Water Soluble Fertilizers
Water-soluble fertilizers for soil, hydroponics, foliar spray, and drip irrigation
Water-soluble fertilizers dissolve completely in water and are designed for direct delivery to plant roots or leaves — without waiting for soil microbial breakdown. Whether you're looking for a water-soluble fertilizer for vegetables, a complete nutrient program for hydroponics, a foliar spray to correct a deficiency mid-season, or a reliable fertigation product for drip irrigation, every product in this collection is 100% water-soluble, suitable across common application methods, and designed for complete dissolution with no residue.
All products are CDFA registered, third-party tested for heavy metals, and backed by our 90-day guarantee. Made and distributed from Madera, California since 1989.
Who this collection is for
Shop by nutrient
How to choose the right water-soluble fertilizer
Need maximum nitrogen per pound
→ Urea 46-0-0. The highest-concentration nitrogen fertilizer available — fast green-up for lawns, vegetables, and field crops. Water in within 24–48 hours of application; avoid surface application above 85°F without incorporation — volatilization losses increase significantly in hot conditions.
Alkaline soil or acid-loving plants
→ Ammonium Sulfate 21-0-0 + 24% S. Supplies nitrogen and sulfur while gradually lowering soil pH. Ideal for blueberries, azaleas, and high-pH soils.
Calcium deficiency or blossom end rot
→ Calcium Nitrate 15.5-0-0 + 19% Ca. The standard calcium and nitrogen source for hydroponic and soil programs. Add to Tank A first — never mix in concentrate with phosphate or sulfate sources.
Early growth, root establishment, or transplanting
→ MAP 12-61-0. Highest-concentration phosphorus source with some nitrogen — the go-to for driving root development at planting and early vegetative stages.
Flowering and fruiting stage — maximize yield and quality
→ MKP 0-52-34. Nitrogen-free phosphorus and potassium — the standard bloom booster. Allows maximum fruit development without vegetative push. Keep separate from calcium in concentrate.
Chloride-sensitive fruit or vegetable crops
→ Potassium Sulfate 0-0-53 + 17% S. The preferred potassium source for tomatoes, peppers, berries, and other crops where chloride reduces sugar content and shelf life.
Quick reference — all single-nutrient water-solubles
| Product | Analysis | Primary Role | Key Note |
|---|---|---|---|
| Urea | 46-0-0 | Highest-concentration nitrogen | Water in within 24–48 hours of application — urea volatilizes as ammonia on warm exposed soil. Volatilization risk increases significantly above 85°F; avoid surface application in hot weather without incorporation. |
| Ammonium Sulfate | 21-0-0 + 24% S | Nitrogen + sulfur, soil acidification | Gradually lowers soil pH over time. Best for alkaline soils and acid-loving crops. |
| Calcium Nitrate | 15.5-0-0 + 19% Ca | Nitrogen + calcium | Tank A only. Never mix in concentrate with phosphate or sulfate sources — forms insoluble precipitate. |
| Potassium Nitrate | 13-0-46 | Nitrogen + potassium, chloride-free | Ideal for chloride-sensitive crops needing both N and K. Common in bloom-stage hydroponic programs. |
| MAP | 12-61-0 | Highest-concentration phosphorus + N | Best for root establishment. Keep separate from calcium in concentrated stock solutions. |
| MKP | 0-52-34 | Phosphorus + potassium, nitrogen-free | Standard bloom booster. Nitrogen-free allows fruit development without vegetative push. Keep separate from calcium. |
| Potassium Sulfate | 0-0-53 + 17% S | Potassium + sulfur, chloride-free | Preferred K source for sensitive fruit and vegetable crops. Keep separate from calcium in concentrate. |
| K-Mag | 0-0-22 + 11% Mg + 22% S | Potassium + magnesium + sulfur | Three nutrients in one. Ideal when K and Mg are both deficient. Avoid mixing in concentrate with calcium. |
| Potassium Chloride | 0-0-62 | Highest-concentration potassium, economical | Most cost-effective K source. Not for chloride-sensitive crops — use Potassium Sulfate instead for tomatoes, peppers, and berries. |
Crop-specific formulas — pre-blended with chelated micronutrients
If you'd rather not build a program from individual components, Greenway Biotech's specialty crop fertilizers do the work for you. Each is pre-blended with the exact NPK ratio for that crop's peak demand stages, plus a full suite of chelated micronutrients (iron, zinc, manganese, copper, boron, molybdenum). Chelated micronutrients help keep iron, zinc, manganese, and copper available in solution and accessible to plants — especially important in intensive feeding programs where pH fluctuations would otherwise lock up non-chelated forms.
Frequently asked questions
What is the difference between water-soluble and slow-release fertilizers?
Water-soluble fertilizers dissolve immediately and are available for plant uptake within hours of application — no microbial breakdown required. This makes them ideal for fast correction of deficiencies, hydroponic systems, fertigation, and foliar feeding. Slow-release and organic fertilizers depend on soil microbes and temperature to release nutrients over weeks or months, which is better suited for soil-building and long-season programs. Many growers use both: organic amendments as a seasonal foundation, water-soluble fertilizers for precision feeding during high-demand growth stages.
Can I use water-soluble fertilizers for foliar feeding?
Yes — all products in this collection are suitable for foliar application at appropriate dilution rates when properly dissolved, with one exception: Potassium Chloride (0-0-62) has a high salt index and is not recommended for foliar use — use Potassium Sulfate instead for foliar potassium delivery. For all other products, foliar feeding delivers nutrients through the leaf surface for rapid uptake and is most useful for correcting acute deficiencies or supplementing during peak demand. Apply in early morning or evening when temperatures are below 85°F and foliage is dry. Always test on a small area first and follow product-specific dilution rates — concentrated solutions will burn foliage.
Which products work best for hydroponics?
All single-nutrient water-solubles in this collection are compatible with hydroponic systems when properly dissolved — they leave no residue and don't clog lines. The most commonly used combination is: Calcium Nitrate (Tank A) + MKP or MAP (Tank B) + Potassium Sulfate (Tank B) + chelated micronutrients. For a complete pre-formulated system, see our Hydroponics Nutrients collection. Always keep calcium sources and phosphate/sulfate sources in separate concentrated stock tanks.
Are these fertilizers safe for drip irrigation and fertigation systems?
Yes — all products in this collection are solution-grade and dissolve completely without leaving residue that could clog emitters or injectors. The one critical rule: never mix calcium-containing fertilizers (Calcium Nitrate) directly with phosphate or sulfate sources in concentrated stock solutions — they precipitate and clog lines. Always use separate A and B stock tanks and inject alternately or dilute fully before combining in the main line.
Are Greenway Biotech water-soluble fertilizers tested for heavy metals?
Yes. All products in this collection are third-party tested for heavy metal content. Results are available on our Heavy Metal Analysis page. Every product is CDFA registered and manufactured or distributed from our Madera, California facility.
For deeper guidance on water-soluble fertilizers and application methods: