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White bottle of Humboldt County's Own Magnum Magnesium and Sulfur Supplement, featuring a green creature with a gun.
Humboldt County's Own Magnum Magnesium and Sulfur Supplement, 1-gallon jug.
White jug of Humboldt County's Own Magnum Magnesium and Sulfur Supplement, with label featuring a character holding a gun.
White plastic jug with a "Magnum Magnesium and Sulfur Supplement" label.
White bottle of Humboldt County's Own Magnum Magnesium and Sulfur Supplement, featuring a green creature with a gun.
Humboldt County's Own Magnum Magnesium and Sulfur Supplement, 1-gallon jug.
White jug of Humboldt County's Own Magnum Magnesium and Sulfur Supplement, with label featuring a character holding a gun.
White plastic jug with a

Humboldt County's Own Magnum

Official Humboldt County's Own Dealer Model: ETMAG-32OZ
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 $34.99 USD
  • Delivers 5ml per gallon dose of concentrated magnesium and sulfur
  • Fortified with Vitamin B1 to mitigate plant stress during peak bloom
  • Compatible with all base nutrients and high-PK bloom boosters
  • View More Details

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THROUGH THE Cultivator's LENS Hands-On Evaluation

Who This Is For

  • You are adding a dedicated magnesium supplement because your high-PK bloom boosters are locking out essential minerals.
  • You are skipping standard Cal-Mag products because you need to fix a deficiency without adding unwanted nitrogen.
  • You are supplementing with Vitamin B1 because your high-performance feeding schedule is causing visible plant stress.

What We Found

  • We find this is the best fix for gardeners using high-PK boosters that usually cause a magnesium crash mid-season.
  • Magnum is our go-to recommendation when you need to fix a deficiency without adding unwanted nitrogen during bloom.

What Users Say

  • Users who swapped their standard Cal-Mag for this reported much greener canopies during the final weeks of flowering.
  • Gardeners running CO2 say adding this supplement kept their photosynthesis rates high enough to see a yield increase.

Humboldt County's Own Magnum

Is your garden suffering from premature yellowing or poor yields despite a heavy feeding schedule? You might be dealing with the most common cause of yield loss outside of overfeeding: Magnesium deficiency. Humboldt County's Own Magnum is a high-potency Magnesium and Sulfur supplement fortified with Vitamin B1, designed to keep your plants green, healthy, and photosynthesizing at maximum capacity. To maximize resin production while maintaining plant health, many growers combine this with Humboldt County's Own Snow Storm Ultra.

Many growers mistakenly turn to Cal-Mag products to solve these issues, but that can often make the problem worse. Most Cal-Mags contain Nitrogen (unwanted during bloom) and excess Calcium, which can actually block the transport of Magnesium within the plant. Magnum solves this by providing exactly what your plants need—Magnesium to build chlorophyll and Sulfur to support structure—without the interfering elements. Whether you are using high-PK bloom boosters like Humboldt County's Own Sonic Bloom that can sometimes lock out Magnesium or simply need insurance for high-value crops, Magnum ensures your plants maintain the chlorophyll levels necessary for optimal CO2 uptake and flower development.

Features

🧪
Pure Mg & Sulfur

Delivers essential Magnesium and Sulfur without adding unwanted Nitrogen or Calcium.

⚡
Vitamin B1 Fortified

Includes Vitamin B1 to help mitigate stress caused by high-performance bloom regimens.

🍃
Chlorophyll Production

Supplies the central Magnesium atom required for chlorophyll and photosynthesis.

🚫
Better Than Cal-Mag

Avoids the common pitfall of adding excess Calcium, which can block Magnesium uptake.

🌼
Bloom Booster Partner

Offset the Magnesium deficiencies often triggered by high Potassium/Phosphorus boosters like Humboldt County's Own Crystal Burst.

🛑
Prevents Yellowing

Targets interveinal fading and yellowing leaves to keep plants lush and productive.

What's Included

  • 1x Humboldt County's Own Magnum Bottle (Selected Size)

Specifications

Specification Value
Brand Humboldt County's Own
Nutrient Type Magnesium & Sulfur Supplement
Additives Vitamin B1
Application Rate 1 tsp (5ml) per Gallon
Application Stage Flowering / Bloom

Directions

  • Soil & Hydroponics: Use 1 tsp (5 ml) per gallon of water throughout the flowering cycle.
  • Compatibility: Works well with all popular base nutrients, including the Humboldt County's Own Deep Fusion Bloom line, and is highly recommended when using PK boosters or CO2 enrichment.

FAQ

Why shouldn't I just use a Cal-Mag product? +

Most Cal-Mag products contain Nitrogen, which is not ideal during flowering. Additionally, excess Calcium can actually block Magnesium transport within the plant, potentially worsening the deficiency you are trying to treat.

What are the signs that I need Magnum? +

The primary symptom of Magnesium deficiency is premature yellowing or interveinal fading (yellowing between the veins) of the leaves. If you see this, or if you are using strong bloom boosters, your plants likely need a Magnesium boost.

How does Magnum help with photosynthesis? +

The Magnesium atom is at the very center of the chlorophyll molecule. Without sufficient Magnesium, plants cannot produce chlorophyll, which halts photosynthesis and reduces the plant's ability to process CO2 and sunlight into energy.

Can I use Magnum with other nutrient lines? +

Yes, Magnum is compatible with all popular base nutrients. It is especially useful for those using the Humboldt County's Own Starter Pack, where high levels of Potassium in supplements can sometimes compete with Magnesium uptake.

Does Magnum contain anything besides Magnesium? +

Yes, Magnum also contains Sulfur, which is essential for plant structure and often deficient alongside Magnesium. It is also fortified with Vitamin B1 to help plants cope with stress.

Happy To Help

Questions About This Product?

Our specialists are happy to help. Call us or send a message and we'll get back to you within one business day (most of the time within a few hours.)

Call (360) 800-5535

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