Growing medium and water
Set the growing medium for each plot – soil, coco or hydro – with the details that fit it: pots and watering, or reservoir, pump, pH, EC and water temperature.
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Growing medium per plot
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Open SensorsReference values
General guide values for herbs, vegetables and houseplants. Always check the needs of your own plant and the nutrient maker's instructions.
Search by plant
Type a plant name in English, Finnish or Swedish. Only published reference values are shown. If that plant has no number of its own, you get the general range and a note that says so.
pH
| What | Guide value |
|---|---|
| Garden soil, vegetable bed | 6.0–7.0 (Illinois Extension) |
| Peat and coco mixes | 5.5–6.5 (e-GRO) |
| Hydroponic nutrient solution | 5.5–6.5; lettuce 5.5–6.0 (UK CCD, OSU) |
EC – nutrient strength
EC (mS/cm) shows the amount of dissolved nutrient salts. Hydroponic nutrient solution by crop (OSU):
| What | Guide value |
|---|---|
| Lettuce | 1.2–1.8 |
| Basil | 1.0–1.6 |
| Sage | 1.0–1.6 |
| Parsley | 1.8–2.2 |
| Spinach | 1.8–2.3 |
| Peppers | 0.8–1.8 |
| Strawberry | 1.8–2.2 |
| Tomato | 2.0–4.0 |
Hydroponics: monitoring
- Check pH and EC daily at the same time of day; adjust pH only after EC is right (OSU).
- The optimum nutrient solution temperature is about 22–24 °C (72–75 °F) (OSU).
- In DWC, aerate and circulate the solution – the better the aeration, the better the growth (VCE).
- NFT needs constant circulation: a power cut dries the roots quickly. DWC's large water volume is more stable (VCE).
- A dissolved oxygen meter helps make sure the roots get enough oxygen (UK CCD).
Hydroponic systems
| System | How it works |
|---|---|
| DWC | Plants on floating boards in aerated nutrient solution. Inexpensive and stable (VCE). |
| NFT | A thin film of solution flows in channels; a pump circulates constantly. Popular for lettuce and herbs (VCE). |
| Ebb & flow | A tray is flooded on a timer and drains back to the reservoir. |
| Drip | Solution is dripped into a medium (e.g. coco, perlite); recirculating or not (VCE). |
| Kratky / wick | Passive: no pump. Suit small herb and lettuce containers. |
Watering and soil moisture
- Water when the top few centimetres are dry; a light pot is dry, a heavy one still moist (UMN).
- Pots need a drainage hole – never leave a pot standing in water (UMN).
- Hairy-leaved plants and soilless mixes can be watered from below via a saucer (UMN).
- Overwatering is the most common houseplant problem; the need depends on pot size, light and temperature (MU).
- A soil moisture sensor tells when to water – calibrate it in dry and wet medium.
Water source and quality
- Get a water test (pH, EC, alkalinity) before starting hydroponics and at least once a year (VCE, UK CCD).
- Subtract the source water's own EC from your reading when judging nutrient strength.
- Alkaline water (pH over 7) hurts nutrient uptake in hydroponics; pH is lowered with acid (UK CCD).
- Distilled, rain or RO water suits sensitive plants but needs a complete nutrient solution.
Sources
- Oklahoma State University Extension – Electrical Conductivity and pH Guide for Hydroponics
- University of Kentucky CCD – Hydroponic Lettuce Production in Controlled Environments
- Virginia Cooperative Extension – Hydroponic Production of Edible Crops: Management Basics, SPES-462
- e-GRO Nutritional Factsheet – Lettuce (substrate vs. hydroponic pH and EC)
- University of Illinois Extension – Starting a Garden: Soil Management
- University of Connecticut Home & Garden Education – Houseplant Watering Recommendations
- University of Missouri Extension – Caring for Houseplants (G6510)
- University of Maryland Extension – Target soil pH for vegetable crops, Table B-1
General home growing information – does not replace the instructions of your equipment or nutrient maker. Electricity and water: use a socket with a residual current device (RCD).