The best slow release fertilisers, compared.
Top pick: Miracle-Gro Slow Continuous Release, 6 × 1 kg Best value: Doff Multipurpose Controlled Release Fertiliser 1 kg – Printed NPK 10:5:11 on a 1 kg shaker at about £8.38. The file is 4.4 from 24 reviews, and a plug-plant burn report stays on the page. Updated October 2026.
A slow release fertiliser is a garden granule you work into compost or sprinkle on soil so plants take up nutrients over a stated number of months. In the UK you buy it in spring for hanging baskets, borders and patio pots, often after the short feed already in peat-free compost has run out. A pack that tells you to reapply every four to six weeks is a different product. A suitable bag prints a month window, a nutrient declaration under the Fertilisers Regulations 1991, and a rate in grams. Match the plant group. Mixed beds take an all-purpose granule. Camellia, blueberry and rhododendron need an ericaceous granule. A rose, tree and shrub title should name those plants. Water the granules in, keep them off stems, and do not spread them on frozen or waterlogged soil or near a pond or a drain. A blend with a fast fraction can burn young plants if you exceed the rate. How to match the month claim to the plant group is set out in the [slow release fertiliser buying guide](/hub/fertiliser-soil-and-bark-mulch/slow-release-fertiliser/sub/slow-release-fertiliser-buying-guide).
A slow release fertiliser is a garden granule you work into compost or sprinkle on soil so plants take up nutrients over a stated number of months.
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Personal buying guide
Question 1 of 2
What are you feeding?
The Miracle-Gro listing is a case of six 1 kg continuous-release shaker jars at about £44.90. The unit count is 6,000 g and the item-weight field is 1 kg. amazon.co.uk shows 4.6 from 46 reviews, a thin written sample. That is the highest star line here. It is not a laboratory win, and it is not the top pick. Reviewers call it easy to sprinkle on the garden. One said it rescued dying plants. The listing has almost no bullets beyond the title, and it prints neither an NPK nor a month window. One review said a well-wrapped packet contained only five jars. Buy the case only if you will use six jars. It is not the common single jar of about 900 g.
Pros
Cons
Best for: Many baskets or a large border when you want six named shaker jars and will read the analysis on the jar itself.
Less suitable: A few pots, anyone who wanted a single small jar, or a listing that prints NPK and months on the amazon card.
Specifications
Common questions
How many jars are in this listing?
The title is six 1 kg shaker jars. The unit count is 6,000 g. The item-weight field is 1 kg. One review said the packet contained only five jars.
Does the listing print an NPK or a six-month line?
No. The amazon card prints neither an NPK nor a month window. The title says Slow Continuous Release.
What form is the product?
The item-form field is granules, sold as shaker jars.
Westland Ericaceous Plant Food Granules, 900 g, are an ericaceous slow-release granule at about £6.00 with a three-month claim and a high-potassium bullet. The item-weight field is 770 g. amazon.co.uk shows 4.5 from 282 reviews. Reviewers use it on azalea, rhododendron, camellia, blueberry, holly, skimmia, hydrangea and heather. Several report greener foliage and recovery from yellow leaf. A pairing bullet names a separate Westland ericaceous liquid, sold separately. Against those recoveries sit plant-kill reports: three dead blueberry bushes, granules that turned to mush, and one buyer who said the granules dissolved immediately and killed every acid-loving plant. Surface granules were compared to bird food. It is the specialist acid jar here, not a six-month all-purpose substitute.
Pros
Cons
Best for: Acid-loving plants in ericaceous compost when you will feed again around the three-month window.
Less suitable: Neutral-soil mixed borders, a one-shot six-month all-purpose feed, or anyone who needed a printed NPK on the card.
Specifications
Common questions
How long does the ericaceous jar claim to feed?
A bullet says a 3 month slow release feed. Plan a second application around that window if the plants are still growing.
What plants is it for?
The coverage field is ericaceous plants. The target-species field is rhododendrons. A pairing bullet names a separate Westland ericaceous liquid, sold separately.
What pack size is printed?
The title and the unit count are 900 g. The item-weight field is 770 g. Both figures are copied as printed.
Westland Boost Slow Release Plant Food 2 kg is a slow-release granular plant food at about £11.64. A bullet claims a six-month nutrient supply, and the listing spells that line 6-moth. amazon.co.uk shows 4.5 from 181 reviews. That star line is scaled for the table. It is not a laboratory ranking. Reviewers use it on begonias, roses, hanging baskets, troughs and raised vegetable beds, and several treat one spring application as enough for the summer. A measuring spoon comes up in those texts even though the listing does not name one as included. The recurring complaint is a brittle plastic tub that arrives split, with granules loose in the outer bag. A few spring reviews say it is too early to judge, and one pack was described as mouldy. It is the top pick here for a 2 kg all-purpose six-month granule when you will water it in and can accept a tub that sometimes cracks in transit.
Pros
Cons
Best for: Mixed baskets, beds and troughs when you want one six-month all-purpose charge in a 2 kg tub.
Less suitable: Acid-loving plants that need the ericaceous jar, or anyone who will not accept a tub that sometimes splits in transit.
Specifications
Common questions
How long does the listing say Westland Boost feeds?
A bullet claims a six-month nutrient supply. The listing spells that line 6-moth.
What size is the pack?
The title and the item weight are 2 kg. The unit count is 2,000 g.
Does the listing print an NPK?
No. The amazon listing does not print an NPK. The maker page lists 17.8-7-15.5, and that figure is not on this card.
Goulding G60114 Slow Release Fertiliser, 720 g, is a general-purpose slow-release granule at about £9.39. The item-weight field is 750 g, and a bullet says it lasts up to six months. amazon.co.uk shows 4.4 from 281 reviews. Repeat buyers say plants flourish and name wisteria, roses, agapanthus and dianthus. Some treat it as a season-long feed and skip a mid-season liquid. Humics are named in the bullets. The listing does not print an NPK. One shopper who also bought the rose, tree and shrub sibling said both jars printed the same contents list. Another saw no difference and added fish, blood and bone plus tomato feed. A third said it was no good on strawberries. One review says the packaging had no instructions.
Pros
Cons
Best for: A small general-purpose jar for flowers and shrubs when you want a 720 g season-long sprinkle.
Less suitable: Anyone who needed a printed NPK, a 2 kg bed tub, or a confirmed chemical difference from the rose, tree and shrub Goulding.
Specifications
Common questions
How long does G60114 claim to last?
A bullet says it lasts up to 6 months.
What pack size is printed?
The title and the unit count are 720 g. The item-weight field is 750 g. Both figures are copied as printed.
Is an NPK printed on the listing?
No. The amazon listing does not print an NPK.
Goulding G60115 Rose, Tree & Shrub, 720 g, is titled for rose, tree and shrub at about £9.37. The item-weight field is 750 g, and a bullet says it lasts up to six months. amazon.co.uk shows 4.4 from 143 reviews. Reviewers call it easy to apply and store. One buyer used it on ericaceous plants, though the title is not an acid-feed claim. The listing mixing-ratio field is 1:0:0, which is not an NPK. A shopper who also bought G60114 said both jars had the same contents list. Other notes split between plants doing well and a reviewer who said it does not really do what it says. Visible results are described as slow in one text, which matches a slow-release warning in that review.
Pros
Cons
Best for: A 720 g rose, tree and shrub title when you already accept it may match the general-purpose sibling.
Less suitable: Acid-loving plants, anyone who needed a printed analysis, or a confirmed different formula from G60114.
Specifications
Common questions
What plants is G60115 titled for?
The title and the target-species field are rose, tree and shrub.
What does the mixing-ratio field say?
The listing mixing-ratio field is 1:0:0. That field is not treated as an NPK.
How long does it claim to last?
A bullet says it lasts up to 6 months.
Doff Multipurpose Controlled Release Fertiliser 1 kg is a shaker of controlled-release granules at about £8.38, and the only listing here that prints NPK 10:5:11. amazon.co.uk shows 4.4 from 24 reviews, a thin sample. Short reviews say hanging baskets and pots did well and mention the price. An experienced gardener reported burnt roots on plug plants in hanging-basket work and said the Doff label mentions burning leaves. There is no six-month line. Bullets say plants receive nutrients when they require them, and the listing has no grams-per-pot rate. The best-value badge is the printed analysis and the shaker price, not a claim that the granules never burn.
Pros
Cons
Best for: A 1 kg shaker for mixed pots when you want NPK 10:5:11 printed on the listing and will keep a heavy rate off young plugs.
Less suitable: Plug plants at a heavy rate, anyone who needed a printed six-month window, or a deep review file.
Specifications
Common questions
What NPK does the Doff listing print?
A bullet says NPK fertiliser blend 10:5:11. It is the only listing in this comparison with an NPK on the amazon card.
How do you apply it?
Bullets name a shaker dispensing bottle. The listing has no grams-per-pot rate.
Does it print a six-month claim?
No. No month window is printed. The bullets say plants receive nutrients when they require them.
Topline Grow More 6-month plant food, 2 kg, is an all-purpose granule tub at about £17.99, with a thank-you card and a model field that says Gro-Sure. amazon.co.uk shows 4.3 from 71 reviews. Bullets say premix with compost or topsoil, add to the planting hole, or top-dress, then water in to activate. They name flowers, fruits, vegetables, roses, shrubs, trees, baskets and containers. The listing warns that overdosing can damage plants. One reviewer burned plants by using too much and said they would stay with Miracle-Gro. Several deliveries arrived with a rigid plastic tub split at the corners and granules loose in the carton. It is a six-month blend. It is not a Westland Gro-Sure tub and not Growmore 7:7:7. At about £17.99 it is the dearest single 2 kg row here.
Pros
Cons
Best for: A 2 kg all-purpose charge for pots and beds if you will stay inside the rate and accept a rigid tub.
Less suitable: Anyone who wanted the cheaper 2 kg Westland tub, a printed NPK, or a pack that arrives intact more often.
Specifications
Common questions
How do you apply the Topline 2 kg granules?
Bullets say premix with compost or topsoil, add to the planting hole, or use as a top dressing, then water in to activate.
Does the listing warn about overdosing?
Yes. The listing says do not exceed application rates, because overdosing can damage plants.
What pack size is printed?
The title and the item weight are 2 kg. The unit-count field is 1 count. Both figures are copied as printed.
Seven amazon.co.uk listings were scored from the stored pages and the UK review notes already on file. There is no laboratory test. The figure beside each product is the star line on a 1 to 10 scale, so 4.5 becomes 9.0. That figure is not the award. The top pick is the 2 kg all-purpose granule with a six-month claim and a usable review file. The best value is the shaker that prints an NPK at the lower shelf price. The highest star line does not take either award. The weights below sum to 100.
Release claim and plant group
30%A printed month window, and a title that matches all-purpose, rose and shrub, or ericaceous plants. A pack you reapply every four to six weeks is a different product. An ericaceous jar is not scored as an all-purpose winner.
Printed analysis and application
25%An NPK on the amazon listing, plus a method you can follow: shaker, premix, or water in. A maker-page analysis is not copied onto a card that does not print one. A missing gram rate is a gap, not a guessed number.
Pack size versus the job
25%A small shaker for a few pots, a 2 kg tub for beds, a multi-jar case only if you will use it. Clashes between the title weight and the item-weight field stay visible. A split tub in the reviews counts against that pack.
Amazon review evidence
20%The star rating on amazon.co.uk, then how many reviews sit behind it. A 4.6 from a thin written sample does not outrank a larger file on a pack that states the job. One plant-kill report is kept, and it is not treated as a measured cause.
Match the month claim and the plant group before you match the star line. Prices below are amazon.co.uk shelf prices from this capture. This is not a laboratory test.
Slow release fertiliser on a UK shelf is usually a garden granule that claims about three or six months of feed. The Royal Horticultural Society uses a stricter split. Controlled-release means a coated inorganic granule. Slow-release, in that glossary, means an organic meal or pellet that microbes break down. This comparison follows the shop phrase and looks at coated or blended granules. An organic meal is a different product.
Growmore 7:7:7 is a general feed you reapply every four to six weeks. A tub that happens to say Grow More can still be a six-month blend. Read the month line. The name alone does not make them the same product.
Camellia and blueberry need the ericaceous jar. A six-month all-purpose tub is the wrong plant group, even when the review file is larger.
Do not add a full-rate liquid on the same day as a full granule rate, and do not push a heavy feed in late autumn. Water the granules in, and keep them off stems, ponds and drains.
Start with the technology. A coated granule releases with warmth and moisture. A blend with a faster fraction can green sooner and can burn plugs if you exceed the rate. A printed window of about three or six months is the shop claim to look for. A pack that says every four to six weeks is a different aisle. Then match the plants. Mixed baskets and borders take an all-purpose granule.
Great Britain packs should show a statutory declaration under the Fertilisers Regulations 1991. In this comparison only Doff prints an NPK on the amazon card, 10:5:11. The Boost maker page lists 17.8-7-15.5. That stays a maker statement, because the amazon card does not print it. Goulding's 1:0:0 mixing field is not an NPK. A missing gram rate means you cannot check the dose from the listing alone. Pack size is the last filter. A 720 g or 1 kg shaker suits a few pots. A 2 kg tub suits beds.
Three typical situations, each with a recommendation from this comparison.
You want one spring mix-in for baskets and troughs. The feed already in peat-free compost often lasts about three to four weeks. Westland Boost 2 kg is the top pick at about £11.64, with 4.5 from 181 reviews. The listing claims six months, spelled 6-moth. Water it in. Some tubs arrive split.
You want a jar titled for rose, tree and shrub. Goulding G60115 is 720 g at about £9.37, with an up-to-six-month claim and 4.4 from 143 reviews. A shopper who also bought the general-purpose Goulding said both jars printed the same contents list. The listing does not print an NPK. The item-weight field is 750 g.
Acid-loving plants need the ericaceous jar, not an all-purpose feed. Westland Ericaceous Plant Food Granules, 900 g, claim three months at about £6.00, with 4.5 from 282 reviews. The item-weight field is 770 g. Reviews include greener foliage and plant-kill reports. Feed again around the three-month window.
The top pick for mixed baskets and beds is Westland Boost Slow Release Plant Food 2 kg at about £11.64. The listing claims a six-month nutrient supply, the bullet spells that line 6-moth, and amazon.co.uk shows 4.5 from 181 reviews. Reviewers describe one spring application on baskets, troughs and raised beds. The tub can arrive split. The best value is Doff Multipurpose Controlled Release Fertiliser 1 kg at about £8.38. It is the only listing here that prints NPK 10:5:11, at 4.4 from 24 reviews. A reviewer reported burnt roots on plug plants, and the card does not print a month window. Neither award is a laboratory test.
Doff Multipurpose Controlled Release Fertiliser 1 kg
Printed NPK 10:5:11 on a 1 kg shaker at about £8.38. The file is 4.4 from 24 reviews, and a plug-plant burn report stays on the page.
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 used for this page in October 2026. Prices, stars and review counts are from the seven amazon.co.uk listings. A maker-page NPK is not the amazon card. There is no laboratory test and no Which? winner among these jars.
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.
