Sulphur Granules are 90% elemental sulphur in a clean, granular form that spreads easily by hand or spreader with minimal dust. Elemental sulphur is the proven, economical way to lower the pH of alkaline, high-pH, and saline-alkali (sodic) soils, bringing them back into the range where nutrients stay available and plants can thrive.
Rather than reacting on contact, the granules work with the soil's own biology: as they break down, they release acidity gradually while also supplying sulphur in the form plants use, both adjusting soil pH and feeding the soil.
How it works
Elemental sulphur is not acidic on its own. Once in contact with moist, aerated soil, naturally occurring sulphur-oxidizing bacteria, including Thiobacillus, oxidize it to sulphate, releasing acidity that lowers pH. Because the change is biological, it is gradual: most of the activity occurs in the weeks after application, but a full pH shift usually takes several months to a year, and repeat applications build the soil's sulphur-oxidizing populations over time.
Warm, moist, well-aerated soil speeds the process, while cold or compacted ground slows it. Incorporating granules works better than leaving them on the surface, and soils high in free lime resist change and need more. A soil test is the only reliable way to know how much your soil requires.
Who it's for
Sulphur Granules suit any grower looking to lower a high soil pH, from home beds to field scale.
Acid-loving plants: Blueberries, rhododendrons, azaleas, camellias, and heathers all prefer acidic soil, and hydrangeas turn blue as pH drops. Elemental sulphur is the standard tool for creating and holding that lower pH.
Alkaline and high-pH soils: Where high pH is locking up iron, manganese, phosphorus, and other nutrients, sulphur brings the soil back into a workable range and can help manage saline-alkali (sodic) ground.
Field, orchard, and vineyard: Broadcast and incorporated ahead of planting, sulphur corrects pH across larger blocks and builds sulphur for the season. Sandy soils need less than clay or calcareous ground. For acreage-scale programs, Sulphur Granules are available in 1000 kg (one tonne) totes: https://www.optimizeorganics.ca/products/sulfur-granules-90-s-1000kg
Cannabis: In soil or living-soil beds, which do best in slightly acidic conditions, sulphur brings an alkaline mix into range while adding sulphur. Incorporate and allow time to react before planting.
How to use
Base the rate on a soil test. The amount needed depends on your starting pH, target pH, and soil texture, so test first. All rates below are for this product as supplied.
Apply and incorporate before planting. Broadcast evenly, work into the top 15 to 20 cm (6 to 8 in), then keep the soil moist. Oxidation is biological and needs soil temperatures consistently above about 13°C (55°F), so apply at least 6 to 8 weeks before planting. Surface application without incorporation eventually reaches the same pH; it just takes longer.
Home and garden
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Lowering pH by about one unit takes roughly 0.8 to 3.5 lb per 100 sq ft (about 0.4 to 1.7 kg per 10 m²): the low end on sandy soils, the high end on clay.
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Around established plants, do not exceed 400 g per 10 m² (about 0.8 lb per 100 sq ft) at one time, once per season. Split larger amounts across seasons.
Broadacre and commercial
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Sulphur nutrition: 11 to 33 lb/ac (12 to 37 kg/ha), up to 55 lb/ac (62 kg/ha) for high-demand crops such as canola, brassicas, and alfalfa.
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pH correction, preplant on bare ground: 300 to 1,000 lb/ac (336 to 1,120 kg/ha) incorporated. Do not exceed 1,000 lb/ac in a single pass.
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pH correction, established stand: maximum 400 lb/ac (448 kg/ha) per application, once per year. Irrigate in after application.
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Apply in fall or early spring. Blends well with granular fertilizers for even spread.
Recheck before planting or reapplying. Retest at 8 weeks to gauge progress. pH can continue to drop for 6 to 18 months as oxidation completes, so measure before applying again.
Guaranteed analysis
Sulphur (S): 90%
Form: dry granular, for spreader or hand application with minimal dust.
Storage and safety
Store in a cool, dry place in the original container. Keep out of reach of children and pets, and do not ingest. Avoid skin and eye contact and avoid inhaling dust; wash hands and exposed skin after handling.
Elemental sulphur is a permitted substance for organic crop production under Canada's organic standards, CAN/CGSB-32.310-2026 and CAN/CGSB-32.311-2026, as a soil amendment.
