a contributor to our pages.
This page contains affiliate links to amazon.co.uk (tag pcuk26-21). If you buy through them, we may earn a commission at no extra cost to you. Prices, stars and review counts are from the listings. This is not a laboratory test.
