If the yellowing occurs primarily at the base of the plant, the issue is likely a nutrient deficiency. The most common nutrient deficiency in cannabis is nitrogen, though note that excessive nitrogen can also cause yellowing (plus curled, claw-like leaves). If the problem is caused by a deficiency, slowly increase the concentration of your cannabis-specific fertilizer until new growth appears. If the yellowing is caused by excessive nutrients, flush the root system with pure water then add a half-dose of your fertilizer instead. Magnesium deficiency, characterized by a yellowing around the leave’s green veins, is most commonly caused by an improper pH balance. Use magnesium supplements to correct this issue
The roll of chlorophyll is to absorb sunlight and transform it into energy via a process called photosynthesis. When plants have ample access to resources, chlorophyll thrives. When plants are stressed, however, the chlorophyll begins to degrade revealing the yellow carotenoids below.
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Iron deficiency can also cause yellow leaves, though this occurs on new growth only (old leaves remain bright green). Iron deficiencies are also caused by improper pH and can be remedied with iron-fortified fertilizers. When iron is given to deficient plants, the leaves should start to turn green beginning along the edges until the whole leaf is bright green.
Wednesday January 29, 2020
Fungus gnats, which live in wet soil and feed off roots, are the most common pest in cannabis gardens. The best way to rid your garden of fungus gnats is to restrict watering until absolutely necessary (this prevents the gnats from laying eggs in the soil). A general best practice is to only water your plants when the top inch of soil is dry.
After measuring and adjusting pH, take a look at your watering schedule. The most common cause of yellow leaves is either over- or under-watering. Plants that are over-watered will have leaves that seem swollen and droopy while under-watered plants (though much less common) will be thin and frail. Poor drainage can also contribute to overwatering so always grow your cannabis in pots with drain holes.
The first thing you should do when cannabis leaves start to turn yellow is to measure the pH of your grow medium (soil, water, rice hulls, expanded clay, etc.). That’s because an improper pH balance – whether too high or too low – can actually block nutrient absorption.
Temperatures outside of the ideal range of 70 to 80 degrees Fahrenheit also risk discoloration and curl leaves. These oddities are most common in leaves toward the top of the plant and can easily be remedied with a fan (if too hot) or root insulation (if too cold). We also recommend growing plants off a cold cement or tile floor; use a milk crate or stool to raise them off the ground when necessary.
Does your cannabis grow have plants with yellow leaves? Yellowing marijuana leaves can indicate a variety of common ailments. Keep reading to learn more about cannabis plant health and tips to overcome yellow leaves.