Grow Guides / Root zone
Solution strength can influence how water and nutrients move toward roots. Learn what EC and PPM readings can tell you, where they fall short, and how to make a calmer next move.
Understand the readingsThe meter lens
Electrical conductivity (EC) measures how well dissolved ions let a solution conduct electricity. More dissolved mineral salts usually raise that conductivity, so EC is a practical shared language for solution strength. PPM or TDS displays are commonly estimated from EC using a meter-specific conversion factor; they do not identify which nutrients are present or whether a plant can use them well.
EC gives a direct conductivity reading that is easier to compare among meters and nutrient programs. It still needs context: source water, nutrient formula, pH, root-zone moisture, temperature, and plant demand all affect what a reading means in practice.
The same 1.0 EC solution can show roughly 500 ppm on a 500/0.5 meter and roughly 700 ppm on a 700/0.7 meter. The solution did not change—the display formula did. Check the meter setting or manual before comparing a PPM value with someone else’s chart, feed schedule, or log.
500 / 0.5 scale
PPM ≈ EC × 500
A meter using this factor will display about 500 ppm when the solution reads 1.0 EC.
700 / 0.7 scale
PPM ≈ EC × 700
A meter using this factor will display about 700 ppm when the same solution reads 1.0 EC.
Strength and uptake
Roots take up water through an osmotic gradient. When the solution around roots becomes too concentrated for the plant and conditions, water can become harder to take up. That can slow growth, reduce nutrient movement, and create deficiency-like symptoms even when nutrients are present. At the other end, a very weak solution may not match a plant’s needs—but light, root health, pH, temperature, and watering can produce similar visual signals.
01
Water uptake, oxygen, pH, and solution strength are working together. New growth is the most useful response signal.
02
Osmotic stress may contribute to leaf-tip burn, reduced water uptake, slow growth, and symptoms that can look like a deficiency.
03
Growth may be limited when the plant is otherwise healthy and actively demanding more nutrition, but verify the full root-zone picture first.
Grow system context
A usable EC or PPM range depends on cultivar, plant size, climate, source-water EC, substrate, nutrient formula, irrigation method, and feed schedule. Use the following as a way to choose the right context—not as a substitute for the label or a single number to chase.
Use as a supporting signal
Soil, organic amendments, microbial activity, moisture, and water alkalinity can make runoff or slurry readings incomplete snapshots. Follow the soil and product guidance before steering feed strength from one sample.
Watch input and runoff together
Frequent irrigation can make input, runoff, dryback, and salt accumulation trends especially useful. Compare like with like and keep the nutrient program, runoff method, and sampling timing consistent.
Track the reservoir trend
EC can move as plants take up water and nutrients, solution evaporates, or the reservoir is topped up. Pair the EC trend with water level, pH, temperature, root condition, and the manufacturer’s schedule.
Stage framework
01 / growth phase
Start conservatively and prioritize moisture, root establishment, light intensity, temperature, and gentle transitions. Young plants may need less nutrient strength than established plants, but cultivar and medium matter.
02 / growth phase
Increase only as plants are actively growing and the root zone is responding well. Compare the feed schedule with new growth, irrigation rhythm, environmental demand, and any input-versus-runoff trend.
03 / growth phase
Demand can change with plant size, climate, cultivar, and production goal. Avoid treating a stage label as a target: confirm the product schedule, source-water baseline, and root-zone response first.
Troubleshooting sequence
EC or PPM is most useful when measured the same way over time. Pair it with pH: a solution can have an appropriate EC while pH, poor root-zone oxygen, inconsistent watering, or a damaged root system still limits uptake.
Read the pH guideCheck: Confirm calibration, source-water EC, mixing order, sample temperature, and whether the plant is actually underfed rather than slowed by pH, overwatering, low root oxygen, pests, or environment.
Next: If the trend is confirmed, adjust according to the nutrient label in a small, measured step. Track new growth and the next comparable sample rather than making multiple changes at once.
Check: Look for a rising input-to-runoff gap, reservoir concentration, leaf-tip burn, reduced uptake, overly dry media, or a recent stacking of additives. High EC can create osmotic stress that resembles a deficiency.
Next: Review watering frequency and dryback, pH, product guidance, and system-specific leaching or reservoir-management practices. Make a gradual correction rather than a hard swing.
Check: Compare it with source water, input EC, pH, water level, and the time since the last irrigation or reservoir change. A rising trend can reflect more water leaving than salts, accumulation in media, or uneven sampling.
Next: Stabilize the routine, inspect root-zone moisture and drainage, then follow the substrate and nutrient manufacturer’s reset guidance. Re-test under the same conditions before escalating.
Measure cleanly
Do not chase the number
Change strength gradually, then give the plant and root zone time to respond. Avoid stacking a stronger feed, pH shift, additive, flush, and watering change into one correction. Observe new growth, keep your notes, and use the nutrient, substrate, and equipment labels as the primary operating guidance for your system.
Related guide / deficiency
Visual symptoms can overlap. Compare older and newer growth before assigning a concentration problem.
Open deficiency field guideRelated guide / toxicity
Concentration stress and toxicity can overlap with a suspected deficiency pattern, especially when roots are struggling.
Open toxicity field guideRelated guide / plant health
Pests and environmental stress can change how a plant looks and grows. Add a consistent inspection routine before you attribute every signal to feed strength.
Open IPM prevention guideWhen to scan
An educational Growlytics photo scan can help you document visible plant signals and compare them over time. A photo alone cannot determine EC, PPM, pH, or what is happening around the roots—pair it with your meter readings and growing notes.
This is general cultivation education, not a plant diagnosis or a substitute for local rules, product instructions, or professional horticultural guidance.