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Growing Degree Day (GDD) Requirements for Each Growth Stage of Bell Pepper ​

Overview ​

In bell pepper (Capsicum annuum) cultivation, the accumulated temperature (Growing Degree Days: GDD) for each growth stage (germination, seedling, vegetative, flowering, fruit set/enlargement, and maturation/coloring) serves as an important indicator for predicting development and determining harvest timing. GDD represents the cumulative value of effective temperatures contributing to crop growth, and is used in many agricultural settings and research because it predicts development rates and growth stages more accurately than calendar days. Below, we present GDD values based on primary literature from both international and domestic sources, along with estimated values and their calculation bases for each growth stage.

Basic Information: GDD Definition, Base Temperature and Optimal Temperature for Bell Pepper ​

  • GDD Formula: GDD = (Daily mean temperature − Base temperature: Tbase). Daily GDD totals are accumulated over the growing period.
  • Base Temperature (Tbase): For bell pepper, 10°C is commonly used [1][2][3][4].
  • Optimal Temperature: 27–29°C during germination; approximately 21–27°C is recommended for most other growth stages [5][6][7][8].

GDD Requirements by Growth Stage ​

When direct GDD values for specific growth stages are unavailable, GDD is estimated using (1) reported duration (days) from literature, (2) typical measured mean temperatures, and (3) Tbase=10°C. The estimation method is specified for each stage.

1. Germination ​

  • Duration: 7–14 days
  • Typical Mean Temperature: 25°C (optimal germination temperature; 20–30°C range also reported in literature)
  • GDD Calculation: [(25°C - 10°C) × days]
    → Estimated GDD:
    • 7 days = 105 GDD (15×7)
    • 14 days = 210 GDD (15×14)

Reference: Optimal germination temperature and duration [5][6][7][8][9]

2. Seedling ​

  • Duration: 14–28 days
  • Typical Mean Temperature: 22.5°C (20–25°C)
  • GDD Calculation: [(22.5°C - 10°C) × days]
    → Estimated GDD:
    • 14 days = 175 GDD (12.5×14)
    • 28 days = 350 GDD (12.5×28)

Reference: Seedling stage temperature and duration [6][8][9][10]

3. Vegetative ​

  • Duration: Typically 6–8 weeks (42–56 days) from transplanting to flowering
  • Typical Mean Temperature: Around 22°C
  • GDD Calculation: [(22°C - 10°C) × days]
    → Estimated GDD:
    • 42 days = 504 GDD (12×42)
    • 56 days = 672 GDD (12×56)

Reference: Vegetative stage progression and temperature [8][9][10][11]

4. Flowering ​

  • Cumulative GDD to first flowering is often considered part of the vegetative stage, and the transition from flowering to fruit set/enlargement is also temperature-dependent.
  • Generally, flowering occurs 30–50 days after transplanting, with cumulative GDD of approximately 350–650 (accumulated from the vegetative stage).

Reference: Reports on flowering and GDD [10][11][12]

5. Fruit Set/Enlargement ​

  • From flowering to green mature fruit stage: 28–35 days (temperature range: 20–25°C)
  • GDD Calculation: [(22°C - 10°C) × days]
    → 28 days = 336 GDD
    → 35 days = 420 GDD
  • Field Data (Japan): In Kanagawa Prefecture (greenhouse bell pepper), cumulative GDD from flowering to mature coloring was 1,200–1,300°C (Tbase=10°C) [13].

6. Maturation/Coloring ​

  • From end of fruit enlargement to coloring: 14–21 days
  • Typical Mean Temperature: 22°C
  • GDD Calculation: [(22°C - 10°C) × days]
    → 14 days = 168 GDD
    → 21 days = 252 GDD
  • Field Data: The above 1,200–1,300°C represents the cumulative value from flowering to mature coloring in Japanese greenhouse-grown color bell peppers (Tbase=10°C).

GDD Summary by Stage (Table) ​

StageApprox. Duration (days)Mean Temp. (°C)GDD Base Temp.Estimated GDDReferences
Germination7–142510105–210[5][6][7][8][9]
Seedling14–2822.510175–350[6][8][9][10]
Vegetative42–562210504–672[8][9][10][11]
Flowering30–50 (after transplanting)2210350–650 (cumulative)[10][11][12]
Fruit Enlargement28–352210336–420[10][11][13]
Maturation/Coloring14–212210168–252[10][11][13]
Flowering to Coloring Total49–562210Approx. 1,200–1,300[13]

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Regional and Cultivation Method Variations and Considerations ​

  • These values assume a base temperature of 10°C and average open-field or greenhouse conditions.
  • Duration and GDD may vary depending on regional climate and cultivation method (open-field vs. greenhouse).
  • Domestic example (Kanagawa Prefecture, greenhouse): Flowering to mature coloring ≈ 1,200–1,300 GDD [13].
  • International estimates show similar ranges, with Tbase and temperature differences being the main sources of variation.

Details of GDD Estimation Method ​

  1. Duration (days) for each growth stage is based on reported literature values.
  2. Appropriate mean temperature (temperature range) for each stage is set based on physiological/ecological studies and cultivation guides.
  3. Base temperature (Tbase=10°C) is based on domestic and international cultivation guidelines and academic reports.
  4. GDD = (Mean temperature − 10°C) × Duration (days), estimated for each stage.
  5. If the daily mean temperature falls below 10°C, that day counts as 0 GDD.

Summary ​

The required accumulated temperature (GDD) for each growth stage of bell pepper, based on a base temperature of 10°C, is approximately estimated and reported as follows:

  • Germination: 105–210 GDD
  • Seedling: 175–350 GDD
  • Vegetative: 500–700 GDD
  • Flowering: 350–650 GDD (cumulative)
  • Fruit Set/Enlargement: 340–420 GDD
  • Maturation/Coloring: 170–250 GDD
  • Flowering to Coloring Total: Approx. 1,200–1,300 GDD (Kanagawa Prefecture greenhouse reference)

Accumulated temperature for each stage may vary due to weather conditions and cultivation environment; use of local observations or local guidelines is recommended.

Sources ​

[1] MRCC: Growing Degree Day Description : https://www.mrcc.purdue.edu/resources/growing-degree-day-description
[2] Vegetable degree-day models: An introduction for farmers and gardeners (OSU): https://extension.oregonstate.edu/catalog/em-9305-vegetable-degree-day-models-introduction-farmers-gardeners
[3] Growing degree-days: one equation, two interpretations: https://digitalcommons.unl.edu/usdaarsfacpub/83/
[4] About Growing Degree Days - GreenCast | Syngenta: https://www.greencastonline.com/growing-degree-days/learn-more
[5] Growing Sweet Peppers in Missouri: https://extension.missouri.edu/sites/default/files/legacy_media/wysiwyg/Extensiondata/Pub/pdf/agguides/hort/g06372.pdf
[6] Marshydro blog: What Are the Bell Peppers Growing Stages: https://marshydro.eu/blog/bell-peppers-growing-stages/
[7] Bell Pepper Plant Growth Stages (PepperGeek): https://peppergeek.com/bell-pepper-plant-growing-stages/
[8] 6 Bell Peppers Growing Stages (SpiderFarmer): https://spiderfarmer.ca/bell-peppers-growing-stages/
[9] Growing Peppers in a Home Garden (Univ. of Maryland): https://extension.umd.edu/resource/growing-peppers-home-garden
[10] Growth, Physiological, and Biochemical Responses of Ethiopian Capsicum annuum: https://pmc.ncbi.nlm.nih.gov/articles/PMC9840558/
[11] Growing Peppers | Extension | West Virginia University: https://extension.wvu.edu/lawn-gardening-pests/gardening/wv-garden-guide/growing-peppers-in-west-virginia
[12] Growing and Using Peppers | Prairies to Perennials: https://extension.illinois.edu/blogs/prairies-perennials/2020-08-13-growing-and-using-peppers
[13] カラーピーマン(パプリカ)の品種と生理生態的特性 (神奈川県): https://www.pref.kanagawa.jp/documents/27252/531907.pdf