Nutrient burn slows plant growth. It does not stop growth in most cases. Growth stops when salt damage reaches the root zone and the plant can no longer move water. A mild case costs 3 to 5 days of new growth. A severe case costs 10 to 14 days.

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What nutrient burn is

Nutrient burn is salt damage. The medium holds more fertilizer than the roots can take up. Water leaves the root instead of entering it. Leaf tips turn brown and crisp first. The burn then moves along the leaf edge. In cannabis, excess nitrogen also curls leaf margins down. Growers call that shape the claw.

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How nutrient burn changes growth rate

Burned tissue does not photosynthesize. With 10 to 20 percent leaf damage, the plant adds less mass per day. New nodes come in shorter. Stems can stretch more under high nitrogen, which makes the plant look taller while it adds less dry weight. Plants in veg lose growth speed in 2 to 4 days after salt levels rise. Plants in flower slow bud swell and can delay ripening by a week or more.

How to Prevent Nutrient Burn in Seedlings

When growth stops

A full stop points to root damage, not leaf damage. Signs: wilt in wet medium, brown root tips, no new white roots, a pH that drifts down, and runoff EC more than 1.0 mS/cm above the input EC. Roots that cannot take up water shut down expansion at the tips. Plants in this state sit still for 5 to 10 days.

does nutrient burn stop plant growth

Recovery steps

  1. Stop all feed. Water with pH 5.8 to 6.2 water.
  2. Push 2 to 3 times the pot volume through the medium.
  3. Measure runoff EC. Repeat the flush until runoff is within 0.3 mS/cm of the input.
  4. Wait 3 to 5 days. Resume feed at half strength.
  5. Watch new leaves, not old ones. New growth shows in 7 to 14 days.

Numbers to watch

What does not help

Plain water for a full week strips nutrients the plant needs and adds a second problem. Extra calmag does not fix salt burn. Cutting burned leaves does not restore growth. That tissue is already lost. Remove dead leaves that touch the medium, then leave the rest.

Prevention

Feed to runoff at least once a week in coco and rockwool. Check runoff EC at the same time. Raise feed strength in steps of 0.2 mS/cm, not jumps. Keep a log of input EC, runoff EC, and pH. A rise in runoff EC with a flat input EC means salt is building up, and a flush now costs less than a stall later.