A greenhouse is a controlled environment, but that does not mean it is automatically optimal. The right combination of temperature and humidity makes a difference between 5 kg and 15 kg of tomato yield per plant.
Optimal values by culture
Each culture has its own preferences. Table of the most common:
| Culture | Day | Night | Humidity |
|---|---|---|---|
| Tomato | 22-26°C | 16-18°C | 60-70% |
| Paprika | 24-28°C | 18-20°C | 65-75% |
| Cucumber | 24-28°C | 18-20°C | 70-80% |
| Lettuce | 15-20°C | 10-15°C | 60-70% |
| Strawberry | 18-22°C | 12-15°C | 60-70% |
Temperature control
Passive mechanisms (without electricity):
- Thermal mass: 200 L of water absorbs daily heat, releases it at night (+3-5°C)
- Shading: 30-50% shade net in July (-5-8°C in the greenhouse)
- Mulching the soil: dark mulch absorbs more sun
Active mechanisms:
- Electric radiator (winter, only for vegetables)
- Kerosene heater (efficient, but gaseous atmosphere)
- Soil heating with a heat pump (most efficient, expensive)
Humidity control
Too high humidity (80%+) causes mold, gray mold, leaf spots. Too low (below 40%) causes stress and poor pollination.
Increasing humidity:
- Container with water in the sun (evaporates)
- Wet mulch around plants
- Morning misting of leaves
Decreasing humidity:
- More ventilation (main method)
- Watering only at the roots, never on the leaves
- Do not water in the evening
Ventilation and circulation
Proper ventilation is the most important climate control mechanism. In summer, the greenhouse must have 3-5 air exchanges per hour.
Ideal combination:
- Side openings (on both sides for cross ventilation)
- Roof openings (automatic with thermal cylinder)
- Circulation fan in the middle (prevents pockets of humid air)
Meters and automation
Investing in a good meter pays off quickly. We recommend:
- Basic: Min/max thermometer + hygrometer (15-25 €)
- Better: Wireless meter with archive (50-80 €)
- Pro: WiFi meter with phone alerts (Switchbot, Govee, 30-60 €)
- Automation: Thermal cylinder for automatic openings (40-60 €)
"Without a thermometer, a greenhouse is a game of chance. With it, it's a precise tool. Start with 20 €.", gardener and engineer, Murska Sobota
With good climate control, you can extend the season by 2 months in spring and 1 month in autumn, which is up to 25% more yield from the same land.
Automation for your greenhouse
Roof openings with thermal cylinders are standard on our Sigma and Profi greenhouses.
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