• Wear gloves and eye protection when handling dry powder or concentrated solutions
• Avoid inhaling dust — use in well-ventilated areas or wear a dust mask when measuring
• Wash hands thoroughly after handling

• Store in a cool, dry place in the original sealed container
• Product is hygroscopic — it will absorb moisture from the air if exposed
• Keep out of direct sunlight and away from heat sources
• If powder clumps from moisture exposure, break it up — efficacy is not affected
• Keep away from children and pets

• Do not mix dry fertilizer with other products before dissolving in water
• Do not apply foliar sprays during peak sun hours or when temperatures exceed 90°F
• Avoid direct contact with plant stems and foliage when applying to soil
• Water thoroughly after soil application to prevent root burn

• Eye contact: Flush with clean water for 15 minutes. Seek medical attention if irritation persists
• Skin contact: Wash affected area with soap and water
• Ingestion: Do not induce vomiting. Contact Poison Control (1-800-222-1222) or seek medical attention
• Inhalation: Move to fresh air. Seek medical attention if symptoms persist

Refer to the Safety Data Sheet (SDS) for complete safety information.

Tomatoes are among the most potassium-demanding crops, especially during fruiting. Potassium is known to activate more than 60 plant enzyme systems and directly controls fruit size and weight, sugar content and flavor, and post-harvest shelf life. The 38% ensures your plants have consistent potassium availability during the critical fruiting period when demand peaks.

Tomatoes prefer slightly acidic conditions. For hydroponics, keep pH between 6.1-6.3 during fruiting or 6.4-6.6 during vegetative growth. For soil growing, aim for 6.2-6.5. pH directly affects nutrient availability — outside these ranges, key nutrients like iron and phosphorus become locked out even when present in the solution.

Blossom end rot is caused by calcium deficiency in developing fruit. Our formula does not contain calcium because calcium and phosphorus should not be mixed together in concentrated stock solution — combining them directly can form insoluble calcium phosphate that precipitates out and becomes unavailable to plants. That's why any high-phosphorus fertilizer should be paired with a separate calcium source applied independently.

This formula can still be part of a reduced-BER approach: the controlled nitrogen level helps limit excessive vegetative growth that could otherwise compete for available calcium, and consistent feeding keeps the plant's overall mineral balance on track. Supplement with a dedicated calcium source and maintain consistent, even watering — calcium uptake depends on steady moisture as well as availability.

Recommended calcium sources:

• Cal-Mag Plus 2-0-0 — best for hydroponic systems and container growing
• Calcium Nitrate 15.5-0-0 — water-soluble option with a small nitrogen boost
• Gypsum (Calcium Sulfate) — excellent calcium source that won't alter soil pH
• Bone Meal 3-15-0 — slow-release organic calcium and phosphorus for soil gardens

Yes. This formula is well-suited for all nightshade family plants including tomatoes (beefsteak, cherry, roma, heirloom), all pepper types (bell, hot, sweet), eggplants (standard and Asian varieties), tomatillos, and specialty crops like goji berries. It can also be used for potatoes, though potato programs often benefit from a soil test given their distinct yield and tuber-quality requirements. Larger plants like beefsteak tomatoes may need approximately 25% more fertilizer than cherry tomatoes due to their greater biomass. Note: sweet potatoes are not nightshades and have different nutritional needs — this formula is not recommended for them.

Potassium is the nutrient most directly linked to fruit quality in nightshade crops. It regulates water movement into cells (bigger fruit), drives sugar transport from leaves to fruit (better flavor), and strengthens cell walls (firmness and longevity). Our article on The Role of Potassium in Fruit Development covers this in depth with research-backed guidance.

Our fertilizer is highly hygroscopic, meaning it absorbs moisture from the air. Keep the bag sealed tight between uses and store in a cool, dry place out of direct sunlight. If it clumps from moisture exposure, simply break it up — the efficacy is not affected.

The low 4% nitrogen is intentional. During fruiting, excessive nitrogen causes lush foliage at the expense of fruit production and delays ripening. Our 4% provides just enough to maintain healthy green leaves for photosynthesis without diverting energy from fruit development. For more on nitrogen's role, read our article What's the Function of Nitrogen in Plants?

Calcium and phosphorus should not be mixed together in concentrated stock solution. Combining them directly can form insoluble calcium phosphate that precipitates out and becomes unavailable to plants. Since our formula contains 18% available phosphate (P₂O₅), calcium is best applied separately — dilute each independently before combining in the working solution. Use Cal-Mag Plus 2-0-0 or Calcium Nitrate 15.5-0-0 as a companion product.

• Manufactured in Madera, California, USA
• Tested by independent third-party laboratories for purity and guaranteed analysis
• Registered with the California Department of Food and Agriculture (CDFA)
• Independently tested for heavy metals — results consistently well below required limits
• 100% chelated micronutrients (Fe, Mn, Zn, Cu) for maximum bioavailability

If you're not completely satisfied, we offer a 90-day money-back guarantee. Simply return the unused portion in its original packaging, and we'll process a full refund. No questions asked.

We're committed to sustainable practices, including:

• Recyclable packaging materials
• Precise nutrient formulation to reduce environmental runoff
• Support for integrated pest management (IPM) practices
• Promoting efficient nutrient delivery systems like hydroponics

1% of all profits go to our foundation, focused on improving educational opportunities for children in agricultural communities.

Family-owned and operated since 1989, Greenway Biotech, Inc. has been helping growers — from backyard gardeners to commercial operations — achieve better results for over 35 years. Manufactured in Madera, California, our fertilizers are formulated with the same commitment to quality and transparency we've held since day one.