Nutrient burn is the plant's response to more fertilizer salts in the root zone than it can take up. The treatment is simple in principle: stop feeding, run pH-corrected water through the pot until the runoff reads close to your target, then restart at a lower strength. Tips that already turned brown will stay that way. What you are watching for is clean new growth, which usually appears within three to seven days.
Why burnt tips show up first
Salts accumulate fast in a pot that gets fed on a schedule. Water evaporates, the remaining solution gets more concentrated, and the root tips sit in a stronger brew than the plant wants. Excess ions pull against water uptake, so the tissue farthest from the roots suffers first. Leaf tips and margins are the last place water arrives and the first place it runs short.
cannabis nutrient burn solution
Nitrogen is the usual culprit in veg and early flower. Too much of it produces dark, glossy, over-green foliage with leaves that hook down like a claw. Potassium and magnesium excess can cause similar tip necrosis, and a hard water source adds its own mineral load on top of your bottle feed.
Nutrient burn vs. other leaf problems
Misreading the symptom costs you weeks. A quick comparison:
Cannabis Nutrient Burn Solution
- Nutrient burn: burnt, crisp tips on many leaves at once, dark green color, clawing, runoff EC or PPM climbing above your input.
- Deficiency: yellowing between veins or from the bottom up, pale new growth, runoff EC lower than what you poured in.
- Light or heat stress: bleaching and crisp edges on the highest colas, leaves cupping upward, damage concentrated near the lamp.
- pH lockout: symptoms that look like several deficiencies at once, across leaves of different ages, with pH drifting out of range.
How to treat nutrient burn, step by step
- Measure runoff pH and EC or PPM before you change anything. That number tells you how bad the salt buildup is.
- Stop all nutrient additions, including boosters, calmag, and foliar sprays.
- Flush the media. In soil, pour roughly two to three times the pot volume of pH-adjusted water through it. Check pH in the 6.0 to 6.8 range for soil.
- Recheck runoff. If EC is still high, flush again and retest.
- Drain saucers and trays. Roots sitting in runoff reabsorb the salts you just removed.
- Wait three to seven days, then resume feeding at 50 to 75 percent of the previous strength, with nitrogen eased back.
- Trim only fully dead tissue. A leaf with a brown tip still photosynthesizes, so leave it until it dries out completely.
Soil
Soil buffers well, so a single thorough flush usually does the job. Let the pot dry back before the next watering. Some growers follow the flush with plain water for one or two weeks, which is safe but slows growth.
Coco and hydro
Do not flush coco or a reservoir with pure water. Coco holds cations loosely, and plain water strips calcium and magnesium out of the medium, which trades one problem for another. Flush coco with a mild nutrient solution at quarter strength, pH 5.5 to 6.2. In deep water or recirculating systems, dump the reservoir, mix a fresh batch at reduced EC, and run it through.
What not to do while plants recover
- Do not add a flush product, enzyme, or extra supplement to speed things up. You are trying to lower the salt load, not change its chemistry.
- Do not overwater during recovery. Soggy roots cannot take up what little nutrient is left.
- Do not jump back to full strength after a week of good growth. Step the EC up over several feeds.
- Do not chase the problem with more nitrogen in flower. Late nitrogen delays ripening and pushes leafy growth at the expense of bud development.
Recovery timeline and prevention
Expect stalled growth for a few days, then fresh tips that are green and flat. Full color and vigor return in one to two weeks for a mild case, longer if you caught it late in flower. Severe burn during bud development costs yield, and heavy stress late in the cycle can pull down the quality of the finished flower, which matters whether you grow for smoke or for CBD extraction.
The habit that prevents most of this: water to runoff every time, log the runoff EC next to your input EC, and raise feed strength in small steps instead of big jumps. If runoff EC climbs two feeds in a row, back off before the leaves tell you. Keeping pH in range and mixing nutrients at the label rate, not a rounded-up guess, covers the rest.