Limestone (Fine Powder) is a finely ground calcitic limestone that reacts quickly in the soil to raise pH and supply plant-available calcium. Ground to pass 100 mesh, it carries far more surface area than coarse or granular grades, so it breaks down and neutralizes soil acidity within the current growing season instead of over several years.
This grade is built for growers who need a response now: correcting acidic potting mixes and living soils, setting pH before a planting, or topping up calcium in containers and raised beds. It is the same high-purity Canadian limestone as our coarse grade, ground fine for speed and even blending.
Calcium plays a critical role in plant development, supporting strong cell walls, healthy root growth, and overall plant resilience.
Benefits
- Fast-acting: the fine grind reacts within the current growing season
- Adds calcium for strong, healthy plant growth
- Raises and stabilizes soil pH quickly
- Improves the availability of phosphorus
- Low in magnesium compared to dolomitic lime, ideal where magnesium is already adequate
- Blends evenly into potting soils, living soils, and container media
- Supports beneficial soil microbial activity
Fine Powder vs. Coarse Limestone
Particle size controls how fast limestone works. This fine powder grade has a very high surface area, so it reacts quickly and is best suited to fast pH correction, blending into soil mixes, and container growing.
Our coarse grade breaks down slowly and is better for long-term, slow-release conditioning in the field. Choose fine for speed and uniform blending. Choose coarse for long-term soil maintenance.
Best Uses
Potting Mixes & Living Soils
Fine limestone blends evenly through peat, coir, and compost-based mixes. It corrects the natural acidity of peat and coir and sets a stable pH before planting, which makes it a standard component in living soil builds.
Containers & Raised Beds
In smaller soil volumes, even distribution matters. The fine grind spreads uniformly through the mix, so every part of the root zone gets consistent calcium and pH support.
Fast pH Correction
When a soil test shows low pH and you need results this season, fine limestone acts faster than coarse or granular grades.
Application
Potting Mix & Living Soil Blending
Blend 3 to 6 g per litre of mix (about 0.5 to 1 cup per cubic foot, or 5 to 10 lbs per cubic yard). Use the lower end for coir-based mixes and the higher end for heavily peat-based mixes. Mix thoroughly and moisten before planting.
Garden & Small Areas
Apply 500 g to 1 kg per 10 m² (1 to 2 lbs per 100 ft²) based on soil test results. Incorporate into the soil where possible. The fine grade begins reacting within the current growing season.
Field Application (Agricultural Use)
Apply 1 to 2 tons per acre depending on soil conditions and pH levels. Incorporate before planting for the fastest, most uniform response.
Soil pH Management
Most plants prefer a soil pH between 6.0 and 7.0. Because fine limestone reacts quickly, it can be used to correct pH ahead of or close to planting. Retest after one season to confirm results before reapplying.
Soil Testing Recommended
Limestone application should be based on soil conditions. Applying without testing can lead to over-liming, which may reduce nutrient availability.
Our laboratory soil analysis includes sampling, detailed results, and tailored application recommendations, so you know exactly what your soil needs and how much to apply.
Understanding Soil pH, Calcium, and Heavy Metals
Aluminum is naturally present in most soils, but under acidic conditions it dissolves into a form that plants can absorb. In this soluble form, aluminum damages root tips, limiting growth, water uptake, and nutrient access.
Applying limestone supplies calcium and raises soil pH, which makes aluminum and other heavy metals far less available to plants. The result is deeper, stronger roots that use nutrients more efficiently.
How Calcium Helps Limit Heavy Metal Uptake
Calcium reduces heavy metal uptake in three key ways:
1. Raising Soil pH In acidic soils, metals are more soluble and easier for plants to absorb. Limestone helps keep more of these metals bound in the soil rather than entering the plant.
2. Competing at the Root Level Calcium shares the same uptake pathways as metals like cadmium, lead, and nickel. When sufficient calcium is present, plants absorb more calcium and less of these competing metals.
3. Strengthening Root Systems Calcium fortifies cell walls and root membranes, helping roots better regulate what enters the plant and reducing passive uptake of unwanted elements.
Heavy Metals Most Affected
Improving soil pH and calcium levels can help reduce the availability and uptake of:
- Cadmium (Cd)
- Lead (Pb)
- Nickel (Ni)
- Zinc (Zn)
- Aluminum (Al)
- Manganese (Mn)
Why This Matters
Healthy soil is about balance, not just nutrients. By supplying calcium and improving soil pH, limestone helps create a more stable soil environment where plants can grow efficiently, access nutrients, and limit the uptake of unwanted elements, supporting cleaner, healthier crops.
Typical Analysis
- Calcium Carbonate (CaCO₃): 97.38%
- Calcium (Ca): 39%
- Magnesium (Mg): 0.43%
- Particle size: minus 100 mesh (99% passing 100 mesh, 95% passing 200 mesh)
High-purity calcitic limestone with a high neutralizing value and low magnesium content.
[DOWNLOAD - FINE LIMESTONE LAB ANALYSIS (PDF)
DOWNLOAD - ORGANIC DECLARATION LIMESTONE (PDF)
This product complies with Canada's Organic Production Systems General Principles and Permitted Substances Lists (CAN/CGSB-32.310-2026, CAN/CGSB-32.311-2026). Approved for use in organic production.
