Epsom Salt for Plants — Magnesium Sulfate for Gardens & Lawns
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Greenway Biotech · Family-owned in California since 1989
Epsom Salt for Plants.
Magnesium and sulfur where they are short.
Magnesium sulfate heptahydrate (MgSO₄·7H₂O): about 9.8% magnesium and 13% sulfur by weight. It dissolves completely in water for foliar sprays, soil applications, transplant drenches, lawns and nutrient solutions. Use it where a soil test, a leaf test or the plant itself points to low magnesium.
See the rates → Find your sizeShips from California · 90-day satisfaction guarantee · Free shipping over $100
~9.8%
Elemental magnesium by weight
~13%
Elemental sulfur by weight
3lb
Per 1,250 sq ft of lawn
35+yrs
Family-owned in California
01 / Choose your size
Sized by the area
you need to cover.
Lawn coverage below is one application at 3 lb per 1,250 sq ft. Garden beds and containers use far less: a tablespoon per gallon of spray, or a tablespoon per foot of plant height.
| Size | Lawn coverage, one application | Good for |
|---|---|---|
| 1 lb | ~400 sq ft | Containers, houseplants, a few beds |
| 3 lb | 1,250 sq ft | A vegetable garden for a season |
| 5 lb | ~2,100 sq ft | Home gardens |
| 10 lb | ~4,200 sq ft | Larger gardens or a small lawn |
| 20 lb | ~8,300 sq ft | Lawns and orchards |
| 25 lb | ~10,400 sq ft | Lawns |
| 2 × 25 lb | ~20,800 sq ft | Large lawns, two applications, or growers |
| Product Type | Magnesium and sulfur source for plants, lawns and nutrient solutions |
|---|---|
| Sizes | 1, 3, 5, 10, 20 and 25 lb bags, or two 25 lb bags |
| Ingredient | Magnesium Sulfate Heptahydrate (MgSO₄·7H₂O) |
| Magnesium (Mg) | ~9.8% by weight |
| Sulfur (S) | ~13% by weight |
| Source / Origin | Sourced within the United States; repackaged in Madera, California |
| Grade | USP-grade raw material, per the producer’s Certificate of Analysis, repackaged without changes |
| Solubility | ~710 g/L in water at 20 °C; dissolves completely |
| Methods | Foliar spray, soil application, transplant drench, lawn broadcast, nutrient solutions |
| Shelf Life | Indefinite when stored sealed in a cool, dry place |
02 / Ideal for
One mineral.
Five ways to apply it.
Magnesium-hungry crops respond when the soil is genuinely short: tomatoes, peppers, roses, potatoes, citrus and leafy greens most often. Healthy plants in balanced soil do not benefit from extra magnesium.
Foliar Spray
1 tablespoon per gallon of water, sprayed on the leaves every 2 weeks during the growing season. Spray early in the morning or in the evening, not in midday heat.
Soil Application
1 tablespoon per foot of plant height, worked into the soil around the base and watered in, monthly during the growing season.
Transplants
1 tablespoon per gallon of water as a drench at planting.
Lawns
3 lb per 1,250 sq ft with a broadcast spreader in spring and fall, then water in thoroughly.
Hydroponics & Fertigation
A common magnesium and sulfur source in nutrient recipes built from single salts. Your recipe or water test sets the amount.
03 / Rates
Pick your method.
Get the amount.
Apply only where magnesium is low. The calculator in the next section works out amounts for your sprayer, plants or lawn.
Quick answer: 1 tablespoon per gallon as a foliar spray every two weeks, on plants showing magnesium deficiency (yellowing between the leaf veins while the veins stay green, usually on older leaves first).
| Method | Amount | Frequency | Notes |
|---|---|---|---|
| Foliar spray | 1 tbsp per gallon | Every 2 weeks | Apply early morning or evening; avoid midday heat |
| Soil application | 1 tbsp per foot of plant height | Monthly during the growing season | Work into the soil around the base; water in thoroughly |
| Transplant drench | 1 tbsp per gallon | At planting | Water the transplant in with the solution |
| Lawn | 3 lb per 1,250 sq ft | Spring and fall | Broadcast spread, then water in thoroughly |
Apply only when needed: healthy plants in balanced soil don't benefit from added magnesium, and excess can interfere with calcium uptake. Keep calcium to magnesium at roughly 3 to 1. For the full background, see How to Really Boost Your Garden with Epsom Salt and What Is the Best Magnesium Fertilizer?
04 / Directions
Measure.
Dissolve.
Apply.
Use the calculator for your sprayer size, plant count or lawn area.
-
01
Confirm magnesium is the problem
Magnesium deficiency shows as yellowing between the veins of older, lower leaves while the veins stay green. A soil or leaf test is the surest check, and your local extension office can help.
-
02
Measure and dissolve
For sprays and drenches, stir the measured amount into water until it is fully dissolved. For soil and lawn use, apply it dry and water it in.
-
03
Apply at the right time
Spray leaves early in the morning or in the evening. Work soil applications in around the base of the plant, and broadcast lawn applications evenly.
-
04
Water in and watch
Water soil and lawn applications in thoroughly. Repeat foliar sprays every two weeks and soil applications monthly only while the plants still need it.
Keep out of reach of children and pets. Wash hands after handling.
05 / Compare
Other magnesium sources.
Different jobs.
Epsom salt adds magnesium and sulfur and nothing else. Pick another source when you also need nitrogen, potassium, calcium or a pH change.
| Product | Also supplies | Best for |
|---|---|---|
| Epsom Salt for Plants (this product) | Sulfur (~13%) | Correcting magnesium alone; fast foliar sprays |
| Magnesium Nitrate 11-0-0 | Nitrogen | Nutrient solutions where extra nitrogen is wanted |
| Sulfate of Potash Magnesia (K-Mag) | Potassium and sulfur | Soils short on both potassium and magnesium |
| Cal-Mag Plus | Calcium, a little nitrogen | Coco, RO water and hydroponic feeds that need both |
| Dolomite Lime | Calcium; raises soil pH | Acidic soils that need lime and magnesium; slower acting |
06 / Decision
Is Epsom salt the right
magnesium for your plants?
Honest sorting. Epsom salt does one job well.
A Great Fit If You
- Have plants showing magnesium deficiency, or a soil or leaf test that confirms it
- Grow magnesium-hungry crops such as tomatoes, peppers, roses, potatoes or citrus
- Want a fully soluble source for foliar sprays or nutrient solutions
- Need magnesium without adding nitrogen, potassium or calcium
Consider Another Option If
- Your soil already has enough magnesium: more can hold back calcium uptake
- Your soil is acidic and needs lime as well: try Dolomite Lime
- You also need potassium: try K-Mag
- You want Epsom salt for the bath: see Epsom Salt USP Grade, which has the bath directions
07 / Safety & handling
Read this before
you mix.
Magnesium sulfate is mild to handle. A few notes on gloves, storage, overuse and first aid.
- Handling: Wear gloves for bulk pouring and mixing to prevent skin drying, and avoid breathing dust: open and pour in a ventilated area. Wash hands after use. Not for ingestion.
- Don't overapply: Use it only where magnesium is low. Excess magnesium can interfere with calcium uptake and worsen high-salt soils. Your local agricultural extension office can help with a soil test.
- Storage: Magnesium sulfate absorbs moisture from the air and can clump. Store it sealed in a cool, dry place, away from children and pets. It keeps indefinitely when stored properly.
- First aid: Eyes: flush with clean water for 15 minutes; seek medical attention if irritation persists. Skin: rinse with water. Swallowed: do not induce vomiting; contact a healthcare provider or Poison Control (1-800-222-1222). Dust inhaled: move to fresh air; seek medical attention if symptoms persist.
08 / FAQ
Common questions.
Honest answers.
If your question isn't here, contact our team at questions@greenwaybiotech.com.
How much Epsom salt do I mix per gallon for a foliar spray?
1 tablespoon per gallon of water, sprayed on the leaves every two weeks during the growing season. Spray early in the morning or in the evening, not in midday heat.
Which plants respond to Epsom salt?
Magnesium-hungry crops respond most often when the soil is genuinely short: tomatoes, peppers, roses, potatoes, citrus and leafy greens. Healthy plants in balanced soil don't benefit from added magnesium.
Will Epsom salt fix yellow leaves?
Only when magnesium is the cause. Magnesium deficiency shows as yellowing between the veins of older, lower leaves while the veins stay green. Yellowing that starts on the newest leaves more often points to iron, and even yellowing of older leaves, veins included, to nitrogen. A soil or leaf test is the surest check.
How do I use Epsom salt on a lawn?
Apply 3 lb per 1,250 sq ft with a broadcast spreader in spring and fall, then water it in thoroughly. Use it only where the lawn shows signs of low magnesium, such as yellowing that doesn't respond to nitrogen.
Can I use it in hydroponics?
Yes. Magnesium sulfate dissolves completely and is a common magnesium and sulfur source in nutrient recipes built from single salts. Your recipe or water test sets the amount.
Is this the same as your bath Epsom salt?
It is the same USP-grade magnesium sulfate, sold here with garden and lawn directions. For bath and foot soak directions, see Epsom Salt USP Grade.
How much magnesium and sulfur does it supply?
Magnesium sulfate heptahydrate (MgSO₄·7H₂O) is about 9.86% magnesium and 13.0% sulfur by weight. A pound (453.6 g) supplies roughly 44.7 g of magnesium and 59 g of sulfur.
Does Epsom salt expire?
No. It is a stable mineral with an indefinite shelf life. Keep it sealed in a cool, dry place so it doesn't absorb moisture and clump.
Ready to start?
Pick your size. We'll ship it from California.
From a 1 lb bag for containers up to two 25 lb bags for lawns. Free shipping on orders over $100 in the continental US, and our 90-day satisfaction guarantee on every bag.
Choose your size →Ships from California · 90-day satisfaction guarantee · Documents on request
