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Old Cobblers Farm™ Wicked Organics 0-12-0 Fertilizer - Rock Phosphate
Learn how to use organic 0-12-0 rock phosphate fertilizer for stronger roots and better blooms. OMRI-listed application rates and tips.
Old Cobblers Farm™ Wicked Organics 0-12-0 Fertilizer – Rock Phosphate
Rock phosphate is a naturally occurring mineral mined from ancient marine deposits rich in calcium phosphate. It has been used as a soil amendment for over a century and remains one of the most trusted phosphorus sources in organic and sustainable agriculture. The mineral is crushed and finely ground to increase surface area, which helps soil biology break it down into plant-available forms more efficiently.
Unlike water-soluble phosphorus fertilizers, rock phosphate does not dissolve on contact with moisture. Instead, it relies on soil acidity and microbial activity to slowly convert its phosphorus into forms plant roots can absorb. This means it works best in soils with a pH below 7.0 and in biologically active soils rich in organic matter.
Gardeners and farmers choose rock phosphate when they want to build long-term phosphorus reserves without repeated applications. A single heavy application can feed the soil for 3-5 years, making it both cost-effective and low-maintenance.
NPK
0-12-0
Type
Organic
Derived From
Finely ground natural rock phosphate (calcium phosphate mineral deposits)
Best For
Tomatoes|Peppers|Fruit Trees|Root Vegetables|Bulbs|Flowering Perennials|Strawberries|Garlic
Brand
Wicked Organics
NPK Breakdown
N
0
N/A — Rock phosphate contains no nitrogen, making it ideal for targeted phosphorus supplementation without stimulating excess leafy growth.
P
12
Delivers slow-release phosphorus that promotes vigorous root development, abundant flowering, and strong fruit and seed production.
K
0
N/A — Rock phosphate contains no potassium. Pair with a potash source like 0-0-60 or Greensand for complete P-K supplementation.
What Is It ?
Rock phosphate (0-12-0) is a naturally mined mineral fertilizer that delivers slow-release phosphorus directly to your soil, feeding plants steadily over months and even years. Unlike synthetic phosphorus sources such as triple superphosphate that dissolve quickly and can leach away, rock phosphate breaks down gradually as soil microbes and mild acidity unlock its nutrients — making it one of the most efficient, long-lasting ways to build phosphorus levels in your garden or farm.
Phosphorus is the engine behind root growth, flower production, and fruit development. Without adequate phosphorus, plants struggle to establish strong root systems, blooms are sparse, and yields suffer. Rock phosphate solves this by raising your soil's available phosphorus naturally, without the risk of salt buildup or nutrient runoff that comes with synthetic alternatives.
Old Cobblers Farm™ Wicked Organics 0-12-0 Rock Phosphate is finely ground for faster nutrient availability and is approved for organic use. Whether you're preparing garden beds in spring, planting fruit trees, or building long-term fertility on your farm, this product delivers the phosphorus your soil needs — the way nature intended.
When To Apply ?
Start with a soil test to confirm your phosphorus levels are actually low — excess phosphorus can lock out other nutrients like zinc and iron. If your soil pH is above 7.0, consider using a more soluble phosphorus source or amending with sulfur to lower pH first. For garden beds, broadcast the recommended rate evenly across the surface, then incorporate it into the top 4-6 inches of soil. For trees and shrubs, dig a trench around the drip line 4-6 inches deep, spread the rock phosphate evenly, and backfill. Water thoroughly after application.
How to Apply ?
1.
Soil Test
Test your soil pH and phosphorus levels first. Rock phosphate works best in acidic soils (pH below 7.0).
2.
Calculate Rate
Calculate how much rock phosphate you need based on soil test phosphorus recommendations.
3.
Broadcast
Broadcast evenly over the garden bed or around the drip line of trees and shrubs.
4.
Incorporate
Work into the top 4–6 inches of soil with a rake or tiller for root-zone placement.
5.
Water In
Water the area thoroughly after application to begin slow mineral phosphorus release.
6.
Longevity
Reapply every 3–5 years based on follow-up soil tests. Rock phosphate releases very slowly over multiple seasons.
7
Broadcast
Broadcast evenly over the garden bed or around the drip line of trees and shrubs.
How To Store
Rock phosphate is a low-toxicity natural mineral, but the fine powder can irritate eyes, skin, and lungs during application. Wear a dust mask, gloves, and eye protection when spreading. Store in a cool, dry location in the original sealed bag.
FAQs
1.
What is rock phosphate fertilizer?
Rock phosphate is a natural, mined mineral fertilizer with an NPK ratio of 0-12-0, providing 12% phosphorus (P₂O₅) with no nitrogen or potassium. It is one of the oldest and most natural phosphorus sources available, formed from ancient marine deposits over millions of years. Rock phosphate releases phosphorus very slowly as soil acids and microbial activity gradually break down the mineral particles — providing sustained phosphorus availability over months to years rather than weeks. Old Cobblers Farm™ Wicked Organics 0-12-0 Rock Phosphate is an OMRI-Listed organic phosphorus amendment for long-term soil building.
2.
What is rock phosphate used for in the garden?
Rock phosphate is used to build long-term phosphorus reserves in garden soil. Unlike fast-acting synthetic phosphorus, rock phosphate breaks down gradually, providing a sustained phosphorus supply that supports root development, flowering, and fruiting over multiple growing seasons. It is especially popular in organic gardens, permaculture systems, and long-term soil improvement programs where building lasting soil fertility is the goal. Rock phosphate also supplies calcium and trace minerals. Old Cobblers Farm™ Wicked Organics 0-12-0 Rock Phosphate is ideal for gardeners investing in long-term soil health rather than quick-fix nutrition.
3.
How do I apply rock phosphate?
Apply rock phosphate by broadcasting 5–10 pounds per 100 square feet and incorporating deeply into the top 6–8 inches of soil. Because rock phosphate does not move through soil and releases nutrients slowly, thorough incorporation into the root zone is essential. For new garden beds, mix into the soil during initial preparation. For established beds, work into the soil surface as deeply as practical. Apply in fall or early spring to allow maximum time for breakdown before peak growing season. Old Cobblers Farm™ Wicked Organics 0-12-0 Rock Phosphate is most effective when deeply incorporated into the planting zone.
4.
What is the difference between rock phosphate and triple superphosphate?
Rock phosphate (0-12-0) is a natural, slow-release phosphorus source that breaks down over months to years, ideal for organic programs and long-term soil building. Triple superphosphate (0-46-0) is a concentrated, water-soluble form providing nearly four times the phosphorus that becomes available quickly. Rock phosphate works best in acidic soils (pH below 6.5) where it dissolves more readily, while TSP is effective across all pH levels. Choose rock phosphate for slow, sustained feeding and TSP for immediate phosphorus needs. Old Cobblers Farm™ offers both Wicked Organics Rock Phosphate and Wicked Growth 0-46-0 TSP.
5.
Does rock phosphate work in alkaline soil?
Rock phosphate is less effective in alkaline soils (pH above 7.0) because the mineral requires soil acids to break down and release plant-available phosphorus. In neutral to alkaline soils, rock phosphate may take significantly longer to become available or may remain largely unavailable to plants. For alkaline soils, triple superphosphate (0-46-0) or bone char are better phosphorus choices because they are already in plant-available forms. A soil test indicating both pH and phosphorus levels helps determine the best option. Old Cobblers Farm™ Wicked Organics Rock Phosphate performs best in soils with pH below 6.5.
6.
How does rock phosphate compare to bone meal?
Rock phosphate (0-12-0) and bone meal (3-15-0) both provide phosphorus but differ in origin, release speed, and additional nutrients. Bone meal is an animal byproduct that releases phosphorus more quickly and also provides nitrogen and calcium. Rock phosphate is a mined mineral that releases phosphorus much more slowly but persists in soil for longer. Bone meal may attract digging animals, while rock phosphate does not. Both are OMRI-Listed for organic use. Old Cobblers Farm™ offers Wicked Organics Rock Phosphate for long-term soil building and Bone Meal for faster phosphorus availability.
7
What is the NPK of rock phosphate?
Rock phosphate has an NPK ratio of 0-12-0, meaning it provides 12% phosphorus (P₂O₅) with no nitrogen or potassium. While 12% is lower than concentrated synthetic phosphorus sources like triple superphosphate (46%), rock phosphate compensates with its extremely long residual effect in soil — a single heavy application can supply phosphorus for 3–5 years. It also provides 20–30% calcium and various trace minerals not found in synthetic alternatives. Old Cobblers Farm™ Wicked Organics 0-12-0 Rock Phosphate delivers lasting organic phosphorus from a single natural mineral source.