Jack’s Professional 21-5-20 All Purpose LX Fertilizer

JR Peters Jack’s 21-5-20 is a complete, potentially acidic formula engineered for moderate to high alkalinity water, keeping magnesium and phosphorus soluble for consistent uptake. As a lower-phosphorus alternative to 20-10-20, it supports compact, vigorous growth without excessive P. The balanced profile is perfect for hydroponic systems, soilless mixes, and greenhouse crops where solution stability matters.

Hydroponic Use & Tank-Mix Flexibility

This LX formula plays nicely in the tank—mix with 15-5-15, other Jack’s LX blends, and compatible partners like calcium nitrate and magnesium nitrate without diluting micronutrient concentrations. Use it as your stand-alone base or as part of a multi-tank program to fine-tune EC, pH, and growth stage needs. Count on predictable dissolving, clean mixing, and steady performance from vegetative growth through production.

Key features:

• Keeps Mg and P soluble in higher-alkalinity water for reliable uptake

• Potentially acidic, helping manage solution pH and reduce bicarbonate impact

• Lower-P alternative to 20-10-20 for tighter internodes and balanced growth

• Tank-mix compatible with 15-5-15, other Jack’s LX formulas, calcium nitrate, and magnesium nitrate

• Consistent, clean dissolving for hydroponics, soilless, and greenhouse fertigation

• For use on: All bedding and potted plants, can be used for plugs at low rates.