Potassium is one of the three major nutrients needed by cannabis plants. Marijuana plants need potassium to move nutrients, water, and especially carbohydrates in the plant tissues. Without potassium or when this nutrient is present in small amounts, your plants won’t be able to produce food and will grow weak and sickly. Potassium deficiency cannabis is a condition where there is not enough potassium which affects plants during the growing and flowering stages.
It is very easy to spot potassium deficiency as the leaves show burnt tips or edges with yellow margins. The symptoms are present mostly in the older and bigger leaves however, there are times when these are also present in higher and younger leaves.
What Does Potassium Deficiency Cannabis Look Like?
Older leaves of cannabis plants with potassium deficiency have burnt edges but in between the burnt edge and the green part of the leaves, is a yellow border. You might notice that this symptom is similar to a plant with nutrient burn however, there is no yellow margin seen in plants with a nutrient burn.
Usually, the brown edges appear first but sometimes, the yellowing may also appear first. Experts also compare these symptoms to iron toxicity as the leaves may turn completely yellow as tips curl and turn brown. These leaves eventually dry out and die.
Sometimes, potassium deficiency can turn leaves from green to white instead of looking burnt. But no matter what color, the veins remain green
The Difference Between Potassium Deficiency and Light Burn
Take note of the distance of your plants to the grow lights. If your lamps are too close, the LEDs or HPS lamps can burn your plants causing some form of sunburn. This can happen even when the temperature is cool. Light burn can look like cannabis potassium deficiency but the actual problem is the distance of the growing lights to the leaves of your plants.
How to Solve Potassium Deficiency
Potassium deficiency must be solved right away because this nutrient is necessary for the production of large and dense buds. Potassium is necessary for the production of large and dense buds and thus, is needed more during the flowering stage.
- Ensure that you’re not dealing with a light burn or nutrient burn
This is a very crucial step as you don’t want to make costly mistakes. Identify first if your plants are suffering from light burn as there are different treatments for each condition.
Check the leaf edges; if you spot burnt edges or tips with no bright yellow borders between the burnt edges and green center parts of the leaves, then you are dealing with a nutrient burn. If you spot significant bright yellow borders between the burnt edges and green leaf part, you are dealing with potassium deficiency. Also, if you spot burnt edges and tips on older or bigger leaves then this is potassium deficiency. Most nutrient and light deficiencies may affect even the upper or younger leaves. In worst conditions, it can happen to the entire plant.
As an emergency treatment for all nutrient deficiencies, discontinue the plant food you are currently providing. Whether you’re in the middle of the growing phase or the blooming phase, stop your feeding and proceed with flushing your system with clean and ph- balanced water. Follow up with correct nutrients with the right amounts of potassium.
- Always use the right nutrients – potassium is needed by cannabis plants during the blooming phase as this nutrient can help improve bud growth, size, and yield. At this point, we recommend using commercially-prepared nutrients as these are specially formulated to produce good results. Stop using homemade compost or teas for now.
- Correct pH ASAP – incorrect pH at the roots and soil can affect the way your plants absorb potassium. If you use commercially-prepared food and yet you still notice potassium deficiency symptoms, your plants are likely suffering from pH imbalance at the roots or soil. The ideal pH for the proper absorption of potassium is 6.0 to 7.0. Values higher and lower than these will affect the absorption of nutrients including potassium. To enhance pH, flush your system with clean, pH-balanced water, and afterward, feed your plants good quality fertilizer with correct amounts of nutrients.
- Always maintain good root health – your plants feed on the roots and take in precious oxygen as well. Therefore, it’s very important to keep your roots healthy. One way is to water your plants correctly. If you’re growing weed outdoors, water your plants during the early morning as it is not too hot for your plants. This gives your plants enough time to absorb more nutrients through the uptake of water. And if you’re growing cannabis indoors, you must water only when the soil is dry and not when it’s wet or moist.
Tips on How to Avoid Potassium Deficiency in Cannabis
Potassium deficiency is avoidable. Start by growing your plants in healthy cannabis growing soil. If you must use topsoil from your garden or yard, have it tested first. Amend your soil with correct amounts of nutrients.
Water your plants correctly as overwatering and underwatering can lead to nutrient deficiencies. Always monitor pH and for any problems, act fast to correct pH problems.
Use only time-tested nutrients as these will never lead to nutrient deficiencies. Avoid nutrients, supplements, or fertilizer that are labeled “time-released” as these may not supply the correct amounts of potassium that plants need. Also, do not use an all-around product as these may not work well with cannabis plants. Remember, cannabis plants have different nutritional requirements during the vegetative phase and the flowering phase. Overlooking this fact may greatly affect your plants, health, and overall development.
Finally, avoid plant stress as stress can greatly affect the way your plants absorb nutrients. Stress can also lead to serious complications.
Potassium deficiency cannabis is preventable and treatable. But take note that the disease will not progress when correct and early treatments are provided and affected leaves will never return to their previous appearance.