--- product_id: 42491759 title: "CalMag & Iron, Liquid Plant Nutrient Fertilizer, 32 Ounce | Calcium, Magnesium & Chelated Iron Formula, Prevents Nutrient Deficiencies, For Soil, Coco, Hydroponics & RO Water, Easy Mix" brand: "humboldts secret" price: "€ 69.49" currency: EUR in_stock: true reviews_count: 8 category: "Humboldts Secret" url: https://www.desertcart.hr/products/42491759-calmag-and-iron-liquid-plant-nutrient-fertilizer-32-ounce-calcium store_origin: HR region: Croatia --- # Fast-acting nutrient absorption Calcium, Magnesium & Chelated Iron blend 32 fl oz liquid formula CalMag & Iron, Liquid Plant Nutrient Fertilizer, 32 Ounce | Calcium, Magnesium & Chelated Iron Formula, Prevents Nutrient Deficiencies, For Soil, Coco, Hydroponics & RO Water, Easy Mix **Brand:** humboldts secret **Price:** € 69.49 **Availability:** βœ… In Stock ## Summary > 🌿 Unlock your garden’s secret weapon for unstoppable growth! ## Quick Answers - **What is this?** CalMag & Iron, Liquid Plant Nutrient Fertilizer, 32 Ounce | Calcium, Magnesium & Chelated Iron Formula, Prevents Nutrient Deficiencies, For Soil, Coco, Hydroponics & RO Water, Easy Mix by humboldts secret - **How much does it cost?** € 69.49 with free shipping - **Is it available?** Yes, in stock and ready to ship - **Where can I buy it?** [www.desertcart.hr](https://www.desertcart.hr/products/42491759-calmag-and-iron-liquid-plant-nutrient-fertilizer-32-ounce-calcium) ## Best For - humboldts secret enthusiasts ## Why This Product - Trusted humboldts secret brand quality - Free international shipping included - Worldwide delivery with tracking - 15-day hassle-free returns ## Key Features - β€’ **Rapid Deficiency Recovery:** Targets nutrient imbalances quickly to restore plant health and boost photosynthesis. - β€’ **Consistent Pro-Grade Formula:** Manufactured in California with trusted quality for over 10 yearsβ€”no guesswork, just results. - β€’ **Power-Packed Plant Nutrition:** Delivers essential Ca, Mg & chelated Fe for vibrant growth and rich foliage. - β€’ **Stronger Stems & Fruit Quality:** Fortifies plant structure and prevents blossom end rot for bountiful, firm harvests. - β€’ **Universal Garden Compatibility:** Optimized for soil, coco, hydroponics, and RO water setupsβ€”grow anywhere with confidence. ## Overview Humboldts Secret CalMag & Iron is a professional-grade liquid nutrient supplement delivering calcium, magnesium, and chelated iron in a fast-absorbing formula. Designed for versatile use in soil, coco coir, hydroponics, or RO water, it strengthens stems, enhances leaf color, and supports vigorous vegetative and flowering growth. Trusted by gardeners for over a decade, this 32-ounce solution prevents common deficiencies and blossom end rot, ensuring lush, healthy plants and abundant harvests across all growing environments. ## Description Simple Feeding, Better Gardens Clear directions and consistent quality, no guesswork. Trusted by Gardeners Trusted by gardeners for over 10 years. Professional-grade plant nutrition, simple and consistent, from indoor plants to outdoor gardens. Trusted by Gardeners Trusted by gardeners for over 10 years. Professional-grade plant nutrition, simple and consistent, from indoor plants to outdoor gardens. Starter Kit & Essentials Visit the Store Starter Kit & Essentials Visit the Store Plant Food & Growth Visit the Store Plant Food & Growth Plant Care & Protection Visit the Store Plant Care & Protection Soil & Water Care Visit the Store Soil & Water Care Outdoor Essentials Visit the Store Outdoor Essentials How did we get our start? Humboldts Secret was created by gardeners, for gardeners, with a simple goal, make high-quality plant nutrients affordable and easy to use, so more people can grow with confidence. What makes our products unique? Humboldts Secret products are made with carefully selected ingredients and manufactured in our California facility, for consistent quality you can count on. What problem are we solving? We make plant nutrition simpler, clearer, and easier to follow, so gardeners can spend less time guessing and more time growing. How did we get our start? Humboldts Secret was created by gardeners, for gardeners, with a simple goal, make high-quality plant nutrients affordable and easy to use, so more people can grow with confidence. What makes our products unique? Humboldts Secret products are made with carefully selected ingredients and manufactured in our California facility, for consistent quality you can count on. What problem are we solving? We make plant nutrition simpler, clearer, and easier to follow, so gardeners can spend less time guessing and more time growing. Review: Helps azaleas for chlorosis if your water is hard or alkaline . - Excellent source of trace elements as well as iron. My azaleas responded really nicely. Chlorosis disappeared in a few days and the leaves turned to deep green. I also used a bit of Epsom salts (MgSO4). Review: Great for my hydroponic garden - Great for my hydroponics! ## Features - Packaging Update: You may receive previous or updated packaging during our transition. Same formula, same performance. Strength for Every Stage - Humboldts Secret supplement with cal mag for plants delivers calcium, magnesium, and chelated iron to prevent deficiencies. It fortifies stems, improves leaf color, and supports flowering and fruiting plants for vigorous, healthy growth in any type of garden. - Fast-Acting Plant Recovery: Our balanced formula with calmag and chelated iron targets issues caused by nutrient imbalances, helping plants recover quickly. It boosts photosynthesis, nutrient transport, and root strength in vegetables, flowers, and herbs grown indoors or outdoors. - Maximum Absorption Power: Using our cal-mag for plants blend with added iron improves uptake efficiency, ensuring these essential minerals are fully utilized. It supports lush vegetative growth and abundant blooms, delivering consistent results for home or commercial growers. - Reliable Across All Setups: Humboldts Secret cal mag fertilizer with iron works in hydroponics, soil, and container gardens. It strengthens plant structure, enhances fruit quality, and ensures balanced nutrition in indoor and outdoor systems for dependable, healthy harvests. - Focused on Fruiting Success: Our formula with calcium and magnesium for plants plus chelated iron benefits crops in coco coir or reverse osmosis water. It helps prevent blossom end rot, promotes firm fruit set, and improves nutrient absorption for strong, productive plants in challenging conditions. ## Technical Specifications | Specification | Value | |---------------|-------| | ASIN | B01GB23TEY | | Best Sellers Rank | #12,195 in Patio, Lawn & Garden ( See Top 100 in Patio, Lawn & Garden ) #419 in Garden Fertilizers | | Brand | Humboldts Secret | | Brand Name | Humboldts Secret | | Coverage | Medium | | Customer Reviews | 4.6 out of 5 stars 2,054 Reviews | | Item Form | Liquid | | Liquid Volume | 32 Fluid Ounces | | Manufacturer | Humboldts Secret | | Mixing Ratio | 1-2ml:1000ml for vegetative growth and 2-5ml:1000ml for flowering | | Model Number | 15195521384514 | | Number of Items | 1 | | Number of Packs | 1 | | Part Number | TUEEQE-09 | | Specific Uses For Product | Hydroponic | | Target Species | Plants | | UPC | 648260730390 | | Unit Count | 32 Fluid Ounces | ## Product Details - **Brand:** Humboldts Secret - **Item Form:** Liquid - **Liquid Volume:** 32 Fluid Ounces - **Manufacturer:** Humboldts Secret - **Specific Uses For Product:** Hydroponic ## Images ![CalMag & Iron, Liquid Plant Nutrient Fertilizer, 32 Ounce | Calcium, Magnesium & Chelated Iron Formula, Prevents Nutrient Deficiencies, For Soil, Coco, Hydroponics & RO Water, Easy Mix - Image 1](https://m.media-amazon.com/images/I/71U35ykO4YL.jpg) ## Available Options This product comes in different **Size** options. ## Customer Reviews ### ⭐⭐⭐⭐⭐ Helps azaleas for chlorosis if your water is hard or alkaline . *by C***S on March 29, 2026* Excellent source of trace elements as well as iron. My azaleas responded really nicely. Chlorosis disappeared in a few days and the leaves turned to deep green. I also used a bit of Epsom salts (MgSO4). ### ⭐⭐⭐⭐⭐ Great for my hydroponic garden *by J***N on June 1, 2026* Great for my hydroponics! ### ⭐⭐⭐⭐⭐ This stuff WORKS!! *by J***7 on January 30, 2026* This stuff is great! My pepper plants were turning yellow and had blossom end rot so they were getting a lottlw rotten hole before they were even ready to pick. I read online that several ppl recommended this for that problem. It was like a miracle, I used it twice and my plants turned green again and the peppers started growing perfectly! I kept using them as recommended and got so many beautiful peppers from my plant all summer! Life saver! Plus it is so concentrated, you only use about a cap full with a gallon of water so it will last FOREVER! ## Frequently Bought Together - Humboldts Secret Calcium, Magnesium and Iron Supplement – Hydroponic Supplies – Liquid Nutrient Fertilizer – Supports Vegetative and Flowering Stage – 1 Quart - Humboldts Secret Sweet & Sticky – Carbohydrate and Saccharide Energy Source – Enhance Aroma and Flavor of Plants – Potting Soil for Indoor Plants – Energy for Plants – 32 Ounces - Humboldts Secret Set of A & B Liquid Hydroponics Fertilizer - World's Best Nutrient System – Hydroponic Nutrients for Outdoor, Indoor Plants – Supports Vegetative and Flowering Stages of Plants --- ## Why Shop on Desertcart? - πŸ›’ **Trusted by 1.3+ Million Shoppers** β€” Serving international shoppers since 2016 - 🌍 **Shop Globally** β€” Access 737+ million products across 21 categories - πŸ’° **No Hidden Fees** β€” All customs, duties, and taxes included in the price - πŸ”„ **15-Day Free Returns** β€” Hassle-free returns (30 days for PRO members) - πŸ”’ **Secure Payments** β€” Trusted payment options with buyer protection - ⭐ **TrustPilot Rated 4.5/5** β€” Based on 8,000+ happy customer reviews **Shop now:** [https://www.desertcart.hr/products/42491759-calmag-and-iron-liquid-plant-nutrient-fertilizer-32-ounce-calcium](https://www.desertcart.hr/products/42491759-calmag-and-iron-liquid-plant-nutrient-fertilizer-32-ounce-calcium) --- *Product available on Desertcart Croatia* *Store origin: HR* *Last updated: 2026-08-29*