Hydroponic plants depend on the nutrient solution for everything roots normally get from soil. That means regular plant fertilizer is not enough unless it is specifically designed for hydroponics and contains the right nutrients in soluble form.
Beginners should use a complete hydroponic nutrient, measure pH, and learn EC or TDS after the first few grows. Guessing nutrients works until it fails, usually with yellow leaves, tip burn, bitter lettuce, or stalled growth.
For meters, read Best pH Meter for Hydroponics.
Last updated: June 6, 2026.
Quick Answer
Use a complete hydroponic nutrient formulated for your crop, mix it according to label, check pH after mixing, and monitor EC for crops like lettuce and herbs. Do not use regular garden fertilizer or soil fertilizer spikes in hydroponic reservoirs.
What Nutrients Plants Need
Hydroponic nutrients include:
- nitrogen
- phosphorus
- potassium
- calcium
- magnesium
- sulfur
- iron
- manganese
- boron
- zinc
- copper
- molybdenum
A complete nutrient includes macro and micronutrients.
pH and EC Basics
| Measurement | What it tells you |
|---|---|
| pH | nutrient availability and acidity |
| EC | total dissolved fertilizer salts |
| TDS/ppm | estimated dissolved solids |
| water temperature | oxygen and root health |
For lettuce, OSU extension lists pH and EC ranges by crop and notes lettuce around EC 1.2 to 1.8 and pH 6.0 to 7.0 in its table.
Mixing Tips
- Start with clean water.
- Add nutrients according to label.
- Stir well.
- Let solution settle briefly.
- Measure EC if using a meter.
- Adjust pH after nutrients are mixed.
- Add to reservoir.
Do not mix concentrated A and B nutrients together before diluting; they can precipitate.
Common Beginner Mistakes
- using soil fertilizer
- never checking pH
- making nutrients too strong
- topping off only with nutrient solution
- letting water get too warm
- using clear reservoirs that grow algae
- ignoring root color and smell
For lettuce flavor issues, see Why Hydroponic Lettuce Turns Bitter.
FAQ
Can I use Miracle-Gro in hydroponics?
Use only products labeled and formulated for hydroponics. General soil fertilizers may lack required soluble calcium, magnesium, or micronutrient balance.
How often should I change hydroponic nutrients?
Small home reservoirs are often changed every 1 to 3 weeks depending on crop, reservoir size, water quality, and EC/pH drift.
What pH is best for hydroponics?
Many crops grow well around pH 5.5 to 6.5, but crop-specific ranges vary. Follow crop and nutrient guidance.
Related Reading
- Best pH Meter for Hydroponics
- Best Hydroponic System for Lettuce
- Kratky Method vs Deep Water Culture
- Why Hydroponic Lettuce Turns Bitter