Cannabis Nutrient Deficiencies: Diagnose and Fix Leaf Symptoms

Nitrogen is mobile. When supply runs short, the plant moves it out of older leaves to support the top. In the video, the lower canopy yellows first while newer leaves stay greener. As it progresses, that yellowing works its way up.

My fix

Once my runoff check points to a nitrogen shortage, my quick fix is FloraMicro. The bottle shown is 5-0-1, so nitrogen is its main NPK contribution. The clip below shows exactly what I use.

▶My nitrogen fix: FloraMicro2:55 to 3:12 · 17 seconds

More examples: yellow bottom leaves.

Early phosphorus symptoms can resemble calcium problems. The later pattern I look for is the dark, stain-like patching shown here. In the video, those patches spread until the affected leaves become dry and curl upward.

My fix

For an actual phosphorus shortage, Dyna-Gro is the correction I show, along with phosphate amendments as another option. Recheck the finished solution’s pH after mixing.

▶My phosphorus fix: Dyna-Gro3:44 to 3:53 · 9 seconds

Look around the outside of the leaf. The tips and edges yellow or brown first, then the damage spreads inward. In the examples I show, the center stays green longer than the margins.

My fix

The video names FloraGro or TPS Signal as quick options. For an organic potassium source, I mention langbeinite. Pick the correction that fits your feed instead of adding all three.

▶My potassium fixes4:08 to 4:17 · 9 seconds

Calcium problems can overlap visually with phosphorus and potassium. The rust-colored spotting is what I focus on here, along with checking the newer growth. Watch the close-up and the whole-plant example together.

My fix

My correction is Cal-Mag, with one important detail from the video: do not overdo it. Excess calcium can interfere with potassium uptake and create another imbalance.

▶My calcium fix: Cal-Mag4:44 to 4:52 · 8 seconds

This is one of the easiest patterns for me to recognize. The leaf starts looking striped as the tissue between the veins yellows. In the later examples, those yellow areas turn brown and the plant becomes much paler.

My fix

The product I show is plain Epsom salt, or magnesium sulfate. It supplies both magnesium and sulfur. Measure the amount for your feed volume and account for what is already in the mix.

▶My magnesium fix: Epsom salt5:08 to 5:18 · 10 seconds

The giveaway in my example is the plant’s overall lime-green appearance. Sulfur is an essential nutrient used in smaller amounts, and this clip lets you compare the whole plant with the study’s leaf progression.

My fix

Magnesium sulfate supplies sulfur too, which is why Epsom salt appears again here. Treat it as one addition supplying two nutrients, not a separate dose for each symptom.

▶My sulfur correction5:36 to 5:43 · 7 seconds

The iron example is much less dramatic than the nitrogen or magnesium examples. I point out slight visible changes, while most of the leaf remains intact. In this flowering trial, iron omission did not produce a significant drop in floral yield.

What I use

For trace-element coverage, I show Grow Big, FloraMicro and Dyna-Gro. The shared clip below explains the iron and manganese already supplied by these feeds.

▶Iron and manganese: the feeds I show6:29 to 6:46 · 17 seconds

Side by side, the manganese-omission plant and the normally fed control look very similar. That is the result worth showing here. The study found no clear visible manganese-deficiency symptoms during this trial; nutrients carried over from veg may help explain it.

What I use

My approach in the video is to cover these small trace-element needs through the base nutrients I already use. Here is the exact shared explanation, without replaying the earlier deficiencies.

▶Iron and manganese: the feeds I show6:29 to 6:46 · 17 seconds