What it is
It's short on magnesium (mg). Magnesium sits at the center of every chlorophyll molecule: without it, the leaf can't be green or photosynthesize well.
How to tell
The lower or middle leaves turn yellow between the veins, and the veins stay green: it looks like a fishbone pattern. Then brown spots appear and the leaves dry out. It's mobile, so it starts on the old leaves.
What to do
Cal-mag in the water, or magnesium sulfate (the epsom salt from the pharmacy). Sprayed on the leaves it works faster. Like calcium, it's often a lockout from pH or from excess potassium.
▲ Pros
- If you fix it early it hardly shows at harvest
▼ Cons
- Unfixed it lowers grams and quality
🎮 Practice it in UnderGrow
Same as calcium: more after overwatering, with stress and with high pH. Cal-mag fixes it.
▶ Play free