The short answer

Treat nutrient burn by stopping all fertilizer, watering with pH-balanced plain water, and checking the runoff EC and pH. Once the plant pushes normal new growth, restart feed at a lower strength. Do not try to fix it with more additives. Nutrient burn is a toxicity problem, so the cure is less, not more.

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What nutrient burn looks like

I look for burnt tips first. They turn brown or crisp while the rest of the leaf stays dark green. Leaves may curl down, claw, or feel stiff. In bad cases the burn moves along the leaf edge. These signs usually show on older leaves first because excess salts build up over time. Dark green leaves with burnt tips point to too much nitrogen or a general overfeed. Brown spots, yellow between veins, or pale new growth are more likely pH, deficiency, or root problems.

revive cannabis plants from nutrient toxicity

Light burn, heat stress, and wind burn can also crisp leaf edges. Check the distance to the lamp and the airflow before you blame the feed. If the burnt tips are uniform across the canopy and the EC is high, nutrient burn is a strong suspect.

what does nutrient burn look like on cannabis

Step 1: Stop feeding and check the root zone

Mix a plain water batch at the same pH you normally use. Water until you get enough runoff to test. Measure the EC and pH of the runoff. A runoff EC that is much higher than your input EC means salts are piling up in the medium. In soil, runoff EC is a rough guide, not a lab result. In coco and hydro, it is more useful.

revive cannabis plants from nutrient toxicity

  • Soil: water slowly to runoff, then let the pot dry back. Do not flush gallons through living soil unless the burn is severe and salt buildup is confirmed.
  • Coco: run a mild flush with low EC nutrient solution or plain water, then resume at half strength. Coco holds salts, so runoff testing matters.
  • Hydro: lower the reservoir EC by 0.2 to 0.4 and watch new growth. Dump and reset the reservoir if EC keeps climbing.

Step 2: Water correctly and wait

Overwatering after a burn makes things worse. Roots need oxygen. Water when the top layer is dry, not on a fixed schedule. Remove dead leaf tips only if they are crisp and easy to trim. Do not strip healthy leaves. The damaged tissue will not turn green again, so judge recovery by new leaves.

Recovery is slow. Expect 5 to 10 days before new growth looks normal in soil. Coco and hydro can show a change faster. If burnt tips keep appearing on new leaves after you lowered the feed, check pH, root health, and whether your EC meter is calibrated.

Step 3: Resume at a lower strength

Start at 50 to 70 percent of the last feed strength. Hold it for a week. Watch the newest leaves. If they come in flat and green with no burnt tips, raise the strength in small steps. If the tips burn again, drop back. A feed chart is a starting point, not a command. Cultivar, light intensity, temperature, and pot size change how much food the plant can use.

What not to do

  • Do not add more calmag, bloom booster, or root tonic to balance the burn.
  • Do not flush a living soil bed with huge volumes of water. You can wash out the biology you need.
  • Do not chase runoff numbers in soil the way you would in hydro.
  • Do not confuse burnt tips with normal fade late in flower.

Prevention that works

Mix nutrients at the strength your plant can use, not the strength on the bottle. Keep a log of input EC, runoff EC, and pH. Feed by plant response, not by convenience. Pre-mixed, one-part feeds and auto-dosing make overfeeding easy because the label dose is often too high for small pots and strong lights. Measure the runoff number, and adjust before the tips tell you.