Yes, Epsom salt hydroponics works great as a magnesium and sulfur supplement for your plants. It dissolves fast in water and roots absorb it well. Many growers keep a bag on hand to fix deficiencies or boost their nutrient mix.
I used Epsom salt to save my tomato plants last summer. The older leaves showed yellow patches between the veins while the veins stayed green. This classic magnesium deficiency sign appeared on day 40 of my grow cycle.
After adding Epsom salt at 1 teaspoon per gallon, new growth came in healthy within 5-7 days. The damaged leaves never fully recovered but the plant bounced back strong. I kept using Epsom salt for the rest of that grow with great results.
The chemical name for Epsom salt is magnesium sulfate. Magnesium sulfate hydroponics works because both elements come in forms plants use right away. Magnesium builds chlorophyll in leaves. Sulfur helps make proteins.
The Epsom salt dosage plants need ranges from 1-2 teaspoons per gallon or about 1.25-2.5 grams per liter. Start at the low end and watch your plants for a week. You can add more if symptoms persist or plants still look pale.
As a hydroponic magnesium supplement, Epsom salt costs far less than fancy branded products. A bag from the drug store gives you months of supply for just a few dollars. The formula is the same as what you find in pricey hydroponic stores.
Watch out for sulfur buildup if you use Epsom salt for too long. Most nutrient mixes have sulfur in them already. Too much sulfur can throw off your nutrient balance and cause other problems down the line.
You can spot magnesium deficiency by looking at your older leaves first. The yellowing starts between the veins while the veins stay green. This differs from nitrogen issues where the whole leaf turns yellow from the bottom up.
When I first started growing, I confused magnesium issues with nitrogen problems. Adding more nitrogen did nothing at all. Once I learned to read the leaf patterns right, Epsom salt fixed things within a week. Learning this saved me lots of time.
Other magnesium sources work too if you prefer not to add extra sulfur. Magnesium nitrate gives you nitrogen as well. Magnesium chelate stays stable across a wider pH range. Each has trade offs to think about for your setup.
Always dissolve Epsom salt in water before adding it to your reservoir. Dumping dry crystals can create hot spots that burn roots. Mix it in a separate container first until it dissolves. Then pour the solution into your main tank.
Check your EC after adding Epsom salt since it raises the total reading. A teaspoon per gallon adds roughly 0.1-0.2 EC to your solution. Factor this in when you mix your base nutrients so you don't go too high.
A friend of mine adds Epsom salt to every batch of nutrients as a default. His tomatoes grow huge and produce heavy yields. He swears by half a teaspoon per gallon added right from the start of each grow cycle.
Read the full article: Hydroponic Nutrient Solutions: The Complete Guide
