Growing Degree Days (GDD) is a crop development metric used to estimate the growth stage of a plant based on accumulated heat units. Unlike simple calendar-based timing, GDD accounts for actual temperature exposure, making it more accurate for predicting plant development events such as germination, flowering, and harvest readiness.
Traditional schedules assume fixed dates for crop stages. But plant growth is driven by temperature, not time. GDD helps:
- Predict key development stages with greater accuracy
- Optimize nutrient scheduling and irrigation timing
- Enable early interventions based on real-time growth progress
- Improve harvest planning and crop uniformity
The basic formula:
GDD = (Tmax + Tmin)/2 – Tbase
Where:
- Tmax = Daily maximum temperature (°C)
- Tmin = Daily minimum temperature (°C)
- Tbase = Minimum temperature threshold for crop growth (typically 10°C for many crops)
If the result is negative, GDD for that day is considered 0.
GDD is cumulative, meaning it's added up day by day from planting onward.
Our sensor kits and climate logging platforms support real-time GDD accumulation by:
- Recording high-resolution temperature data (indoor/outdoor)
- Calculating daily and cumulative GDD automatically
- Displaying GDD progress alongside EC/pH logs and climate data
- Triggering alerts or suggestions based on growth phase alignment
We use GDD as part of our broader plant monitoring strategy to:
- Correlate microclimate with developmental pace
- Adjust light intensity or spectral mix based on growth phase
- Align fertigation settings to actual plant demand, not assumed calendar days
- Support AI-based growth models and digital twin simulations
We're currently exploring:
- Crop-specific GDD baselines for leafy greens and fruiting crops
- Integration of GDD into adaptive automation routines
- Combining GDD with humidity and solar radiation data to improve growth-stage prediction models
GDD is a foundational tool in our vision for data-driven, climate-responsive cultivation. It helps us move from static schedules to systems that adapt in real time to what the plants are actually experiencing.