This cannabis seedling is dark because it was underwatered in a “hot” soil mix (too much Nitrogen), but after watering the plant as normal for a week or two, the plant started growing vigorously
But cannabis plants need relatively low levels of Nitrogen in the second half of the flowering/budding stage. While your plants still need N (nitrogen) during flowering, too much N at this stage will prevent your plants from forming buds properly, resulting in lower yields, less potency and possibly inferior buds.
When it comes to nitrogen, this is what your plant needs:
Some examples of good one-part Flowering nutrient systems…
Flowering Stage – lower levels of Nitrogen (use “Bloom” or Cactus nutrients)
Your plant needs a lot of nitrogen in the vegetative stage, and it’s generally hard to give too much as long as you’re not going completely overboard with nutrients. Nitrogen is a big part of what makes leaves green, and is incredibly important to the process of photosynthesis (making energy from light).
So then what was really causing my claw leaves?
Note: During the last few weeks before harvest, marijuana plants starts 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 at harvest from nitrogen-toxic plants with dark green leaves.
- Marijuana plants that get too much Nitrogen in the vegetative stage don’t grow as vigorously.
- Too much nitrogen is especially harmful in the flowering stage, because this will cause your plant to produce much smaller buds.
- If you react quickly and reduce your nitrogen levels at the first sign of toxicity, your plant will quickly recover.
Does your plant have "the claw?" The talon-like leaves that are bent at the ends are a sign that your plant may have nitrogen toxicity. Learn how to fix it.