How To Calculate Growing Degree Hours

Growing Degree Hours Formula:

\[ GDH = \sum \left[ \frac{(T_{max} + T_{min})}{2} - T_{base} \right] \text{ if } > 0 \]

Maximum Temperature (T_max):

°C

Minimum Temperature (T_min):

°C

Base Temperature (T_base):

°C

Growing Degree Hours (GDH):

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1. What Are Growing Degree Hours?

Growing Degree Hours (GDH) is a thermal time measurement used in plant growth models to quantify heat accumulation for plant development. It represents the cumulative heat units above a base temperature that plants require for various growth stages.

2. How Does The Calculator Work?

The calculator uses the Growing Degree Hours formula:

\[ GDH = \sum \left[ \frac{(T_{max} + T_{min})}{2} - T_{base} \right] \text{ if } > 0 \]

Where:

\( T_{max} \) — Maximum daily temperature (°C)
\( T_{min} \) — Minimum daily temperature (°C)
\( T_{base} \) — Base temperature for plant growth (°C)
\( GDH \) — Growing Degree Hours (degree-hours)

Explanation: The formula calculates the average daily temperature above the base temperature. Only positive values are accumulated, as temperatures below the base temperature don't contribute to plant growth.

3. Importance Of GDH Calculation

Details: GDH calculations are essential for predicting plant development stages, optimizing planting and harvesting times, pest management, and understanding crop responses to climate conditions.

4. Using The Calculator

Tips: Enter maximum and minimum temperatures in °C, along with the appropriate base temperature for your specific crop. Base temperatures vary by plant species (typically 0-15°C).

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between GDH and GDD?
A: GDH (Growing Degree Hours) calculates heat accumulation on an hourly basis, while GDD (Growing Degree Days) uses daily averages. GDH provides more precision for temperature-sensitive processes.

Q2: How do I determine the base temperature?
A: Base temperature varies by plant species. Common values: 0°C for cool-season crops, 10°C for warm-season crops, and specific values for different fruit trees and ornamental plants.

Q3: Can GDH be negative?
A: No, GDH values are set to zero when the calculation results in negative values, as temperatures below the base temperature don't contribute to plant growth.

Q4: What are typical GDH requirements for common crops?
A: GDH requirements vary widely: corn may need 800-2700 GDH, while fruit trees can require 200-1500 GDH for specific development stages like flowering.

Q5: How accurate is GDH for predicting plant development?
A: GDH is quite reliable for predicting phenological events but can be affected by other factors like photoperiod, water availability, and plant health status.