How to Use a VPD Chart to Optimize Your Grow

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Vapor pressure deficit (VPD) is an important metric for monitoring your cultivation’s ecosystem. With the help of a VPD chart, you can calculate where the relative humidity of your grow room intersects with the temperature, which in turn will tell you whether you need to adjust your room controls to facilitate better plant growth.

A typical VPD chart is color-coded to show you the recommended VPD ranges for each stage of plant growth. If your current VPD falls outside of that range — be it too humid, too warm, etc. — you’ll need to tweak your controls accordingly.

Higher Yields Consulting How to Use a VPD Chart to Optimize Your Grow


While measuring VPD is fairly straightforward, finding the VPD sweet spot for your grow can take a lot of trial and error over multiple harvests. However, getting expert guidance and using the latest technology can help you eliminate much of the guesswork and find your ideal VPD faster.

Read on to learn more about how to use a VPD chart and other tools to monitor your cultivation’s ecosystem and optimize your grow for higher yields.

How VPD Affects Your Grow

In essence, VPD is all about air, humidity, and the plants’ transpiration rate. If the VPD is too high, that means your ambient air is too dry and is causing your plants to transpire too rapidly. This can result in overdrying and plant stress. If it’s too low, the air is too humid, and the plants may not be transpiring quickly enough.

To prevent either extreme, it’s important to check your VPD numbers throughout the day. To ensure you’re staying within the sweet spot for your plants’ current stage of growth, there are three areas of importance to measure and compare with your VPD chart:

  • Room temperature: Measured by a thermometer.
  • Leaf temperature: Measured by an infrared thermometer.
  • Humidity: Measured by a hydrometer.

By managing the VPD, you can manage the rate at which your plants transpire and in turn control the metabolic rate of the plants to prevent problems in their growth.

How to Optimize Your Cultivation With a VPD Chart

The key to managing VPD effectively is to record your data and know what your cultivars need. However, it can take a lot of trial and error to find the sweet spot for your particular cultivars and facility.

Higher Yields Consulting How to Use a VPD Chart to Optimize Your Grow

At the end of each crop cycle, you’ll want to review your VPD chart numbers and compare them to the last. If your current cycle gave you a comparatively high potency and/or yield, what VPD numbers did you maintain this time versus during a previous, lower-yielding cycle? That will give you a better idea of your ideal VPD.

However, you don’t have to spend all that time on trial and error. If you work with experts who have experience analyzing VPD chart data on many different cultivars, you can eliminate the guesswork and get ahead of the game.

How to Leverage Emerging Technology for Higher Yields

When gathering your VPD data, you have a couple of options. As mentioned above, you can manually measure the room and leaf temperatures and humidity and plug those numbers into a VPD chart. Or, you can use high-tech options like the ones included in the HYC data suite to:

  • Collect data such as temperature and humidity
  • Analyze the data and track changes over time
  • Create and implement data-informed tasks for your team
  • Optimize your facility for maximum yield

From choosing the right lighting for each stage of plant growth to monitoring VPD chart numbers and maximizing airflow, there’s a lot that goes into getting the most out of your cultivation. With the right tools and expert help, you can ensure nothing prevents your grow from reaching its full potential.

Finding the Sweet Spot

Even with the help of a VPD chart, it can be challenging and time consuming to learn the precise VPD sweet spot your cultivars need. By working with the right experts and technology, though, you can skip past a lot of the trial and error and set up your grow for success.

Contact us today to learn more about how the Higher Yields Consulting data suite can help you optimize your grow for better and higher yields.

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