The top pick for nutrient burn is a plain water flush with pH-adjusted water run through the medium until runoff PPM lands in the 300 to 500 range on the 0.5 conversion, followed by 7 to 14 days of plain water and a half-strength refeed. It wins because it works in soil, peat, and coco, adds nothing that can burn the plant further, and gives you a number to track instead of a guess. The criteria behind that pick: how fast salts leave the medium, how much stress the plant absorbs, how long recovery takes, and whether the plant is in veg or in flower.

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Nutrient burn is a salt problem, not a nutrient problem. Excess fertilizer in the root zone pulls water away from roots and pushes leaf tips and margins into necrosis. Flushing removes the salt. It does not undo damage already done.

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How to confirm nutrient burn before you flush

Look at where the damage sits. Nutrient burn starts at the leaf tips, moves along the margins, and leaves the leaf blade itself flexible. Several other problems look similar from a distance.

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  • Nutrient burn: tips crisp and brown, margins curl down, damage on older and top leaves at the same time, feed strength was raised recently.
  • pH lockout: mixed symptoms across the plant, some deficiencies and some excess, runoff pH far from target.
  • Light burn: damage on the canopy closest to the lamp, upper leaves only, no tip pattern.
  • Root problems: wilting despite wet medium, slow water uptake, brown roots with a sour smell.
  • Overwatering: drooping leaves with firm stems, heavy pots, no crisp tips.

A cheap EC or PPM meter settles it. Measure the runoff. If runoff EC sits far above your input EC, salts have built up and a flush makes sense.

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Plain water flush for soil and peat

Soil and peat hold nutrients on exchange sites, so salts release slower than in coco. Use 2 to 3 times the container volume of pH 6.0 to 6.8 water. Pour slowly in stages, let the pot drain, and discard the runoff. Measure runoff PPM after each pass.

Pros

  • Works with whatever water and pH adjuster you already own.
  • Low stress when the medium drains well.
  • Repeatable: you can flush again in a few days if runoff PPM stays high.

Cons

  • Slow. Soil can take several passes to drop.
  • Risk of waterlogged roots if the mix holds water and you pour too fast.
  • It strips available nutrients, so a refeed is required later.

Best for: established plants in soil or peat with medium to heavy tip burn, especially in veg or early flower.

EC-monitored flush for coco and hydroponics

Coco and hydro respond fast. In coco, run pH 5.8 to 6.2 water through the pot and watch the runoff EC. In recirculating hydro, drain the reservoir, refill with plain pH-adjusted water, and run the system for 24 to 48 hours. In drain-to-waste hydro, top-feed plain water until runoff EC lands near your target input EC.

Pros

  • Fast. Coco and hydro can drop salt levels in a day or two.
  • Measurable. Runoff EC tells you when to stop.
  • Fits automated systems with a reservoir drain valve.

Cons

  • Plain water in coco can strip calcium and magnesium buffers, so watch for a magnesium deficiency after the flush.
  • Full-strength plain water in deep flower can stall bud development.
  • Requires a meter and a habit of logging numbers.

Best for: coco and hydro grows with rapid tip burn, high runoff EC, or a missed reservoir change.

Light corrective flush for early tip burn

If only the tips are brown and the plant otherwise looks healthy, a full flush is overkill. Drop feed strength by 25 to 50 percent, water to 10 to 20 percent runoff each feeding, and skip one scheduled feed. Some growers run one plain water pass between two feedings.

Pros

  • Almost no stress. Growth continues without a stall.
  • Fast to apply and easy to reverse if the plant asks for more food.
  • Keeps the nutrient schedule intact for flower.

Cons

  • Does not fix a heavy salt buildup.
  • Easy to underfeed if you misread the burn.

Best for: mild tip burn in early flower, or any plant that showed burn right after a strength increase.

What a flush will not fix

  • Root rot or pythium. Flushing a sick root system adds water it cannot use.
  • A broken pH meter. Recalibrate before you trust runoff numbers.
  • Light burn, wind burn, or heat stress at the canopy.
  • Damage already visible on existing leaves. Brown tips stay brown. Judge recovery by new growth.
  • Pre-harvest flushing. That is a separate practice with a different goal and a different timeline.

Recovery and refeeding

After a flush, expect new growth to come out clean in 5 to 10 days. Hold plain pH water until the plant shows a light, even fade, then refeed at 50 percent of the strength that caused the burn. Raise by small steps over the next 2 to 3 feeds. Keep runoff EC close to input EC and pH inside the range for your medium. Water less often during recovery, since flushed roots take up water slower.

Which flush fits your grow

  1. Soil or peat, moderate burn: plain water flush at 2 to 3 times pot volume, repeat in 3 to 5 days if runoff stays high.
  2. Coco, heavy burn: EC-monitored flush, then resume at quarter to half strength with added calmag.
  3. Hydro, rapid burn: reservoir change to plain water for 24 to 48 hours, then half strength.
  4. Mild tip burn, any medium: reduce strength and increase runoff, no full flush.
  5. Deep flower: use a light nutrient solution instead of plain water so the plant keeps building.

Convenience decides this more than any single product. The growers who recover fastest are the ones with a PPM meter, a drain plan, and a pH pen they trust. A flush is a measurement exercise, not a ritual.