Granulated lime: calcium carbonate granules that spread like a fertiliser and break down into flour
Lift acid soil back towards pH 6.5 for vegetables, lawns, fruit and brassicas, with a granule you can scatter by hand or spreader and no dust. It is natural limestone ground to a fine flour, then bound into hard 2 to 5 mm granules with a water-soluble binder. Once wet, the binder dissolves and each granule falls back into flour where it landed: 88% passes a 0.1 mm sieve. That fine fraction is what reacts with soil acidity, so you get the speed of a fine lime with the handling of a granule.
Analysis is 55% calcium oxide (about 98% calcium carbonate), neutralising value 54, reactivity 97%. It is a calcitic lime, under half a percent magnesium, so it corrects pH and adds calcium without loading the soil with magnesium. For pots, drenches and small beds, our micronised Garden Lime Powder is the better tool; this one is for lawns, open ground and anything you would rather spread than sprinkle.
What it's for
- Lawns on acid soil: where a test reads below pH 5.5, a granule settles through the turf and does not coat the grass or blow about
- Vegetable beds and allotments: most crops want pH 6.0 to 7.0, and brassicas do best at 6.5 to 7.5, where clubroot struggles
- Fruit trees and bushes: apples, pears, plums, currants and gooseberries sit happiest around pH 6.0 to 6.5. Not blueberries
- Large areas: borders, orchards and new lawns, where a powder is slow to spread evenly
- A calcium source: 39% elemental calcium, more than gypsum, for ground that is both acid and short of calcium
Granules, powder or agricultural lime?
Granulated lime (this product)
- Hard 2 to 5 mm granules that break down to flour on wetting
- Spreads cleanly by hand or spreader, with no dust
- Best for lawns, beds, borders and anything over a few square metres
Garden Lime Powder, micronised to 63 microns
- The finest grind and the quickest reaction; suspends in water for a drench
- Dusty on a breezy day, and hard to spread evenly over a lawn
- Best for pots, potting mixes, drenches and small beds
Coarse agricultural lime
- Variable purity and particle size, from dust to grit
- Only the fine fraction reacts in the first season; the rest can take years
British limestone, milled and granulated in the UK, then weighed and packed in small batches at our workshop in Stockport. Not sure whether your soil needs lime or the opposite? Start with how to raise soil pH, or how to lower it if the test reads high.
The science: how granulated lime raises soil pH
Calcium carbonate (CaCO₃) is the mineral in limestone and chalk, and the standard liming material in UK agriculture. It barely dissolves in plain water but dissolves readily in acid, and in soil that acid comes from dissolved carbon dioxide and the organic acids released by roots and microbes. As it dissolves it consumes acidity and releases calcium, so pH rises.
CaCO₃ + 2H⁺ → Ca²⁺ + H₂O + CO₂. It needs soil acidity to drive it, so it slows as the soil nears neutral. That is why calcium carbonate is a gentle liming material compared with quicklime or hydrated lime, both of which are caustic.
Why fineness matters, and why this granule is made from flour
Lime reacts at the particle surface, so the finer it is, the faster it works. In an incubation study, Jones and Mallarino (2016) found that limestone finer than 150 microns was 97% as effective as pure calcium carbonate, while particles of 0.85 to 2.4 mm were only 39% effective. Holland et al. (2018) reach the same conclusion for UK soils.
A solid granule would sit at the slow end of that range. This one is limestone flour held together with a water-soluble binder: on the first rain or watering it falls apart where it lands, and 88% of what reaches the soil is under 100 microns. The granule is simply a dust-free way to deliver fine lime.
What the manufacturer's trial showed
On sandy soil, a top-dressing of 24.8 g/m² raised the pH of the top 2 to 3 cm by 0.9 units within four weeks. Two years later the same single application had raised pH by 0.6 at 14 to 15 cm. Fine lime acts quickly where it lands, but it moves down through the soil slowly. A top-dressing is a surface treatment; to correct the whole root zone before planting, fork the lime in at the larger rates on the How to Use tab.
What pH does for the plant
Nutrient availability
Plant-available phosphorus is highest between pH 5.5 and 6.5 (Holland et al., 2018). Below about pH 4.2, aluminium reaches levels toxic to most roots; above about 7.5, iron and manganese begin to lock up, which is why liming past the target is a mistake.
Most UK soils are under target
The UK target is pH 6.5 for cultivated ground and 6.0 for grassland (Goulding, 2016), yet more than 40% of arable and 56% of grassland soils fall below it (Holland et al., 2018). If your beds have never been limed, a test is worth the few pounds.
Soil life follows pH
Across a long-term liming trial from pH 4.0 to 8.3, bacterial diversity rose markedly with pH while fungal diversity barely changed (Rousk et al., 2010). Earthworms, particularly the deep-burrowing species, also tend to increase after liming (Holland et al., 2018).
Full analysis
| Property | Value |
|---|---|
| Calcium carbonate (CaCO₃) | About 98% |
| Calcium as CaO / as Ca | 55% / 39.3% |
| Magnesium as MgO | Under 0.5% (calcitic, not dolomitic) |
| Neutralising value (as CaO) | 54 minimum |
| Reactivity (HCl) | 97% |
| Granule size | 2 to 5 mm |
| Fineness after breakdown in water | 99% under 0.315 mm; 88% under 0.1 mm |
| Moisture | Under 0.5% |
Expected average analysis, dry basis. Meets the "Limestone, fine quality" liming material specification under EC Regulation 2003/2003. Neutralising value is the same as our Garden Lime Powder; the difference between them is form, not chemistry.
- Holland, J.E. et al. (2018). Liming impacts on soils, crops and biodiversity in the UK: A review. Science of the Total Environment, 610–611, 316–332.
- Goulding, K.W.T. (2016). Soil acidification and the importance of liming agricultural soils with particular reference to the United Kingdom. Soil Use and Management, 32(3), 390–399.
- Jones, J.D. and Mallarino, A.P. (2016). Influence of source and particle size on agricultural limestone efficiency at increasing soil pH. Proceedings of the North Central Extension-Industry Soil Fertility Conference, 32, 91–96.
- Rousk, J. et al. (2010). Soil bacterial and fungal communities across a pH gradient in an arable soil. The ISME Journal, 4(10), 1340–1351.
- Manufacturer's data sheet, application recommendations and trial reports (2022–2025), on file.
- Royal Horticultural Society. Clubroot; Lime and liming. RHS Advice.
- AHDB (2023). Nutrient Management Guide (RB209), Section 1.
How to use granulated lime to raise soil pH
Only lime soil that a test says is too acid for what you grow. A probe or a garden-centre kit is enough: take soil from 10 to 15 cm down in several spots, mix it, and test that. If it already reads 6.5 or above, put the bag away; lime on neutral ground adds nothing and can lock up iron and manganese.
Keep it away from blueberries, cranberries, rhododendrons, azaleas, camellias, pieris and heathers. Do not lime ground you will plant potatoes in that season; a higher pH encourages common scab. For calcium without a pH change, use granulated gypsum.
What you're aiming for
| What you grow | Target pH | Lime when the test reads |
|---|---|---|
| Most vegetables, soft fruit, flowers | 6.0 to 7.0, ideally 6.5 | Below 6.0 |
| Brassicas (cabbage, sprouts, kale, swede) | 6.5 to 7.5 | Below 6.5, or anywhere clubroot has shown |
| Lawns | 5.5 to 7.0 | Below 5.5 |
| Apples, pears, plums, currants, gooseberries | 6.0 to 6.5 | Below 6.0 |
| Potatoes | 5.0 to 6.0 | Rarely; do not lime before potatoes |
| Blueberries, rhododendrons, camellias | 4.5 to 5.5 | Never |
Target ranges from RHS advice and AHDB RB209.
How much to use
Lime is dosed by how far the pH has to move and how strongly your soil resists the change; clay and peaty soils need more than sand for the same shift. Rates below are grams of granules per square metre for each half unit of pH you need to raise (for example, 5.5 to 6.0). A full unit is double.
Option A: full correction, dug in before planting
| Soil type | Beds, borders and new lawns (dug in) | Established grass (surface only) |
|---|---|---|
| Sandy | 300 g/m² | 225 g/m² |
| Light loam | 350 g/m² | 250 g/m² |
| Medium loam, clay or silt | 400 g/m² | 300 g/m² |
Derived from the manufacturer's lime factors, which follow the AHDB RB209 method. Do not put more than about 400 g/m² down in one go: split larger amounts between autumn and spring, and retest between.
Option B: top-dressing on established ground
| Soil type | Beds and borders, raked in | Lawns and grass |
|---|---|---|
| Sandy | 30 g/m² | 25 g/m² |
| Light loam | 40 g/m² | 30 g/m² |
| Medium loam, clay or silt | 50 g/m² | 40 g/m² |
The manufacturer's trial-based rates, converted to g/m² and rounded. The RHS figure for an acid lawn, about 50 g/m² of ground limestone in autumn or winter, sits in the same band.
Digging a bed or sowing a lawn: Option A, forked in, so the whole root zone is right from day one. Established lawn, planted border or fruit trees: Option B, raked or watered in, then retest in six to eight weeks and repeat to the test. The risk of Option B is a slower result, not a ruined bed.
Rates at a glance
| Job | Rate | When |
|---|---|---|
| Vegetable beds, borders, allotments | Option A, forked into the top 15 cm | Autumn or winter, done by spring sowing |
| Brassica beds and clubroot ground | Option A, aiming at pH 7.0 or above; top up each rotation | Autumn before a spring planting |
| Lawns (only below pH 5.5) | 25 to 50 g/m² per application; water in | Autumn to early spring, not in drought |
| New lawns and seedbeds | Option A: 225 to 300 g/m² per half unit, raked into the top 5 to 10 cm | At least two weeks before sowing or turfing |
| Fruit trees and bushes (not blueberries) | Option B: 30 to 50 g/m² over the root area, per half unit | Late autumn to late winter |
| Pots and potting mixes | Use Garden Lime Powder: 1 to 3 g per litre of compost, or 0.5 to 1 g per litre of water as a drench | Any time |
Lime does not cure moss: moss is mainly shade, wet and compacted soil. Keep lime a month away from manure and from fresh nitrogen feeds, which lose nitrogen as ammonia if they meet fresh lime. Lime in autumn, manure in late winter.
Which bag size do you need?
Area in m² × rate × half-units = grams needed. A 10 m² loam bed at pH 5.5 going to 6.5 is two half-units: 10 × 350 × 2 = 7,000 g, so a 9 kg bag.
| Bag | Lawn top-dressing (40 g/m²) | Bed, loam, half a unit (350 g/m²) | Bed, loam, one full unit (700 g/m²) |
|---|---|---|---|
| 1.5 kg | 37 m² | 4 m² | 2 m² |
| 4 kg | 100 m² | 11 m² | 6 m² |
| 9 kg | 225 m² | 26 m² | 13 m² |
| 15 kg | 375 m² | 43 m² | 21 m² |
Sand needs about 15% less than loam and clay about 15% more.
Step by step
- Test the soil in several spots, 10 to 15 cm down, and note the soil type: a moist handful that balls and shines is clay, one that crumbles is loam, one that falls apart is sand.
- Work out the dose. Count the half-units to your target, pick Option A or B, and multiply by the area. Weigh it out.
- Spread it by hand in two passes at right angles, or with a spreader on a low setting.
- Fork it in or water it in. The binder dissolves and each granule falls back to flour.
- Retest after six to eight weeks for a top-dressing, or the following spring for a dug bed, then every two or three years.
Once the pH is right, feed. Polyhalite adds potassium, magnesium, sulphur and calcium without moving pH, and kieserite covers magnesium if a test shows it is short. Keep lime a month away from fresh nitrogen feeds, including our lawn fertiliser.
Keep the bag sealed and dry: the binder is water-soluble, so damp granules soften and clump. Ground limestone is non-toxic and non-hazardous. Wash your hands after spreading, as with any soil product.