Deficiency in magnesium commonly happens if you are growing marijuana plants in a hydroponic set-up and cultivating cannabis indoors in any medium. This nutrient deficiency is not common in outdoor growing. When marijuana plants lack magnesium, their leaves will curl and will eventually die if the problem is not corrected.
The role of magnesium in a cannabis plant
Magnesium is responsible for maintaining leaf production and structure. It also plays a very important role in the breakdown of enzymes and production of chlorophyll, a green pigment that allows the marijuana plants to absorb energy from the light. Chlorophyll is very important during photosynthesis so it is also vital for the cannabis plants to receive an adequate amount of magnesium. You will know that the weed plants are getting enough magnesium if they are seen with healthy veins.
Symptoms of magnesium deficiency:
1. The leaves of marijuana plants will start to turn yellowish to brown. The only part that will remain green is the veins.
2. The leaves affected with this nutrient problem will become dry and crispy at the edges.
3. The stem and the petioles will change their color to purple.
4. The pale-green colored growing shoots will turn into whitish if magnesium deficiency is already severe.
How to resolve magnesium deficiency
To provide a solution to magnesium deficiency, add or feed your cannabis plants with Epsom salts, magnesium sulfate and other nutrients that contain magnesium and are water- soluble. Use worm castings, dolomitic lime or garden lime for an average rate of magnesium absorption. The dolomitic lime is not only used to correct magnesium deficiency but also for increasing the pH of the soil medium and other planting mixes. Since the dolomitic limestone contains a high amount of magnesium, it can be used for both purposes- to correct magnesium deficiency and for increasing the soil pH. You can also use Ca-Mg to hasten the absorption rate.
Magnesium deficiency in hydro set-up can quickly be resolved by adding one teaspoon of Epsom salts per one gallon of water. For plant mixes, you can add one teaspoon per quart of water. For the second treatment, use one-quarter dose every time you change the water reservoir. Aside from the Epsom salts, you can also use calcium-magnesium.
Magnesium deficiency is easy to diagnose and can also be corrected easily too. This type of deficiency will usually occur if you are using tap or distilled water and reverse osmosis water. Even though magnesium deficiency can easily be corrected, do not add too much Mg because it may lock up other nutrients that marijuana plants also need.