(N) Nitrogen Deficiency (N) deficiency’s are the most common issue you will encounter while cultivating cannabis especially during extended veg cycles. The symptoms will usually start at the bottom of the plant and work its way up to the top if not corrected in a timely manner, however near the end of the flowering cycle you should notice that some fan leaves are becoming nitrogen deficient and dropping off, this is completely natural and is actually a good sign that your plants are utilizing all the nutrients in the medium and are probably not locked up. Solution: Feed with a nutrient that is high in N either a bottled nutrient, tea or dry amendment. (bat guano, fish emulsion and earth worm castings are great organic ways of adding (N) back into your soil.
(P) Phosphorus Deficiency
(P) Deficiency’s normally occur about 1-2 weeks into flowering (if not given enough P during the switch between 16 and 12 hours) and are easy to spot due to the obvious yellowing that starts from the outside of the leaves and pushes inward, once the leaf is fully yellow and the deficiency has progressed you will begin to notice necrosis (brown dead patches of plant tissue) going along the main veins of the leaves.
Solution: Feed your plants a bloom nutrient that is high in P, this will correct the deficiency within a couple of days depending on the nutrients used. If a leaf has only the early stage symptoms then the leaf should return to its normal emerald green
(K) Potassium Deficiency
Potassium is an essential macro nutrient and is required for proper growth and reproduction of plants. Potassium is considered second only to nitrogen, when it comes to nutrients needed by plants. Sometimes you’ll see the symptoms of a (K) deficiency at the top of the plant. Leaves with a this deficiency become yellow, brown, or burnt around the edges and tips. The burnt edges may look a little like nutrient burn, except the affected leaves also start turning yellow in the margins.
(Mg) Magnesium Deficiency
Magnesium (Mg) is an essential micro nutrient. It has a wide range of key roles in many plant functions. One of magnesium’s well-known roles is in the photosynthesis process, as it is a building block of Chlorophyll, which makes leaves appear green. A light green or yellow coloring will begin to show on the veins and edges of the lower & older leaves – this is one of the classic signs of cannabis magnesium deficiency.
Solution: Most growers use a calcium magnesium supplement such as General Hydroponics CAL-MAG which will usually correct the issue within one week. You can also use dolomite lime in your soil in order to prevent a Mg deficiency from occurring to begin with.
(S) Sulfur Deficiency
Sulfur deficiencies in marijuana plants are quite rare. This is a good thing because good growing roots, the proper amount of chlorophyll, and the development of plant proteins are all processes aided by sulfur throughout the vegetation stage. Sulfur is essential for chlorophyll formation. It is a major constituent of one of the enzymes required for the formation of the chlorophyll molecule. -Essential in the synthesis of oils, especially in oil crops. -Active in the metabolism of nitrogen.
Symptoms: When the leaves begin to slim and become fragile, the plants growth will slow down. In contrast, the leaves will also be smaller. When in the flowering stage the buds begin to die off and the whole plants growth may slow down. If the issue is serious, the veins of the plant may become yellow and necrosis will most likely be visible on the bottom of the leaf. The slim, woody stems will continue growing taller but will not expand. Having too much sulfur will reduce the size of your plant and cause the leaves to become dead and brown on the tips. Too much sulfur has the same damaging effect as salt with reduced growth and dark colors.
(Zn) Zinc Deficiency
(Mn) Manganese Deficiency