• Wear gloves and safety glasses when handling large quantities
• Use a dust mask when applying in dry, windy conditions to avoid inhaling fine particles
• Wash hands thoroughly with soap and water after handling
• Change clothes if heavily soiled with product dust

• Store in a cool, dry place in the original sealed bag or container
• Keep away from direct sunlight and excessive moisture—gypsum can clump when exposed to humidity
• Store away from children and pets
• Do not store near concentrated acids

• Gypsum carries no burn risk to plants at recommended rates
• Avoid inhaling dust during spreading—use a spreader or apply when wind is calm
• Do not apply to waterways or storm drains
• Compatible with most fertilizers and amendments; no known adverse mixing reactions

• Eye contact: Flush with clean water for 15 minutes. Seek medical attention if irritation persists.
• Skin contact: Wash affected area with soap and water. Generally causes no irritation at normal handling.
• Ingestion: Do not induce vomiting. Contact Poison Control (1-800-222-1222) or seek medical attention if large amounts are swallowed.
• Inhalation: Move to fresh air. Seek medical attention if respiratory symptoms persist.

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

No. Gypsum (calcium sulfate dihydrate) is pH neutral and does not raise or lower soil pH. This is the key difference from lime (calcium carbonate), which raises pH as it dissolves. If your soil is already at or above pH 7.0 and you need calcium, gypsum is the correct choice. For acidic soils that need both calcium and pH correction, consider Dolomite Lime instead.

For general maintenance on clay soils, once per year is typical. Sandy soils may only need an application every 2–3 years. For sodic soil reclamation, multiple applications are often needed based on the severity of sodium levels—soil retesting after 6 months will guide subsequent applications. For crops like peanuts or tomatoes with high calcium demand, apply at each planting cycle.

Both provide calcium, but they work differently. Lime (calcium carbonate) raises soil pH as it releases calcium—useful for acidic soils. Gypsum (calcium sulfate) releases calcium without changing pH. Additionally, gypsum contains 18% sulfur, improves clay soil structure through flocculation, and is one of the most widely used practical amendments for reclaiming sodic soils. Use lime to raise pH; use gypsum when pH is fine but calcium, sulfur, drainage, or sodium are the issues. For a deeper look at soil pH management, see our article on Understanding Soil pH and Nutrient Availability.

Yes—this is one of gypsum's primary applications. Clay particles carry a negative charge and naturally repel each other, which compacts the soil and limits water movement. Calcium ions from gypsum bridge these charges and cause clay particles to clump together (flocculate), creating larger pore spaces for air and water. Improvements in infiltration and workability may begin within weeks under suitable moisture and soil conditions, with continued structural improvements developing over months. For more on improving clay soils, see our article on Improving Clay Soil for Better Gardens.

Mined gypsum is generally allowed in many certified organic systems, subject to certifier review. It is a natural mineral without synthetic additives, and it does not contain pesticides or heavy metal contaminants at levels of concern. Always verify specific allowed materials with your certifying agency to ensure compliance with your organic certification requirements.

Blossom end rot in tomatoes, peppers, and squash is associated with localized calcium deficiency in developing fruit tissue. Contributing factors include low available soil calcium, irregular irrigation, root stress, and excessive ammonium nitrogen. Gypsum supplies readily available calcium to the root zone, helping reduce the risk when low available calcium is part of the problem. Consistent, even irrigation and balanced fertilization remain equally important for prevention.

Yes. Gypsum is compatible with NPK fertilizers, organic amendments, and most pesticides. It can be applied simultaneously with other products or as part of a standard amendment program. The calcium from gypsum may improve the uptake of several other nutrients, including potassium and magnesium, by improving root zone conditions.

• Packaged in our FDA-registered facility in Madera, California
• Sourced to agricultural quality standards and tested for compliance with applicable safety requirements
• CDFA registered agricultural fertilizer
• Mined from high-purity natural deposits to agricultural specifications

90-day money-back guarantee. Not satisfied? Return the unused portion in its original packaging for a full refund—no questions asked.

• Responsibly sourced from natural mineral deposits with minimal processing
• Improves water infiltration, reducing agricultural runoff and erosion
• Supports sustainable soil management by reducing compaction and sodium buildup
• Helps protect water quality by reducing surface runoff from heavy clay soils

1% of all profits go to our foundation focused on improving educational opportunities for children. Learn more at greenway.foundation.

Family-owned since 1989. For over 35 years we've been making premium-grade fertilizers, soil amendments, and micronutrients that home gardeners and commercial growers trust. Made in Madera, California.