1. What is Vapor Pressure Deficit (VPD)?

Definition: VPD measures the difference between the amount of moisture in the air and how much moisture the air can hold when saturated.

Purpose: It's crucial for understanding plant transpiration rates, greenhouse climate control, and various agricultural applications.

2. How Does the VPD Calculator Work?

The calculator uses the formula:

Where:

• \( VPD \) — Vapor Pressure Deficit (kPa)
• \( T \) — Air temperature (°C)
• \( RH \) — Relative Humidity (%)
• \( \exp \) — Exponential function

Explanation: First calculates saturation vapor pressure, then adjusts for actual humidity to find the deficit.

3. Importance of VPD Calculation

Details: Proper VPD levels are essential for optimal plant growth, preventing water stress, and managing greenhouse environments efficiently.

4. Using the Calculator

Tips: Enter the temperature in °C and relative humidity (0-100%). The calculator will compute the VPD in kilopascals (kPa).

5. Frequently Asked Questions (FAQ)

Q1: What is the ideal VPD range for plants?
A: Most plants thrive at 0.8-1.2 kPa, but optimal ranges vary by species and growth stage.

Q2: How does VPD affect plant growth?
A: VPD influences transpiration rates - too high causes water stress, too low can lead to poor nutrient uptake.

Q3: What's the relationship between VPD and RH?
A: VPD considers both temperature and RH, providing a more complete picture than RH alone.

Q4: When is VPD most important to monitor?
A: Critical in controlled environments like greenhouses, indoor grows, and during sensitive growth stages.

Q5: How can I adjust VPD in my grow space?
A: Increase VPD by raising temperature or lowering RH; decrease VPD by cooling or humidifying.