Sourced crop reference
Hydroponic pH & EC target reference
Compare published reference ranges without collapsing different sources or growing contexts into one unsupported optimum.
How units are shown
pH is dimensionless. EC is electrical conductivity and every value here is displayed in millisiemens per centimeter (mS/cm). One dS/m is numerically equivalent to one mS/cm.
Read the context first
A published range can vary with cultivar, growth stage, climate, system, source water, meter method, and nutrient formulation. These references are not universal guarantees or automatic dosing recommendations.
Reported reference ranges
The 8 records below cover five crops. Repeated crops intentionally preserve source or production context.
| Crop | Published context | pH | EC | Source |
|---|---|---|---|---|
| Lettuce | General hydroponic crop referenceThe source table does not identify cultivar, growth stage, climate, or hydroponic system for this row. | 6.0–7.0 | 1.2–1.8 mS/cm | Oklahoma State University ExtensionReported directly in Oklahoma State HLA-6722 Table 2; no ppm/TDS conversion or range averaging was performed. |
| Lettuce | Small residential or at-home hydroponic systemsUF/IFAS discusses multiple small-system types and does not tie this range to one cultivar or growth stage. Its later Further Considerations section gives a broader nutritive-solution EC range of 1.2–1.8 mS/cm without a paired pH. | 6.0–7.0 | 1.4–1.8 mS/cm | University of Florida IFAS ExtensionSelected from the Plant nutrition statement because it explicitly identifies lettuce, calls EC 1.4–1.8 mS/cm ideal, and supplies pH 6.0–7.0 together. The later 1.2–1.8 mS/cm statement is disclosed but not averaged or used to invent a second full record. |
| Basil | General hydroponic crop referenceThe source table does not identify cultivar, growth stage, climate, or hydroponic system for this row. | 5.5–6.0 | 1.0–1.6 mS/cm | Oklahoma State University ExtensionReported directly in Oklahoma State HLA-6722 Table 2; no ppm/TDS conversion was performed. |
| Strawberry | General hydroponic crop referenceThe table reports pH 6.0 as a single value and does not identify cultivar, stage, climate, or system. | 6.0 | 1.8–2.2 mS/cm | Oklahoma State University ExtensionThe single published pH value is preserved as 6.0–6.0 rather than expanded into an invented range. |
| Tomato | General hydroponic crop referenceThe source table does not identify cultivar, growth stage, climate, or hydroponic system for this row. | 6.0–6.5 | 2.0–4.0 mS/cm | Oklahoma State University ExtensionShown separately from the narrower mature-plant Virginia trial setting; the records are not averaged. |
| TomatoMature plants | Virginia trials using Dutch buckets, NFT, and media bagsThe values describe settings used after seedlings in reported Virginia trials; they are not a universal tomato prescription. | 6.5 | 2.0–2.5 mS/cm | Virginia Cooperative ExtensionThe publication explicitly cautions that it is not intended to provide exact parameters for a specific crop/system. |
| Pepper | General hydroponic crop referenceThe source row is labeled “Peppers” and does not identify cultivar, stage, climate, or system. | 5.5–6.0 | 0.8–1.8 mS/cm | Oklahoma State University ExtensionShown separately from the mature-plant Virginia trial setting because the published values differ materially. |
| PepperMature plants | Virginia trials using Dutch buckets, NFT, and media bagsThe values describe settings used after seedlings in reported Virginia trials; they are not a universal pepper prescription. | 6.5 | 2.0–2.5 mS/cm | Virginia Cooperative ExtensionThe publication explicitly cautions that it is not intended to provide exact parameters for a specific crop/system. |
Source records
university extension
Electrical Conductivity and pH Guide for Hydroponics
Oklahoma State University Extension · 2017
Authors: Bruce Dunn, Hardeep Singh
Locator: HLA-6722, Table 2: crop EC and pH ranges
Accessed: 2026-09-11
General hydroponic crop reference table; cultivar, growth stage, climate, and system are not specified per row.
The publication identifies EC as mS/cm. Values are retained as published and are not blended with narrower sources.
Open institutional source : Electrical Conductivity and pH Guide for Hydroponics ↗university extension
Growing Lettuce in Small Hydroponic Systems
University of Florida IFAS Extension
Authors: Germán V. Sandoya, Jonael Bosques, Francisco P. Rivera Meléndez, E. Vanessa Vassilaros
Locator: Specific Considerations — Plant nutrition (lettuce EC 1.4–1.8 mS/cm and pH 6.0–7.0); Further Considerations (nutritive-solution EC 1.2–1.8 mS/cm)
Accessed: 2026-09-12
The lettuce-specific Plant nutrition statement supplies EC 1.4–1.8 mS/cm together with pH 6.0–7.0 for small residential or at-home hydroponic settings. A later general nutritive-solution statement gives EC 1.2–1.8 mS/cm without a paired pH.
HydroRigor retains the explicitly lettuce-specific “ideal” 1.4–1.8 mS/cm statement because it supplies EC and pH together. The later 1.2–1.8 mS/cm statement remains disclosed; the two statements are not averaged or otherwise reconciled into an invented range.
Open institutional source : Growing Lettuce in Small Hydroponic Systems ↗university research
Hydroponic Production of Edible Crops: System and Crop Comparisons
Virginia Cooperative Extension · 2023
Authors: Toni Sperry, Amber Vallotton, Chris Mullins, Joyce Latimer, Holly Scoggins
Locator: SPES-466NP, pages 5–6, System Control Parameters — Nutrients
Accessed: 2026-09-12
Reported nutrient-solution settings for mature tomato and pepper plants in Virginia Tech/Virginia State hydroponic trials.
The publication says it is not intended to provide exact parameters for a specific crop/system; these values are therefore labeled trial settings, not universal targets.
Open institutional source : Hydroponic Production of Edible Crops: System and Crop Comparisons ↗