Getting VPD (Vapor Pressure Deficit) right can increase your cannabis yields by 15-30% while reducing pest and mold issues. But memorizing different VPD targets for each growth stage? That's where a comprehensive VPD chart becomes your best friend.

This guide provides the exact VPD ranges used by commercial cultivators, with detailed charts you can reference throughout your grow. Whether you're running clones or growing from seed, these proven ranges will optimize your environmental controls for maximum plant health and yields.

Quick Reference: Cannabis VPD Chart by Growth Stage

Use our VPD Calculator to find your exact VPD based on your current temperature and humidity readings.

Stage-by-Stage VPD Breakdown

Seedling/Clone Stage: 0.4-0.8 kPa

Target VPD: 0.6 kPa

Why Lower VPD:

• Underdeveloped root systems can't handle aggressive transpiration
• High humidity reduces transplant shock
• Lower stress promotes faster root establishment

Typical Environment:

• Temperature: 72-76°F (22-24°C)
• Humidity: 65-75% RH
• Duration: 7-14 days

Environmental Tips:

• Use humidity domes for clones
• Gentle airflow to prevent stagnant air
• Lower light intensity (200-400 PPFD)
• Mist clones lightly if humidity drops

Signs You're in Range:

• Perky, upright leaves
• New growth appearing
• No wilting during lights-on period
• Healthy green color

Early Vegetative Stage: 0.6-1.0 kPa

Target VPD: 0.8 kPa

Why Moderate VPD:

• Root system developing, can handle more transpiration
• Encourages leaf development without stress
• Builds plant structure for future flower weight

Typical Environment:

• Temperature: 74-78°F (23-26°C)
• Humidity: 60-70% RH
• Duration: 14-21 days

Environmental Tips:

• Gradual humidity reduction from clone stage
• Increase light intensity (400-600 PPFD)
• Begin light training techniques
• Monitor for rapid vertical growth

Signs You're in Range:

• Multiple new nodes appearing weekly
• Thick, sturdy stems
• Large, dark green fan leaves
• No signs of nutrient stress

Late Vegetative Stage: 0.8-1.2 kPa

Target VPD: 1.0 kPa

Why Increased VPD:

• Established root system handles higher transpiration
• Promotes stronger stems and branches
• Prepares plant structure for flowering

Typical Environment:

• Temperature: 75-80°F (24-27°C)
• Humidity: 55-65% RH
• Duration: 3-6 weeks (strain dependent)

Environmental Tips:

• Continue training and pruning
• Higher light intensity (600-800 PPFD)
• Ensure adequate air circulation
• Monitor for pests as humidity drops

Signs You're in Range:

• Explosive vegetative growth
• Strong branch development
• Rapid recovery from training
• Healthy root development (in clear containers)

Early Flowering Stage: 1.0-1.4 kPa

Target VPD: 1.2 kPa

Why Higher VPD:

• Supports initial flower formation
• Reduces humidity-related mold risks
• Maintains nutrient flow during transition

Typical Environment:

• Temperature: 76-82°F (24-28°C)
• Humidity: 50-60% RH
• Duration: 1-3 weeks after flip

Environmental Tips:

• Begin 12/12 light cycle
• Reduce humidity gradually
• Increase air circulation
• Watch for pre-flowers and stretch

Signs You're in Range:

• Pistils appearing at nodes
• Healthy stretch (1.5-2x height)
• No signs of powdery mildew
• Continued vigorous growth

Mid Flowering Stage: 1.2-1.5 kPa

Target VPD: 1.35 kPa

Why Optimal VPD:

• Supports rapid flower development
• Maximizes resin production
• Prevents bud rot while maintaining growth

Typical Environment:

• Temperature: 77-82°F (25-28°C)
• Humidity: 45-55% RH
• Duration: 3-5 weeks

Environmental Tips:

• Maintain consistent environment
• Strong air circulation through canopy
• Monitor trichome development
• Support heavy branches if needed

Signs You're in Range:

• Dense flower formation
• Heavy resin production
• No signs of bud rot or mold
• Continued pistil development

Late Flowering Stage: 1.3-1.6 kPa

Target VPD: 1.45 kPa

Why Highest VPD:

• Prevents mold during final ripening
• Maintains nutrient flow to flowers
• Supports final trichome maturation

Typical Environment:

• Temperature: 75-80°F (24-27°C)
• Humidity: 40-50% RH
• Duration: 1-2 weeks before harvest

Environmental Tips:

• Maximum air circulation
• Monitor trichomes daily
• Consider brief drought stress
• Prepare for harvest timing

Signs You're in Range:

• Trichomes turning milky/amber
• Pistils changing color
• No mold or rot issues
• Final flower density increase

Temperature and Humidity Combinations for Target VPD

Quick Reference: Achieving 1.0 kPa VPD

Quick Reference: Achieving 1.3 kPa VPD

For precise calculations with your exact conditions, use our VPD Calculator - just input your temperature and humidity for instant VPD readings.

Strain-Specific VPD Considerations

Indica Dominant Strains

• Generally prefer slightly lower VPD (subtract 0.1-0.2 kPa)
• More sensitive to high transpiration rates
• Better mold resistance allows slightly higher humidity

Sativa Dominant Strains

• Can handle higher VPD (add 0.1-0.2 kPa)
• Evolved in tropical climates with higher transpiration
• May need lower humidity to prevent stretch

Autoflowering Varieties

• Follow vegetative ranges for first 3-4 weeks
• Transition directly to mid-flowering ranges
• Shorter timeline requires consistent conditions

Landrace Genetics

• Research origin climate for optimal ranges
• May deviate significantly from hybrid targets
• Often more adaptable to environmental fluctuations

Environmental Equipment for VPD Control

Monitoring Equipment

• Digital thermometer/hygrometer - Essential for accurate readings
• Data loggers - Track trends over time
• Infrared thermometers - Measure leaf temperature
• Environmental controllers - Automate adjustments

Humidity Control

• Humidifiers - Ultrasonic or evaporative for increasing humidity
• Dehumidifiers - Essential for flowering stages
• Exhaust fans with speed controllers - Fine-tune air exchange
• Intake fans - Bring in fresh, conditioned air

Temperature Control

• LED lights - Lower heat output than HPS
• Air conditioning - Precise temperature control
• Heaters - For cold environments
• Insulation - Maintains stable conditions

Troubleshooting Common VPD Problems

VPD Too High (Plants Stressed)

Symptoms:

• Leaf edges curling upward
• Rapid soil drying
• Stunted growth despite good nutrition
• Plants droop under lights

Quick Fixes:

• Increase humidity immediately
• Lower temperature if possible
• Reduce light intensity temporarily
• Ensure adequate watering

VPD Too Low (Weak Growth)

Symptoms:

• Soft, weak stems
• Pale leaf color
• Slow nutrient uptake
• Increased mold/mildew risk

Quick Fixes:

• Decrease humidity
• Increase temperature slightly
• Improve air circulation
• Reduce watering frequency

Fluctuating VPD (Inconsistent Growth)

Symptoms:

• Growth spurts followed by stagnation
• Random nutrient deficiencies
• Unpredictable plant behavior

Solutions:

• Install environmental controllers
• Upgrade to more precise equipment
• Create thermal mass (water containers)
• Improve insulation and sealing

Advanced VPD Techniques

Daily VPD Cycling

Professional growers often run higher VPD during lights-on and lower VPD during lights-off to mimic natural conditions:

• Lights On: Target VPD + 0.2 kPa
• Lights Off: Target VPD - 0.2 kPa

VPD and CO₂ Supplementation

With elevated CO₂ (1000-1500 ppm), plants can tolerate higher VPD:

• Standard Air: Use chart values
• CO₂ Enriched: Add 0.2-0.3 kPa to targets

Leaf Surface Temperature VPD

For ultimate precision, calculate VPD based on leaf temperature (typically 2-5°F cooler than air):

• Use infrared thermometer for leaf temp
• Calculate VPD using leaf temperature instead of air temperature
• More accurate representation of plant stress

Creating Your VPD Schedule

Week-by-Week VPD Targets

• Weeks 1-2 (Seedling/Clone): 0.6 kPa
• Weeks 3-4 (Early Veg): 0.8 kPa
• Weeks 5-8 (Late Veg): 1.0 kPa
• Weeks 9-10 (Transition): 1.2 kPa
• Weeks 11-14 (Mid Flower): 1.35 kPa
• Weeks 15-16 (Late Flower): 1.45 kPa

Daily Monitoring Routine

1. Check temperature and humidity every 4 hours
2. Calculate VPD using our calculator
3. Adjust environment if outside target range
4. Log readings to identify patterns
5. Make gradual changes (0.1 kPa adjustments max)

Downloading and Using This Chart

Print-Friendly Version

Save this article and print the charts for easy reference in your grow room. Laminate them to protect against humidity and moisture.

Mobile Reference

Bookmark our VPD Calculator on your phone for instant calculations when checking your grow room.

Integration with Grow Logs

Include VPD targets in your grow journal alongside feeding schedules and training notes.

Conclusion: Mastering VPD for Bigger Yields

These VPD charts represent years of commercial growing experience and scientific research. While every strain and setup is slightly different, following these ranges will dramatically improve your environmental control and plant health.

Key Takeaways:

• Start conservative and adjust based on plant response
• Consistency matters more than perfect numbers
• Use our calculator for precise, real-time VPD monitoring
• Combine VPD control with proper nutrition and lighting
• Document what works best for your specific setup

Remember: VPD is just one piece of the puzzle, but it's often the missing piece that separates good growers from great ones. Master these ranges, and you'll see stronger plants, faster growth, and significantly higher yields. For comprehensive environmental management beyond VPD, see our complete environmental controls guide.

Ready to optimize your grow room environment? Use our VPD Calculator to see exactly where your current conditions fall on these charts and get personalized recommendations for your growth stage.

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Complete your growing mastery with our guides on environmental controls, cannabis lighting optimization, DLI optimization, and advanced nutrition strategies for professional-quality results.