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Soil is a complex buffer that slowly releases nutrients to plants over time. Remove the soil, and you become responsible for delivering everything your plants need, in the right form, at the right concentration. That’s the science behind hydroponic nutrition, and it’s more accessible than it sounds.
Key takeaways
- Plants need 17 essential nutrients, divided into macronutrients (needed in large quantities) and micronutrients (needed in trace amounts).
- pH level is the single most important factor in nutrient availability, most hydroponic plants thrive between pH 5.5 and 6.5.
- Electrical conductivity (EC) measures total dissolved nutrient concentration and is your primary indicator of solution strength.
- Organic and mineral nutrient solutions both work in hydroponics; the key is proper formulation and regular replenishment.
- Gardyn’s automated system delivers pre-formulated nutrition through yCubes, eliminating manual mixing entirely.
The 17 essential plant nutrients
Macronutrients
Macronutrients are required in relatively large quantities and form the backbone of any nutrient solution:
- Nitrogen (N): Drives leafy green growth and chlorophyll production. Nitrogen-deficient plants yellow from the bottom up.
- Phosphorus (P): Essential for root development, flowering, and fruiting. Critical in early growth stages.
- Potassium (K): Regulates water uptake, strengthens cell walls, and supports overall plant vigor.
- Calcium (Ca): Builds cell walls and is essential for preventing blossom end rot in fruiting plants.
- Magnesium (Mg): Central atom of chlorophyll molecules, magnesium deficiency shows as yellowing between veins.
- Sulfur (S): Supports enzyme function and protein synthesis.
Secondary and micronutrients
Micronutrients are needed in much smaller amounts but are equally essential. Iron, manganese, zinc, copper, boron, molybdenum, chlorine, and nickel all play specific roles in enzyme function, photosynthesis, and cellular processes. Most commercial hydroponic nutrient solutions include full micronutrient packages.
pH: the most critical variable
pH measures the acidity or alkalinity of your nutrient solution on a 0–14 scale, where 7 is neutral. In hydroponics, pH directly controls which nutrients are chemically available for root uptake, even a perfectly formulated solution becomes ineffective if pH is wrong.
| Plant type | Optimal pH range |
| Most herbs and greens | 5.5 – 6.0 |
| Lettuces | 6.0 – 7.0 |
| Tomatoes and peppers | 5.5 – 6.5 |
| Strawberries | 5.5 – 6.0 |
| Basil | 5.5 – 6.5 |
pH drift is normal in hydroponic systems, plant uptake, evaporation, and microbial activity all shift solution chemistry over time. Manual systems require regular pH testing and adjustment using pH-up or pH-down solutions.
EC: measuring nutrient concentration
Electrical conductivity (EC) measures the total dissolved solids in your nutrient solution : essentially, how “strong” the solution is. Higher EC means more nutrients dissolved; lower EC means a more dilute solution.
Most herbs and greens thrive between 1.2–2.4 mS/cm EC. Seedlings need lower concentrations (0.8–1.2) while fruiting plants can handle higher levels (2.0–3.5). EC that’s too high causes nutrient burn; too low leads to deficiencies and slow growth.
Managing both pH and EC manually requires a reliable testing kit and consistent attention. For a deeper guide, see our post on plant food and nutrient science.
Organic vs mineral nutrient solutions
Hydroponic nutrients come in two primary forms:
Mineral (synthetic) nutrients are highly soluble, pH-stable, and precisely formulated. They’re the industry standard for commercial hydroponics and most home systems. The plants can’t distinguish these from “natural” sources : a nitrate ion is a nitrate ion regardless of origin.
Organic nutrients derive from biological sources (fish emulsion, kelp, worm castings). They support beneficial microbial life in the root zone, but can be harder to dissolve fully and may increase the risk of algae growth in hydroponic reservoirs.
Both approaches can produce excellent results. For a nuanced look at mineral vs organic plant food, see our blog post: mineral or organic, settling the score on plant food.
What Gardyn does differently
For most home growers, the complexity of manual nutrient management is the biggest barrier to successful hydroponics. Gardyn’s approach removes that barrier entirely. Each yCube comes pre-seeded and pre-configured with the right starting nutrition. The system’s water reservoir, maintained at approximately 2 gallons per week, circulates continuously, Kelby, Gardyn’s AI assistant, monitors plant health and signals when attention is needed.
For growers who want to go deeper on nutrition science, Gardyn’s Gardyn plant food and HydroBoost supplements offer options to support fruiting plants and accelerate growth at different life cycle stages.
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Curious what’s growing in your Gardyn? See the full range of yCube plant varieties, from classic basil to cherry tomatoes, kale, mint, and jalapenos.
Frequently asked questions
How often should I change the nutrient solution in a hydroponic system?
Most systems benefit from a full reservoir change every 1–2 weeks, with top-offs of plain water in between as plants absorb and evaporate solution. Frequency depends on plant size, number of plants, and ambient temperature.
Can I use tap water in a hydroponic system?
Tap water works in most areas, but heavily chlorinated or very hard water can affect pH stability and nutrient availability. Letting tap water sit for 24 hours before use allows chlorine to dissipate. A water test helps identify any adjustments needed.
What happens if nutrient solution pH is wrong?
pH outside the optimal range causes nutrient lockout : the situation where nutrients are present in the solution but chemically unavailable to roots. Symptoms include yellowing leaves, stunted growth, and poor yields despite adequate nutrient concentration.
Do Gardyn plants need additional fertilizer?
yCubes are pre-configured for successful germination and early growth. Gardyn’s plant food supplement is available for growers who want to support fruiting plants or boost growth at specific stages. For most herbs and greens, the base system is self-sufficient.