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Nutrient Burn: Why Cannabis Leaf Tips Turn Brown and Crispy
By the Cultivar grow team · published 2026-08-04 · updated 2026-08-04 · how we source these numbers
Nutrient burn is the most self-inflicted problem in growing, and it comes from good intentions: a grower wants a bigger plant, so they feed more. What the plant actually experiences is a rising salt concentration in the root zone, and beyond a point it can no longer pull water in against it. The leaf tips — furthest from the stem, last in line for water — dry out and die first.
The counterintuitive part: burnt tips mean too much food, and the instinct to feed the "damaged" plant makes it worse.
Confirming it is actually nutrient burn
Nutrient burn has a distinctive signature:
- Starts at the very tip of the leaf and moves inward along the edges.
- Dry, brittle, brown — crumbles when you touch it. Not soft, not slimy, not spotted.
- Hits the biggest, best-fed leaves first — usually top and mid-canopy, in the strongest light.
- The rest of the leaf stays green, at least at first.
If that does not match, check these instead:
| What you see | More likely |
|---|---|
| Yellowing from the leaf base or between veins | Deficiency or lockout |
| Whole upper leaf surfaces pale or bleached white | Light burn |
| Brown spots in the middle of leaves, not the tips | Brown spots |
| Tips pointing down, whole leaf curled under, dark green | Leaf clawing / nitrogen toxicity |
A small amount of tip burn on a heavily-fed plant late in veg is common and not an emergency. Burn that advances week over week is.
What actually causes it
Four habits produce nearly all cases.
1. Feeding at label strength. Nutrient labels are written to sell nutrients, and are frequently stronger than a plant in a small pot under moderate light needs. Many growers run well under label rate without any loss of vigour.
2. Not enough runoff. If you water to exactly saturation with no excess, the salts you added stay. Do that for six weeks and the concentration climbs steadily even though your feed strength never changed.
3. Feeding into flower at veg strength. A plant's nitrogen demand drops once the stretch finishes. The feed that was correct in week 3 of veg is an overfeed in week 4 of flower.
4. Stacking supplements. Base nutrients plus cal-mag plus a bloom booster plus a silica product, each dosed at its own label rate, add to an EC nobody calculated.
Fixing it
Step one: measure, do not guess. Water with plain pH-corrected water and catch the runoff. Compare its EC to what you poured in.
- Runoff EC well above input EC — salts have accumulated. Flush.
- Runoff EC close to input — the root zone is not overloaded, and you should be looking at lockout or another cause instead.
Step two: flush properly, if the numbers call for it. Run plain pH-corrected water through the pot at roughly two to three times its volume, slowly, letting it drain. Re-check runoff EC as you go and stop when it approaches your input. A flush that leaves the medium swampy for days trades a salt problem for an oxygen problem — see drooping leaves.
Step three: let it dry. Do not feed into a soaked pot. Wait until the pot is genuinely light again.
Step four: resume lower. Come back at noticeably less than you were running, and increase only if the plant tells you it wants more. Pale new growth and slowing vertical growth are the signals to feed up. Deep, glossy, dark green leaves with slightly curling tips mean you are already at the ceiling.
Getting the habit right
- Water to runoff every time. Aim for meaningful excess, in the region of 10–20% of what you poured in, so salts leave rather than accumulate.
- Track EC in and EC out. Rising runoff EC over successive waterings is the early warning you can act on before any tips brown.
- Step feed down as flower progresses, rather than holding it flat.
- Add one product at a time. If you cannot say what each bottle is contributing, you cannot diagnose what went wrong.
Judging recovery
You are looking for two things, both on new growth:
- New leaves emerge without burnt tips.
- Existing burn stops advancing — the brown edge does not move further inward over the following week.
Leaves already burnt will stay burnt. Removing them does not help the plant and costs it the green tissue that is still photosynthesising, so leave them unless they are more than roughly half dead.
When burnt tips are not worth chasing
A plant finishing flower, being fed hard, with a few millimetres of tip burn on its largest fan leaves, is a plant near its ceiling rather than a plant in trouble. Correct the trend if it is advancing. Do not tear apart a working feed schedule over cosmetic damage on leaves the plant is about to senesce anyway.
- EC / TDS meter — the only way to know what your roots are actually sitting in rather than what the bottle said
- Digital pH pen + calibration solution — tip burn and lockout look similar and pH is what separates them
- Measuring syringe set — most overfeeding is eyeballed dosing, not a bad schedule
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FAQ
What does nutrient burn look like on cannabis?
It starts as yellow then brown crisping at the very tips of the leaves, usually on the biggest, healthiest, top-most leaves first. The damage is dry and brittle, works inward from the tip along the edges, and the leaf stays otherwise green.
Will burnt leaf tips heal?
No. Burnt tissue is dead and will not turn green again. You judge the fix by whether NEW growth comes in clean and whether the existing burn stops advancing — not by the damaged leaves.
How do I flush nutrient burn?
Water with plain pH-corrected water at roughly two to three times the pot's volume, until runoff EC drops close to your input EC. Then let the pot dry properly before feeding again, at a lower strength than before.
Why did nutrient burn appear when I did not change anything?
Salts accumulate. Feeding at a constant strength without enough runoff concentrates the root zone over weeks. Also, plants need less nitrogen as they move into flower, so an unchanged veg-strength feed becomes an overfeed the moment the stretch ends.
Is nutrient burn the same as light burn?
No, though they are often confused. Nutrient burn starts at leaf TIPS anywhere on the plant. Light burn affects whole leaf surfaces nearest the lamp, usually bleaching them pale or white rather than brown and crispy.
Keep reading
- Yellow Leaves on Cannabis: a 6-Question Decision Tree
- Nutrient Lockout: When Feeding More Makes It Worse
- Light Burn and Bleaching: Too Close, Too Bright, or Too Hot?
- Brown or Rust Spots on Cannabis Leaves: Calcium, pH or Pests?
- Bud Rot (Botrytis): Catching It Before It Takes the Harvest
- Drooping Cannabis Leaves: Overwatered or Underwatered?
- Fungus Gnats: Small Flies in Your Grow and the Larvae That Matter
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