---
product_id: 716738850
title: "Calcium, Magnesium and Iron Supplement – Hydroponic Supplies – Liquid Nutrient Fertilizer – Supports Vegetative and Flowering Stage – 1 Quart"
brand: "humboldts secret"
price: "€ 133.47"
currency: EUR
in_stock: true
reviews_count: 5
category: "Humboldts Secret"
url: https://www.desertcart.hr/products/716738850-calcium-magnesium-and-iron-supplement-hydroponic-supplies-liquid-nutrient-fertilizer
store_origin: HR
region: Croatia
---

# Boosts nutrient uptake & absorption Optimized for hydroponics & coco coir Precise Cal-Mag-Iron balance Calcium, Magnesium and Iron Supplement – Hydroponic Supplies – Liquid Nutrient Fertilizer – Supports Vegetative and Flowering Stage – 1 Quart

**Brand:** humboldts secret
**Price:** € 133.47
**Availability:** ✅ In Stock

## Summary

> 🌱 Unlock your plants’ secret weapon for unstoppable growth!

## Quick Answers

- **What is this?** Calcium, Magnesium and Iron Supplement – Hydroponic Supplies – Liquid Nutrient Fertilizer – Supports Vegetative and Flowering Stage – 1 Quart by humboldts secret
- **How much does it cost?** € 133.47 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/716738850-calcium-magnesium-and-iron-supplement-hydroponic-supplies-liquid-nutrient-fertilizer)

## 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

- • **Deficiency Corrector:** Targets and remedies common plant nutrient deficiencies for healthier yields
- • **Hydroponic & Soil Ready:** Perfectly formulated for hydroponics, soil, container gardens & coco coir mediums
- • **Micronutrient Powerhouse:** Delivers essential calcium, magnesium & chelated iron for vibrant growth
- • **Maximized Nutrient Absorption:** Enhances uptake of minerals to fuel lush vegetative and flowering stages
- • **Proprietary Trace Mineral Blend:** Fortified to prevent blossom end rot and tip burn, boosting fruit & flower quality

## Overview

Humboldts Secret Calcium, Magnesium and Iron Supplement is a liquid nutrient fertilizer expertly crafted to correct micronutrient deficiencies in hydroponic and soil-grown plants. Its precise formula supports all growth stages, especially vegetative and flowering, by enhancing nutrient uptake and preventing common issues like blossom end rot and tip burn. Ideal for coco coir and reverse osmosis water setups, this 1-quart supplement ensures stronger, healthier plants and maximized yields.

## Description

CalMag & Iron is a specialized calcium, magnesium & iron, plant supplement designed to compensate for deficiencies in some commercial and hydroponic nutrient programs. CalMag & Iron also compensates for the natural calcium draw of coco coir fiber. CalMag & Iron provides a precise balance and optimal ratios of the calcium, magnesium and iron that are critical throughout all stages of growth, especially in heavily fruiting plants and fast blooming annuals. CalMag & Iron is fortified with a proprietary blend of select trace minerals to help maximize yields in fruiting and flowering plant varieties, prevent blossom end rot in tomatoes and peppers and reduce tip burn in lettuce. When used in combination with nutrient solutions CalMag & Iron functions as a catalyst to increase the uptake of essential minerals.

Review: Had some confusing instructions but their customer service got back to me quickly and cleared confusion. The jug arrived with no leak, has no order and my house plants are happy to get the dose of this fertilizer, especially my old lemon tree which goes out in summer and come in for winter. I notice when plants are healthy not many bugs appear. as it takes very little per gallon of water, it's a good value for the price.
Review: Perfect!

## Features

- SOURCE OF CALCIUM MAGNESIUM & CHELATED IRON: Many varieties of flowering plants require higher levels of these micronutrients. Our well-balanced formula is designed to specifically address any plant deficiencies that may be present.
- CORRECTS COMMON PLANT DEFICIENCIES: Sometimes an unhealthy plant may be suffering from a nutrient deficiency or even too much of one nutrient. Our CalMag & Iron supplement effectively corrects and remedies these micronutrient plant deficiencies.
- NUTRIENT UPTAKE AND ABSORPTION: This formulae efficiently supports nutrient uptake and absorption by addressing any plant deficiencies in the first place, thus successfully supporting the vegetative and flowering stage of your plants.
- SUITABLE FOR HYDROPONICS, SOIL, AND CONTAINER GARDENS: Nutrient systems and supplements are commonly used as hydroponic supplies and are a good solution for soil and container gardens, ensuring strong and healthy plants and yields.
- OPTIMAL FOR COCO COIR MEDIUM AND REVERSE OSMOSIS WATER: Our supplemental CalMag & Iron by Humboldts Secret is highly recommended for plants growing in coco substrate or reverse osmosis water, as the absorption process becomes magnified.

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B01GB23TEY |
| Brand Name | Humboldts Secret |
| Coverage | Medium |
| Customer Reviews | 4.6 4.6 out of 5 stars (1,540) |
| 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 |
| Part Number | TUEEQE-09 |
| Specific Uses For Product | Hydroponic |
| Target Species | Plants |
| UPC | 648260730390 |
| Unit Count | 32 Milliliters |

## Product Details

- **Brand:** Humboldts Secret
- **Item form:** Liquid
- **Liquid volume:** 32 Fluid Ounces
- **Manufacturer:** Humboldts Secret
- **Specific uses for product:** Hydroponic

## Images

![Calcium, Magnesium and Iron Supplement – Hydroponic Supplies – Liquid Nutrient Fertilizer – Supports Vegetative and Flowering Stage – 1 Quart - Image 1](https://m.media-amazon.com/images/I/71U35ykO4YL.jpg)

## Available Options

This product comes in different **Size** options.

## Customer Reviews

### ⭐⭐⭐⭐⭐ Review
*by K***O on 3 January 2026*

Had some confusing instructions but their customer service got back to me quickly and cleared confusion. The jug arrived with no leak, has no order and my house plants are happy to get the dose of this fertilizer, especially my old lemon tree which goes out in summer and come in for winter. I notice when plants are healthy not many bugs appear. as it takes very little per gallon of water, it's a good value for the price.

### ⭐⭐⭐⭐⭐ Review
*by L***� on 4 March 2026*

Perfect!

### ⭐⭐⭐⭐⭐ Review
*by A***R on 22 March 2026*

Works like a charm

## Frequently Bought Together

- Humboldts Secret Calcium, Magnesium and Iron Supplement – Hydroponic Supplies – Liquid Nutrient Fertilizer – Supports Vegetative and Flowering Stage – 1 Quart
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- 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

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**Shop now:** [https://www.desertcart.hr/products/716738850-calcium-magnesium-and-iron-supplement-hydroponic-supplies-liquid-nutrient-fertilizer](https://www.desertcart.hr/products/716738850-calcium-magnesium-and-iron-supplement-hydroponic-supplies-liquid-nutrient-fertilizer)

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*Product available on Desertcart Croatia*
*Store origin: HR*
*Last updated: 2026-07-23*