Sulfur deficiencies are rather uncommon. They show up initially by yellowing the younger leaves (occasionally the leaves turn red or orange). Growth becomes slow as the leaves start to narrow and become brittle. The leaves are also small by comparison and they look mutated. During flowering, buds may die and the overall growth of the plant is limited. Veins may turn yellow and necrotic areas may appear at the leaf's base in severe cases. Woody, thin stems will get longer but not wider.
A surplus of sulfur will mitigate the size of the marijuana plant and its leaves will appear dead and brown at the tips. Excessive sulfur mimics salt damage with its limited growth and dark colors.
Root growth, the abundance of chlorophyll, and the production of plant proteins are all things that sulfur facilitates during vegetative growth.
Perhaps the easiest way to solve a sulfur deficiency is through the use of Epsom salts. Simply irrigate the plant with Epsom salts and wait for its state to improve. One or two teaspoons of Epsom salts per gallon of water should work (filially and in the irrigation water). You can also mix in any nutrients that contain sulfur. Water-soluble fertilizers that have sulfur in some concentration will also do the trick. Other options include:
- Elemental garden sulfur
- Potassium sulfate
Do not use gypsum on soil that has a pH of less than 5.5. It can produce conditions that are poisonous to the plants.