Calphos Soft Rock Phosphate (25 lb bag)

The 25 lb Calphos Soft Rock Phosphate bag bridges the gap between a small garden package and the 50 lb farm-size bag. It is well suited to multiple vegetable beds, perennial plantings, small orchards, and other projects that require more coverage without committing to the largest package.

Product profile

Calphos is a finely ground mineral amendment that averages about 20% P₂O₅, including 3% available phosphate, and approximately 18% calcium. It releases phosphorus gradually, so it is most useful when incorporated into soil where roots can reach it. Apply it to correct a demonstrated need rather than as a routine addition to soil that already contains sufficient phosphorus.

Application guidance

• For phosphorus-deficient soil, the general published rate is 5 lb per 100 sq ft; use less in more fertile soil.
• Published planting-hole guidance for trees and perennials ranges from 1–10 lb, depending on plant size.
• Use a current soil test and local recommendations to refine the rate for your crop and soil.

Organic status: This repackaged 25 lb size is not represented as organic or as listed or approved for certified organic production. The 50 lb original package carries its own organic-use listing; that status does not transfer to this repackaged size.

See our soft rock phosphate guide for additional planning information.

Compare this product with additional nutrient-specific fertilizers selected for garden and farm fertility programs.