Today I’ll break down the 10 most common reasons your weed leaves turn yellow, and I’ll show you how to make your plant green again! When Not to Worry (Pictures of Normal Yellow Leaves) 10 Causes of Yellow Leaves (From Most to Least Common) 1.) PH is Too High or Low at the Roots. Whether you’re growing in soil, coco coir or in hydroponics, probably the most common reason to see yellowing and other nutrient deficiencies is the pH near the roots is too high or too low. Cannabis plants have a difficult time absorbing nutrients when the pH is off, resulting in nutrient deficiencies even if the nutrients are actually present near the roots. Yellow or other oddly colored leaves Spots, stripes or patches Burning around the edges of leaves In fact, basically any nutrient deficiency can be triggered by incorrect pH!
Growers who don’t make sure their pH stays in the right range will often run into nutrient deficiencies, even if they’re starting with a pure source of water and good soil! Soil Optimum: 6-7 pH Coco / Hydro Optimum: 5.5-6.5 pH. Use a kit or PH Pen to test the pH of water before you give it to your plants, and adjust if necessary by adding an acid or base to your water Learn How to Fix Incorrect pH. These symptoms look like nutrient deficiencies but are actually caused by incorrect pH! This is a deficiency, even though it looks a little like nutrient burn (too high levels of nutrients). The main clue is the yellow striping on the leaves.
Another clue is the brown tips are going in further than typical nutrient burn. Stripes on the leaves (click for close-up) indicates that this isn’t a Nitrogen deficiency, even though the symptoms are somewhat similar. In this case the symptoms were caused by the pH being way too high. It’s much more common to over-water than under-water cannabis plants, and the symptoms are very similar. In either case, the solution is to learn how to water your plants exactly the right amount at the right time! Droopiness (it’s normal for plants to droop a little before the lights go out, but you know the drooping is a problem if it’s already happening at the beginning of their “day”). Odd problems and symptoms from poor water practices including yellowing and sometimes other deficiencies. Overwatering – leaves seem “fat” and swollen with water. Often you’ll have a feeling you may be overwatering your plant, especially if it’s a small plant in a large container. Underwatering – leaves often seem “papery” and thin because they don’t have any water inside them. Chronic underwatering leads to overall yellowing and deficiencies. Overwatering is most common with young plants since they still have small, weak root systems You can hurt plants by giving too much or too little water at a time, and you can also cause persistent droopiness by watering too often or too infrequently Bad soil with poor drainage can cause the symptoms of overwatering even if you’re watering the plants perfectly! Small plants in big containers are easily over-watered Big plants in small containers are easily under-watered Growers who spend long periods away from their plants and/or don’t pay attention to their watering needs are much more likely to run into problems with droopiness! Start with good soil or coco coir Make sure plants are in the right size container for their size If plants start drooping after you water them, you’re overwatering! If drooping plants perk up after watering, you’re underwatering! Learn how to water your plants perfectly every time! Chronic overwatering can sometimes cause unusual deficiencies even if the pH is spot on, like this plant grown in muddy soil. The biggest sign that these symptoms are caused by overwatering and not pH (or something else) is that the plant is always droopy. Another example of a deficiency that’s actually caused by overwatering (notice how this seedling is also droopy) Chronic Underwatering (Relatively Rare) Most growers tend to overwater – not underwater – their plants. However, if you’re spending long periods away from your plants or the containers are drying up in less than a day or two, it may mean that your plant needs to be watered more often, or be given more water at a time. It’s also more common to under-water when plants start overgrowing their pots. It can be difficult to diagnose chronic underwatering because problems may look like nutrient deficiencies. Your main clue is that plants perk up every time after you water. Plants tend to be lime green or pale all over, even though the leaves appear healthy without stripes or spots Yellow leaves tend to appear towards the bottom of the plant Yellow leaves feel soft and are easily pulled off (in fact they usually fall on their own). If a leaf feels very stiff or is hard to pull out, that means it is not a Nitrogen deficiency. Affects plants which have “used up” the nutrients in the soil, which can happen after the plant has been the same container for several weeks or months.
Can happen in coco or hydro when the grower isn’t providing any extra nutrients (since there is no Nitrogen contained naturally in plain coco or water). It is very unlikely you have a true Nitrogen deficiency if you’re providing your plants with the recommended amount of cannabis nutrients in the water. Easily remedied by giving plants a regular base plant nutrient from basically any cannabis-friendly nutrient system In soil, growers can transplant their plants to a new container with fresh soil (if they don’t want to add extra nutrients in the water). This plant is on the verge of a Nitrogen deficiency. This is indicated by its overall pale color, even though all the leaves look really healthy without any spots or stripes. Cannabis leaves should not be lime green or pale, or the plant tends to grow more slowly! Here’s a close-up of a Nitrogen deficient leaf near the bottom of the plant. Nitrogen deficient leaves are soft and look/feel wilted.
If you have a Nitrogen deficiency, the yellow leaves will start falling off on their own.