Nutrient burn happens when your cannabis plants take up more fertilizer salts than they can use. The fix is straightforward: stop feeding, flush the growing medium with plain water, and let the plant recover. Most plants show new healthy growth within one to two weeks if you catch it early.
What nutrient burn looks like
Before you flush, confirm the problem. Nutrient burn shows on the leaf tips first. They turn brown, crisp, or curl upward. Leaves may look dark green and shiny. Growth slows. Unlike a deficiency, which often starts on older or newer leaves depending on the nutrient, burn hits the tips of many leaves at once, especially near the top of the plant.
preventing cannabis nutrient burn with feeding schedule
Step 1: Stop feeding and flush
Stop all nutrient solutions right away. For soil, flush with three times the pot volume of pH-balanced water. For coco or hydroponics, run fresh water through the system for 24 to 48 hours. This removes excess salts from the root zone.
Step 2: Check pH and EC
After flushing, measure the pH and electrical conductivity (EC) of your runoff or reservoir. In soil, aim for pH 6.0 to 7.0. In hydro, 5.5 to 6.5. If EC is still high, flush again. Once EC drops, you can start a light feed.
nutrient burn during flowering what to do
Step 3: Resume feeding at a lower dose
Wait until you see new growth without burned tips. Then mix nutrients at half the strength you used before. Increase slowly over the next few waterings. Watch the leaf tips. If they stay green, you are on track.
What not to do
- Do not add more nutrients to fix the problem.
- Do not flush with ice water or extreme pH.
- Do not remove all affected leaves at once. The plant needs them for energy.
How long recovery takes
Damaged leaves will not heal. The goal is new growth. In soil, expect one to two weeks. In hydro, recovery can be faster, sometimes just a few days. If the burn was severe, it may take three weeks. Be patient.
Preventing nutrient burn next run
Start with a base nutrient line and follow the label. Measure EC or PPM every time. Water until you get 10 to 20 percent runoff in soil. In hydro, change the reservoir weekly and top off with plain water between changes. Keep a log so you know what worked.