{"id":1225,"date":"2019-04-28T05:38:44","date_gmt":"2019-04-28T12:38:44","guid":{"rendered":"https:\/\/www.globalgarden.co\/?p=1225"},"modified":"2023-11-08T15:21:49","modified_gmt":"2023-11-08T23:21:49","slug":"vapor-pressure-deficit-vpd-explained","status":"publish","type":"post","link":"https:\/\/www.globalgarden.co\/knowledge\/vapor-pressure-deficit-vpd-explained\/","title":{"rendered":"Vapor Pressure Deficit"},"content":{"rendered":"

VPD Affects Plant Growth in a Big Way<\/h2>\nVapor Pressure Deficit sounds like a super complicated growing term at first for most growers. But we’ll make it easy to understand what VPD means and why it\u2019s so important to growing healthy plants. Hint: It\u2019s extremely important! Before we even get into what VPD means, we want you to know that we’re going to skip the formulas in this article. We want to keep the explanation as straight forward and practical, so you can take this information and apply it immediately. And you will. Trust me!\n

What is the Vapor Pressure Deficit or VPD of a Plant?<\/h3>\nVapor Pressure Deficit or VPD is very simply the measurement of how much drying power the air has. This effect’s the plant directly. The greater this force, the faster the plants dry out. The lower this force, the more moisture stays within the plant. If you remember from biology, in order to survive, plants need to transpire (like we sweat) through their stomata. In order to transpire effectively, the air needs to evaporate from their leaves within a certain range, not too fast and not too slow. Vapor Pressure Deficit is a numerical representation of this force. We can control VPD mainly by controlling temperature and humidity.\n

Why is VPD so Important!?<\/h3>\nKeeping VPD in the target range is crucial for healthy plant growth. It is probably the most straightforward way to understand the effect of temperature and humidity on your plants.\n\nWhen VPD is too high your plants will dry out rapidly. This can cause a range of issues. Some look like a nutrient deficiency, but mostly growth is retarded. Like really messed up. Stretchy plants. Crispy leaves. It looks bad, and it is bad.\n\nOn the other hand, when VPD is too low, moisture builds up on the surface of the plant’s leaves and growth is stalled. This happens because if the moisture can’t evaporate from the surface of the leaves, the plants can’t transpire. And that means they aren’t pulling up nutrients into their roots! Aaaand that means they aren’t growing. Period.\n\nWhat’s worse, low VPD usually creates the ideal environment to breed pathogens like Powdery Mildew or other fungi!!!! Enter sinister music and turn off the lights.\n

Finding the VPD of Your Plants<\/h3>\nOkay, so now it\u2019s time to learn how to actually figure out your VPD.\u00a0All you need is the VPD Chart below, the temperature of the room, the temperature of your plant\u2019s leaves, and you need the relative humidity of your grow room.\n\nWe recommend the following equipment:\n