Magnesium + Sulfur — Instant Correction
Best Epsom Salt for Plants (0-0-0 + 9.8% Mg + 13% S): Water-Soluble Magnesium & Sulfur for Chlorophyll, Flavor & Green-Up Buy on Old Cobblers Farm
When leaves turn yellow between the veins, that's magnesium deficiency — and no amount of NPK will fix it. Magnesium sulfate delivers instantly water-soluble magnesium and sulfur directly to the plant, correcting deficiency symptoms within days through foliar spray or soil drench.
Old Cobblers Farm™ Wicked Organics Magnesium Sulfate
by Organic Fertilizer — Littleton, NH
0-0-0
N-P-K Ratio
"The fastest magnesium correction available. 9.8% magnesium and 13% sulfur dissolve instantly in water for immediate uptake through leaves or roots. Corrects interveinal chlorosis, boosts chlorophyll production, and enhances flavor compounds in tomatoes, peppers, and herbs."
9.8%
Magnesium
13%
Sulfur
500 ft²
Soil Coverage / bag
4 Sizes
5, 10, 15, 20 lbs
9.8% Magnesium + 13% Sulfur
Two critical secondary nutrients in one water-soluble crystal. Magnesium drives chlorophyll production. Sulfur supports protein synthesis and flavor compound development.
Instantly Water Soluble
Dissolves completely in water for immediate availability. Foliar spray delivers magnesium directly through leaf tissue for the fastest possible deficiency correction.
Tomato & Pepper Essential
Tomatoes and peppers are heavy magnesium users. Regular Epsom salt applications prevent the interveinal yellowing that signals Mg deficiency and improve fruit flavor and yield.
Rose Grower Staple
Rose growers have used Epsom salt for decades. ½ cup per plant in spring and fall produces more basal breaks, deeper green foliage, and more vigorous cane growth.
Foliar Spray for Fast Correction
2 tablespoons per gallon sprayed on foliage delivers magnesium directly through leaf stomata. Visible greening within 3–5 days on deficient plants.
500 sq ft or 40 Gallons Per Bag
At 1 cup per 100 sq ft for soil application, one 5 lb bag covers ~500 sq ft. For liquid use, makes approximately 40 gallons of drench/spray solution.
Safe & Natural
Magnesium sulfate is a naturally occurring mineral salt. Non-toxic, organic-compatible, and safe for all plants when used at recommended rates.
Trusted by 20,000+ Growers
Developed in Littleton, New Hampshire. Sold nationwide on Amazon, Walmart, eBay, and theoldcobblersfarm.com.
| NPK Ratio | 0-0-0 |
| Item Form | Crystalline granular |
| Coverage | ~500 sq ft (soil) or ~40 gal solution per 5 lb bag |
| Category | Organic Fertilizer |
| Type | Soil Amendments |
| Sizes | 5 lb | 10 lb | 15 lb | 20 lb |
| NPK | 0-0-0 |
| Magnesium | 9.8% |
| Sulfur | 13% |
| Form | Crystalline granular (water soluble) |
| Rate | 1 cup / 100 sq ft (soil) or 2 tbsp / gal (liquid) |
| Method | Broadcast, drench, or foliar spray |
| Frequency | Every 2–4 weeks |
| Sizes | 5, 10, 15, 20 lb bags |
| Best For | Tomatoes, peppers, roses, Mg deficiency correction, chlorophyll boost |
What We Love
✓ Instantly water-soluble magnesium and sulfur
✓ Foliar spray corrects deficiency symptoms in 3–5 days
✓ Essential for tomatoes, peppers, roses, and Mg-hungry crops
✓ 500 sq ft soil coverage or 40 gallons solution per bag
✓ Natural mineral salt — organic compatible, non-toxic
Worth Noting
— Zero NPK — not a fertilizer, purely a secondary nutrient supplement
— Overuse can create magnesium-calcium imbalance — soil test first
Buy on Old Cobblers Farm →
Available in 5 lb | 10 lb | 15 lb | 20 lb
| Feature | Old Cobblers Farm™ Wicked Organics Magnesium Sulfate Old Cobblers Farm | Epsom Salt Plant Nutrient Pennington | Agricultural Grade Epsom Salt Epsoak | Epsom Salts Magnesium Sulfate Monterey | Magnesium Sulfate Epsom Salt CZ Garden Organics | Agricultural Grade Epsom Salt PowerGrow Systems | Epsom Salt (USP/Ag Grade) Greenway Biotech | 100% Magnesium Sulfate Plant Food Chemboys | Agricultural Grade Epsom Salt Epsoak | Magnesium Sulfate Epsom Salt Cz Garden | Epsom Salts Monterey | Epsom Salt Agricultural Grade Greenway Biotech | Epsom Salt Agricultural PowerGrow | 100% Magnesium Sulfate Chemboys | Organic Magnesium Sulfate Plant Food ENVY | Epsom Salt for Gardening EZ-GRO | Organic Earthworm Castings (no Epsom product) Espoma | Langbeinite 0-0-22 Down To Earth |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| NPK | 0-0-0 | Mg 9.8%, S 12.9% | 100% MgSO₄ | MgSO₄ (OMRI Listed) | 100% MgSO₄ (OMRI Listed) | 100% MgSO₄ | 100% MgSO₄ (CDFA registered) | 100% MgSO₄ (Ag Grade) | 0-0-22 | |||||||||
| Form | Crystalline granular | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
| Coverage | ~500 sq ft (soil) or ~40 gal solution per 5 lb bag | Not listed | Not listed | Not listed | Not listed | Not listed | Not listed | Not listed | Not listed | Not listed | Not listed | Not listed | Not listed | Not listed | Not listed | Not listed | Not listed | Not listed |
| Price / Size | 5 lb | 10 lb | 15 lb | 20 lb | $10–$15 / 7 lb | $33 / 18 lb | ~$15 / 4 lb | $13–$16 / 5 lb | $14 / 5 lb; $30 / 25 lb | $12–$15 / 5 lb | $13–$16 / 5 lb | $12-16 (18 lb) | $14-18 (5 lb) | $10-14 (4 lb) | $8 (1 lb), $20 (10 lb), $35 (25 lb) | $7 (1 lb), $25 (10 lb) | $12 (5 lb), $40 (50 lb) | $8-10 (1.5 lb) | $12-16 (32 oz) | — | $13 (5 lb) |
| Our Take | The fastest magnesium correction available. 9.8% magnesium and 13% ... | Epsom salt is a commodity product with standardized analysis across all brands. **Pennington dominates big-box retail.** Monterey is the main OMRI-listed branded option at garden centers. Competition is primarily on price and distribution. | Epsom salt is a commodity product with standardized analysis across all brands. **Pennington dominates big-box retail.** Monterey is the main OMRI-listed branded option at garden centers. Competition is primarily on price and distribution. | Epsom salt is a commodity product with standardized analysis across all brands. **Pennington dominates big-box retail.** Monterey is the main OMRI-listed branded option at garden centers. Competition is primarily on price and distribution. | Epsom salt is a commodity product with standardized analysis across all brands. **Pennington dominates big-box retail.** Monterey is the main OMRI-listed branded option at garden centers. Competition is primarily on price and distribution. | Epsom salt is a commodity product with standardized analysis across all brands. **Pennington dominates big-box retail.** Monterey is the main OMRI-listed branded option at garden centers. Competition is primarily on price and distribution. | Epsom salt is a commodity product with standardized analysis across all brands. **Pennington dominates big-box retail.** Monterey is the main OMRI-listed branded option at garden centers. Competition is primarily on price and distribution. | Epsom salt is a commodity product with standardized analysis across all brands. **Pennington dominates big-box retail.** Monterey is the main OMRI-listed branded option at garden centers. Competition is primarily on price and distribution. | — | — | — | — | — | — | — | — | — | — |
The Competition
Epsom Salt Plant Nutrient
by Pennington
Mg 9.8%, S 12.9%
N-P-K
Price$10–$15 / 7 lb
Epsom salt is a commodity product with standardized analysis across all brands. **Pennington dominates big-box retail.** Monterey is the main OMRI-listed branded option at garden centers. Competition is primarily on price and distribution.
Agricultural Grade Epsom Salt
by Epsoak
100% MgSO₄
N-P-K
Price$33 / 18 lb
Epsom salt is a commodity product with standardized analysis across all brands. **Pennington dominates big-box retail.** Monterey is the main OMRI-listed branded option at garden centers. Competition is primarily on price and distribution.
Epsom Salts Magnesium Sulfate
by Monterey
MgSO₄ (OMRI Listed)
N-P-K
Price~$15 / 4 lb
Epsom salt is a commodity product with standardized analysis across all brands. **Pennington dominates big-box retail.** Monterey is the main OMRI-listed branded option at garden centers. Competition is primarily on price and distribution.
Magnesium Sulfate Epsom Salt
by CZ Garden Organics
100% MgSO₄ (OMRI Listed)
N-P-K
Price$13–$16 / 5 lb
Epsom salt is a commodity product with standardized analysis across all brands. **Pennington dominates big-box retail.** Monterey is the main OMRI-listed branded option at garden centers. Competition is primarily on price and distribution.
Agricultural Grade Epsom Salt
by PowerGrow Systems
100% MgSO₄
N-P-K
Price$14 / 5 lb; $30 / 25 lb
Epsom salt is a commodity product with standardized analysis across all brands. **Pennington dominates big-box retail.** Monterey is the main OMRI-listed branded option at garden centers. Competition is primarily on price and distribution.
Epsom Salt (USP/Ag Grade)
by Greenway Biotech
100% MgSO₄ (CDFA registered)
N-P-K
Price$12–$15 / 5 lb
Epsom salt is a commodity product with standardized analysis across all brands. **Pennington dominates big-box retail.** Monterey is the main OMRI-listed branded option at garden centers. Competition is primarily on price and distribution.
100% Magnesium Sulfate Plant Food
by Chemboys
100% MgSO₄ (Ag Grade)
N-P-K
Price$13–$16 / 5 lb
Epsom salt is a commodity product with standardized analysis across all brands. **Pennington dominates big-box retail.** Monterey is the main OMRI-listed branded option at garden centers. Competition is primarily on price and distribution.
Agricultural Grade Epsom Salt
by Epsoak
N-P-K
Sizes2, 5, 18 lb
Price$12-16 (18 lb)
Ingredients100% magnesium sulfate heptahydrate; ~10% Mg, ~13% S
OrganicUSP grade, Made in USA
Magnesium Sulfate Epsom Salt
by Cz Garden
N-P-K
Sizes5 lb
Price$14-18 (5 lb)
Ingredients100% magnesium sulfate; agricultural grade, Made in USA
OrganicOMRI Listed
Epsom Salts
by Monterey
N-P-K
Sizes4 lb
Price$10-14 (4 lb)
Ingredients100% magnesium sulfate; granular, water-soluble
OrganicGarden-labeled
Epsom Salt Agricultural Grade
by Greenway Biotech
N-P-K
Sizes1, 5, 10, 20, 25, 50 lb
Price$8 (1 lb), $20 (10 lb), $35 (25 lb)
Ingredients100% magnesium sulfate heptahydrate; 9.8% Mg, 12.9% S
OrganicAgricultural grade
Epsom Salt Agricultural
by PowerGrow
N-P-K
Sizes1, 5, 10, 25, 50 lb
Price$7 (1 lb), $25 (10 lb)
Ingredients100% magnesium sulfate; pH neutral, 100% water soluble
OrganicAgricultural grade
100% Magnesium Sulfate
by Chemboys
N-P-K
Sizes1, 5, 25, 50 lb
Price$12 (5 lb), $40 (50 lb)
Ingredients100% magnesium sulfate dry pellets; ag-grade tested
OrganicAgricultural grade, Made in USA
Organic Magnesium Sulfate Plant Food
by ENVY
N-P-K
Sizes1.5 lb
Price$8-10 (1.5 lb)
IngredientsMagnesium sulfate; water-soluble epsom salts
OrganicOrganic
Epsom Salt for Gardening
by EZ-GRO
N-P-K
Sizes32 oz (liquid)
Price$12-16 (32 oz)
IngredientsLiquid magnesium sulfate concentrate; professional formulation
OrganicProfessional grade
Organic Earthworm Castings (no Epsom product)
by Espoma
N-P-K
IngredientsNote: Espoma does NOT sell Epsom salt. Gap opportunity.
Langbeinite 0-0-22
by Down To Earth
0-0-22
N-P-K
Sizes5, 25, 50 lb
Price$13 (5 lb)
IngredientsNaturally mined langbeinite (K-Mag); potassium + magnesium + sulfur in one mineral
OrganicOMRI, CDFA OIM
9.8% Magnesium + 13% Sulfur
Two critical secondary nutrients in one water-soluble crystal. Magnesium drives chlorophyll production. Sulfur supports protein synthesis and flavor compound development.
Instantly Water Soluble
Dissolves completely in water for immediate availability. Foliar spray delivers magnesium directly through leaf tissue for the fastest possible deficiency correction.
Tomato & Pepper Essential
Tomatoes and peppers are heavy magnesium users. Regular Epsom salt applications prevent the interveinal yellowing that signals Mg deficiency and improve fruit flavor and yield.
Rose Grower Staple
Rose growers have used Epsom salt for decades. ½ cup per plant in spring and fall produces more basal breaks, deeper green foliage, and more vigorous cane growth.
Common Questions
