Treatment: Monitor the plant’s post feeding behaviour closely. Use one of the measures above to more accurately gauge when to water to prevent recurrence. Too much water can lead to root rot. Too little water will stunt growth. Keep a grow diary if you must and try to get into a routine as the grow progresses.
Treatment: Indoors simply turn up the heat or add more lights to the grow op and turn a negative into a bumper harvest. Outdoor growers might need to take plants inside at nighttime or at least invest in a basic DIY greenhouse.
Treatment: Make sure to hang your grow lights as per the manufacturer’s instructions. Adjust as plants progress and use a tape measure for precision. These days there are so many new grow light technologies on the market with their own nuances, you really must stick with the manufacturer’s guidelines to position the light in the sweet spot.
Indoor cannabis plants grown under artificial lights must be perfectly positioned and lamps must be in just the right distance above the canopy for best results. When lamps and reflectors are too close to the flowering tops, buds and leaves will be yellow and brown as the light is too intense. This is very much a top down problem.
The following is not a definitive list of the causes for chlorosis. It is such a common symptom, that sick plants display, we could write a book, but not today. That being said, we have focused on the most common causes for yellow leaves based on first hand pro grower experiences. If you are presently troubleshooting for a solution to chlorosis, read the next few sections carefully. Your crop could be riding on it.
Soil growers have the advantage of cultivating in a medium, that acts as a buffer for roots. Hydroponics and coco are not quite as forgiving to pH imbalances. Even soil growers need to at least come close to getting the ideal pH of 6.0-7.0 and maintain it, otherwise plants will suffer. 5.5 to 6.5 pH is generally agreed upon as the recommended range for hydro and coco. Yellow leaves can be a warning sign, that you don’t have your nutes dialled in and the pH is off.
Treatment: Invest in a pH pen or cannabis fertilisers with pH-perfect solutions, that can auto adjust a wider pH range. Flush plants with pure water and then resume feeding with a light dialled in solution to suit your growing medium. Also, make sure that the base nutrients you use contain all of the essential microelements or you will have to add extra bottles of supplements to the budget.
Cannabis plants will only thrive with an effective wet-dry cycle. This means you must water the right amount at the right time, with every watering. So what’s the best way to tell if your marijuana is thirsty? Lift up the containers when they are dry. Then again after watering, so you will know the difference.
Treatment: Indoor growers need to turn up the air conditioning and ensure intake and outtake fans are powerful enough for the size of the grow room. Again, we strongly advise consulting the fan manufacturer’s website for performance specifications. Outdoors the best growers can do is construct a simple shade and hope the heatwave is short-lived.
Are you seeing yellow leaves in your cannabis garden but can’t figure out the cause? This blog just might save your marijuana.
Note: During the last few weeks before harvest, marijuana plants start pulling all the remaining nitrogen from her leaves as part of the bud-making process. This causes yellowing leaves starting towards the bottom of the plant. This is part of the natural flowering process and you don’t need to fight it. You may notice that marijuana leaves are yellowing in almost all pictures of marijuana plants with big buds that are close to harvest. You tend to get smaller yields from nitrogen-toxic plants with dark green leaves at harvest.
If new leaves aren’t getting enough nitrogen, the plant will start to “steal” nitrogen from the older, lower leaves, so that it can give it to newer leaves. This is what causes the yellowing and wilting of a nitrogen deficiency.
Nitrogen is a mobile nutrient, which means it can move throughout the plant as needed. Cannabis needs nitrogen to keep leaves green and make energy from light. All new leaves get plenty of nitrogen to make them green and help with photosynthesis. The leaves that get the most light are the newest, youngest leaves, so the plant “wants” to give those leaves priority for getting light.
It’s extra important to find a nutrient system with lower levels of nitrogen for the last part of your plant’s life. Many “Bloom” or “Flowering” style base nutrients are just the ticket.
Remember: It’s Normal For Marijuana Leaves To Start Turning Yellow As Harvest Time Approaches
This picture shows a Nitrogen Toxicity
More About Nitrogen and Your Marijuana Plants
Most complete plant foods that you get at a gardening store contain high levels of nitrogen (N). These nutrient system tend to work well in the vegetative stage.
Example of cannabis Nitrogen deficiency – yellow bottom leaves. Almost all plant nutrients contain Nitrogen
A nitrogen deficiency causes the lower/older leaves of a cannabis plant to start yellowing, wilting, and dropping off on their own. Learn how to fix it.