Quick growing conditions
Air: around 18–30°C; nutrient solution: from 18°C
5.5–6.5
Approximately 2.0–2.5 mS/cm during fruiting
16 hours light / 8 hours dark; approximately 25–35 kilolux under white LEDs
Suitable systems
- drip
- DWC
Substrates
- perlite
How to Grow Hydroponic Cucumbers Indoors
Growing hydroponic cucumbers at home lets you pick fresh cucumbers just before eating them. You control their nutrition and plant care, and your harvest needs no transport or lengthy storage.
Grow your home cucumbers without chemical pesticide treatments. Start with disease-resistant hybrids, keep the system clean and inspect your plants regularly. Good growing conditions are the foundation of healthy plants and fresh, homegrown produce.
Hydroponic Cucumber Growing Conditions
| Parameter | Growing conditions |
|---|---|
| Air temperature | Around 18–30°C; growth is possible at 35–38°C in a greenhouse, but prolonged heat can reduce fruit production |
| Nutrient solution temperature | From 18°C in a cool room; growing near 30°C is possible with sufficient oxygen at the roots |
| Lighting schedule | 16 hours of light and 8 hours of darkness |
| Light at leaf level | Approximately 25–35 kilolux under white LEDs; aim for at least 25–30 kilolux |
| pH | 5.5–6.5 |
| EC during fruiting | Approximately 2.0–2.5 mS/cm |
| Space and support | Around 50–60 cm between plants, with a support approximately 1.8–2 m tall |
| First harvest | Approximately 45–60 days from germination for early hybrids under suitable conditions |
These are practical guidelines, rather than temperatures you must maintain exactly. Hydroponic cucumbers can fruit in a cool room around 19°C and continue growing in a hot greenhouse. Results depend on the hybrid, light, humidity, airflow and root health. During hot weather, reliable water delivery and ventilation become especially important.
There is no need to heat an 18°C nutrient solution to match the air temperature. As the solution approaches 30°C, pay particular attention to root oxygen supply.
Measure light at several points around the leaves. Kilolux readings are an approximate guide for white LEDs and should not be applied to red-and-blue grow lights.
Choosing Cucumber Varieties and a Hydroponic System
Choose parthenocarpic cucumber hybrids with stated disease resistance, particularly resistance to powdery mildew. Parthenocarpic cucumbers develop fruit without pollination, making them convenient for indoor growing. An all-female flowering habit alone does not guarantee this characteristic.
Mini and short-fruited cucumbers suit frequent picking for home use. Disease resistance reduces risk but still requires good plant care.
A drip system with a substrate such as perlite is suitable. Deep water culture (DWC) is another option with continuous aeration. Allow room for substantial root growth and provide a sturdy support.
Hydroponic Cucumber Nutrient Solution and Care
Recommended Nutrient Profile
All concentrations below are in mg/L of the finished nutrient solution.
| Element | Base, mg/L | Early growth, mg/L | Fruit set, mg/L | High water supply, mg/L | End of crop, mg/L |
|---|---|---|---|---|---|
| Total N | 242 | 235 | 256 | 242 | 228 |
| N–NO₃ | 224 | 224 | 238 | 224 | 224 |
| N–NH₄ | 18 | 11 | 18 | 18 | 4 |
| P | 39 | 39 | 39 | 39 | 8 |
| K | 313 | 274 | 352 | 274 | 313 |
| Ca | 160 | 180 | 160 | 180 | 160 |
| Mg | 33 | 39 | 33 | 33 | 33 |
| S | 44 | 44 | 44 | 44 | 44 |
| Fe | 0.840 | 1.400 | 0.840 | 0.840 | 0.840 |
| Mn | 0.550 | 0.550 | 0.550 | 0.550 | 0.550 |
| Zn | 0.327 | 0.327 | 0.327 | 0.327 | 0.327 |
| B | 0.270 | 0.378 | 0.270 | 0.270 | 0.270 |
| Cu | 0.048 | 0.048 | 0.048 | 0.048 | 0.048 |
| Mo | 0.048 | 0.048 | 0.048 | 0.048 | 0.048 |
Source: Nutrient Solutions for Greenhouse Crops, Geerten van der Lugt and co-authors, version 4, 2020, page 41. This table uses the cucumber feed solution for inert substrates, with adjustments calculated from the base profile.
Total N already includes N–NO₃ and N–NH₄. P and K are expressed as elements, not oxides. “High water supply” means irrigation above 5 L/m² per day. “End of crop” applies after removing the growing point while the last fruits ripen.
Use this hydroponic cucumber nutrient solution as a starting point. Adjust it during growth to suit your hybrid, source water, lighting and plant response. Use our NPK calculator to calculate fertiliser quantities for your chosen nutrient profile and water volume.
Check the reservoir level, cucumber pH and EC daily. After topping up, mix the solution and measure again. In recirculating systems, a complete solution replacement every 1–3 weeks is a practical starting schedule, depending on reservoir size and plant uptake.
For suitable hybrids that fruit on the main stem, train the plant to one stem and remove side shoots while small. When clips or ties support the stem, trim tendrils to prevent tangling. Keep healthy leaves, which support fruit growth, and follow the hybrid’s training guidance.
Harvesting Hydroponic Cucumbers
Pick cucumbers when they reach the hybrid’s expected size and remain green and firm. Cut the fruit stalk with clean scissors rather than pulling. Check daily: frequent harvesting prevents oversized fruit and reduces the load on the plant.
Common Hydroponic Cucumber Problems
- Small fruits turn yellow and stop growing: Check light, temperature, nutrition and the number of developing fruits.
- Plants wilt despite having nutrient solution: Check water delivery, solution temperature and roots. In DWC, confirm that aeration is working.
- Cucumbers become misshapen: Check the consistency of water supply, nutrition, lighting and fruit load.
- White powder appears on leaves: Powdery mildew is possible. Inspect the plant and improve airflow. Choose resistant hybrids and avoid overcrowding.
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Ranges depend on cultivar, stage, water, and environment.
Calculator overview →Sources
- Nutrient Solutions for Greenhouse Crops, Geerten van der Lugt and co-authors, version 4, 2020, page 41