SOP: Diagnose and fix nutrient burn (tip burn) in cannabis

Download the nutrient burn (tip burn) SOP checklist A step-by-step checklist to diagnose tip burn in coco, pH → EC → environment.

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What “nutrient burn” actually is

“Nutrient burn” is a symptom (usually burnt tips/edges, clawing, slowed growth), not a single diagnosis. The same look can come from three buckets:

1. Root zone too strong (excess salts / high EC in the medium)

2. Uptake blocked (lockout from pH, root stress, irrigation swings)

3. Environment too harsh (light/heat/low RH driving stress)

Your job is to identify which bucket is active before you change feed strength.

Tools you need (minimal)

• pH pen (calibrated)

• EC/TDS meter

• Thermometer at canopy (or IR gun)

• Way to estimate VPD (app/calculator) + RH sensor

• Optional: PPFD meter (or at least a reputable light map)

• Optional: substrate EC/pH sensor, cultivation logs

Safety rules (don’t skip)

• Change one variable at a time (otherwise you won’t know what fixed it).

• Don’t “flush” aggressively by default, especially in coco. Use “flush-lite” (increase runoff) unless you’re in severe toxicity.

• Judge recovery by new growth, not damaged leaves (old damage won’t reverse).

Mini SOP: 3-step diagnosis (the same order as your slides)

Step 1: Measure runoff pH (coco)

Target: 5.6–5.9

Sample properly: measure feed pH/EC, then collect runoff from a normal irrigation event (not a panic flush).

If runoff pH is HIGH (too alkaline, eg ~6.1+)

What it usually means: uptake is reduced and plants can look “underfed” even if you’re feeding enough.

Actions

1. Fix pH first (bring runoff back into 5.6–5.9 over the next 24–72 hours).

2. If your input/feed EC isn’t excessive, don’t cut feed yet.

3. Reassess after pH is back in range.

Do NOT

• Drop EC hard while pH is off, you can starve the plant and slow recovery.

If runoff pH is LOW (too acidic, ≤ 5.4)

Go to Step 2.

Step 2: If runoff pH is LOW (≤ 5.4), measure runoff EC (trend-based)

Don’t chase one number. Compare runoff vs input and watch the day-to-day direction.

Interpret it

• Runoff EC slightly above input can be normal.

• Runoff EC much higher than input and/or rising daily = salts building in the medium.

Actions (choose the smallest effective move)

If runoff EC is high/rising

1. Reduce feed strength one step (think 10–30%, not “nuke it”).

2. Increase runoff for a few irrigations (flush-lite): slightly larger shots or an extra event to wash salts out.

3. Keep pH in range while doing this.

If runoff EC is normal

• Don’t blame salts. Go to Step 3.

Step 3: Rule out environment + watering

This is where most “EC problems” actually live.

A) Light/heat (canopy stress)

Check

• Measure PPFD + canopy temperature at the top of the canopy.

• Symptoms often worst on top leaves, closest to the light.

Fix

• Raise/dim lights, improve canopy air mixing, reduce hotspots.

B) Low RH / high VPD (plants “drink too hard”)

Targets

• Veg: 0.8–1.2 kPa

• Flower: 1.1–1.3 kPa (safer, less argument bait)

Fix

• Increase RH (or reduce temp), smooth swings at lights-on.

C) Watering/root stress (coco specific)

What causes “burn” even when feed looks fine

• Big drybacks or inconsistent irrigation timing can spike root-zone EC between feeds.

Guidance (coco)

• Avoid big drybacks. Aim max:

• 15–25% veg

• 25–35% flower

Fix

• More consistent irrigation events, avoid extreme drybacks, stabilise runoff %.

Immediate response (when burn is actively getting worse)

Use this if you’re seeing new tips burning daily.

1. Stop changing multiple things.

2. Do the 3-step order above.

3. If Step 2 confirms salts building:

4. Reduce feed one step

5. Flush-lite (increase runoff) for 24–72 hours

6. If Step 3 confirms environment:

7. Fix light/VPD first before changing nutrition again.

Recovery expectations (what “getting better” looks like)

• Mild: 7–14 days for new growth to look clean

• Moderate: 2–4 weeks

• Severe: up to 6 weeks

Signs of recovery:

• No new burn on new growth

• Leaves regain normal posture, and growth rate stabilises

Common lookalikes (quick checks)

• Nitrogen toxicity: dark green + clawing (not classic tip burn)

• Overwatering: droop + yellow, slower growth, not crispy tips

• Light burn: top leaves paling/bleaching

• Deficiency patterns: more uniform chlorosis or interveinal yellowing vs “crispy tips”

Prevention checklist (daily/weekly habit)

Daily

• Log feed pH/EC

• Spot-check RH/temp (and VPD if possible)

• Quick top-canopy visual check

Weekly

• Compare input vs runoff pH + EC from multiple pots/areas

• Check irrigation consistency + dryback %

• Confirm PPFD/temperature at the canopy hasn’t drifted

Optional high-precision

• Leaf tissue test when symptoms persist despite correct pH/EC and a stable environment.

Download the nutrient burn (tip burn) SOP checklist A step-by-step checklist to diagnose tip burn in coco, pH → EC → environment.

Download now