The short answer
Nutrient burn is salt stress caused by a feed strength that outran what the plant can take up. Stop feeding at the current rate, run water adjusted to the correct pH through the medium until the runoff clears, and wait. Resume nutrients at half your previous strength once new growth comes in flat and green, then step the strength up in small increments while watching the leaf tips. If leaves keep crisping after two or three days of plain water, the real driver is usually root zone pH drift or accumulated salts, not the fertilizer itself.
How to tell nutrient burn from look-alike problems
Nutrient burn shows up on the newest and mid-level leaves first: tips brown and curl upward, margins turn crisp, and the surrounding leaf stays dark green and waxy. A deficiency usually starts on older, lower leaves and often shows yellowing between the veins. Light or heat stress tends to hit only the top canopy and bleaches rather than browns. A pH lockout mimics a deficiency across the whole plant because nutrients are present but unavailable. Overwatering gives you droop and soft, dark foliage with no crisp edges. Getting the diagnosis right matters more than any bottle you buy.
Cannabis Nutrient Burn Treatment Guide
What to look for when you buy a fix
- A pH pen with 0.1 resolution, two-point calibration at 4.0 and 7.0, and a replaceable probe. Store the probe in potassium chloride storage solution, not distilled water.
- An EC meter rather than a TDS meter. TDS readings depend on the 0.5 or 0.7 conversion factor and cause confusion when comparing notes with other growers.
- Separate pH up and pH down solutions. Adjust in small amounts and re-check after mixing.
- Plain, pH-corrected water does most of the work. A chelated flushing agent is optional and should never replace correct pH.
- A runoff tray and a clean catch container so you can compare what goes in with what comes out.
- Calibration buffer packets with a printed expiration date. An uncalibrated meter is worse than no meter.
Parameter bands worth targeting
- Feed strength: roughly 1.2 to 2.0 EC during vegetative growth and 1.8 to 2.6 EC in flower for most cannabis cultivars in soilless systems. Start lower than you think you need.
- Runoff EC: within 0.3 to 0.5 EC of your input. A wider gap means salts are building up in the medium.
- Root zone pH: 5.8 to 6.2 in coco and hydroponics, 6.0 to 6.8 in soil mixes.
- Water temperature: 18 to 22 C, or 65 to 72 F. Warm reservoirs hold less dissolved oxygen.
- Recovery feed: 50 percent of the EC that caused the burn for the first week back.
Recovery steps
- Stop all nutrient additions and note the current EC and pH.
- Mix plain water, adjust it to the correct pH for your medium, and pour it through slowly until runoff runs clear and its EC drops close to your source water.
- Let the medium drain fully. Do not leave the pot sitting in runoff.
- Wait three to five days. Burned tissue will not heal, so judge progress by new growth only.
- Return with a half-strength feed and check runoff EC two days later.
- Raise strength in increments of about 0.2 EC per week until tips stay clean.
Pitfalls to avoid
- Flushing with untreated tap water at the wrong pH, which can lock out calcium and magnesium.
- Over-flushing soil, which strips nutrients and leaves roots waterlogged.
- Panicking over one browned tip. A single tip is a signal to watch, not a crisis.
- Jumping straight back to full strength once the plant looks better.
- Adding a bloom booster or additive during recovery. Change one variable at a time.
- Trusting a meter that has not been calibrated this month.
FAQ
How long does recovery take?
Damaged leaves stay damaged. Expect visible new growth within five to ten days and a full return to normal feeding over two to three weeks.
Do I need a flushing product?
Usually not. Plain pH-corrected water removes accumulated salts. Flushing agents can help in coco or dense media, but they do not replace correct pH and runoff monitoring.
Can I just top off the reservoir with water?
Topping off dilutes the solution but does not remove salts already bound in the medium. In recirculating systems, drain and replace the reservoir instead.
Is nutrient burn the same as nutrient toxicity?
Toxicity is the broader condition of excess nutrient availability. Burn is the visible leaf symptom that usually comes with it.
Should I use distilled water to flush?
No. Distilled or reverse osmosis water has almost no buffering capacity, so pH swings hard. If you use it, add back calcium and magnesium first.