Vegetative Stage – higher levels of Nitrogen (pretty much any plant food will do) 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. Some examples of cannabis-friendly one-part Vegetative nutrient systems… Pretty much any complete plant food.
Flowering Stage – lower levels of Nitrogen (use “Bloom” or Cactus nutrients) 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. Some examples of good one-part Flowering nutrient systems… If you can’t order online and can’t find a good one-part base Bloom formula locally, you do have other choices. Though not an ideal choice, most Cactus plant foods will contain good nutrient ratios for growing cannabis during the budding stage. So in a pinch, you can use the cactus nutrients that can be found at most gardening stores. The first cannabis plant pictured below is showing signs of nitrogen deficiency late in flowering; nitrogen deficiency in late flowering is completely normal and even desired.
The last picture is an infographic about nitrogen and your marijuana plant. It’s normal for plants to show signs of a nitrogen deficiency as the plant gets close to harvest. Too much nitrogen can actually prevent proper budding, and can reduce the overall taste and smell of your plant. This is why all “bloom” and flowering nutrient formulas are relatively low in nitrogen. It’s normal to see a few Nitrogen-deficient leaves in the flowering stage. Nothing to worry about unless you see the yellowing leaves start climbing up the plant. So don’t sweat it if you see your cannabis show some signs of nitrogen deficiency late in the flowering stage! Relatively low levels of nitrogen in the late flowering stage help promote proper cannabis bud development and will increase your yields! Solution: You can find many pre-mixed nutrients from the store which contain nitrogen or you could use nitrate of soda or organic fertilizer which are both good sources of nitrogen. In fact almost all plant nutrients of any kind will include nitrogen. If you haven’t been providing any nutrient to your plants, try supplementing your regular nutrients with a bit more nitrogen and see if the plant starts recovering. If you’ve already been using nutrients, then you probably don’t have a nitrogen deficiency. If you’re seeing the signs of spreading nitrogen deficiency even a week or two giving nitrogen to your plants through nutrients, then you need to figure out what else is causing the yellowing so you can stop it. Sometimes you can get the signs of a cannabis nitrogen deficiency if the pH at the plant root zone is too low , even if the nitrogen is there. This is because when the pH at the roots is not right, your plant roots can’t properly absorb nutrients. If you aren’t sure about your root pH, learn more about pH & growing cannabis plants here. Nitrogen is especially important during the vegetative stage of your cannabis plants. As your plants start flowering, they will need lower amounts of nitrogen. Nitrogen is one of the 3 nutrients that is included in almost every kind of plant food. When looking at plant nutrients, you’ll almost always see 3 numbers listed, like 3-12-6 or 5-10-5. These numbers represent the percentage of Nitrogen (N), Phosphorous (P) and Potassium (K) contained in the bottle. Just about all plant life on Earth needs these 3 elements to grow. The 3 numbers on the front of plant nutrient bottles list the amount of Nitrogen, Phosphorus, and Potassium. The very first number, “3” in the case of the picture to the right, always displays the proportion of nitrogen in this nutrient bottle compared to the other 2 nutrients (Phosphorus and Potassium respectively). Nitrogen is in all plant nutrient formulations because it’s vital to plant processes. 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. Remember: It’s Normal For Marijuana Leaves To Start Turning Yellow As Harvest Time Approaches. Occassionally a nitrogen toxicity is mistake for a deficiency.
(pictured below) This picture shows a Nitrogen Toxicity. You can use our tool to filter by symptom and help diagnose your plant. Are some or all of your cannabis leaves turning yellow?