When to Adjust pH and PPM During a Cannabis Grow

When to Adjust pH and PPM During a Cannabis Grow : If you’re new to growing cannabis, it’s normal to assume that lighting is the most important aspect of a grow op. Or maybe you think it’s climate conditions like temperature and humidity. Then there are also factors like nutrients, ventilation, seed quality, and soil to consider.

Although each of these things is important for hearty, healthy plants, there are two more things that you should never overlook: pH and PPM. Too often do growers fail to even consider the pH scale or take PPM measurements, and even if they do monitor these things, many of them don’t know when it’s the right time to make adjustments.

That’s exactly what will be covered here in this guide to knowing when to adjust pH and PPM during a cannabis grow operation.

The Importance of pH and PPM Factors

In order to better understand when these adjustments to environmental factors like pH and PPM need to be made, you first need to have a basic understanding of why these factors are even important.

Why Focus on pH

For pH, which is the scale of how acidic or basic a solution is, it all has to do with how well the crop handles nutrients. Cannabis plants prefer their environment – we’re talking about the soil – to be slightly acidic, ranging between 6 and 7.

If your pH pen reads more than 7 and less than 6 when testing the soil, then the root systems will struggle to drink up nutrients that are delivered with each watering. In other words, the plants will struggle to eat. To simplify it, think of it like the temperature of the food you eat.

When food is too hot, you’ll burn your mouth, tongue, and it won’t feel good going down. Too cold and you’ll end up experiencing things like brain freeze and teeth sensitivity. Just right and the food with go down much easier. It’s exactly the same with pH.

Why Focus on PPM

PPM, which is short for parts per million, is a measurement of the total amount of dissolved solids (TDS for short) in the water you give your plants. To be honest, PPM isn’t nearly as important as pH, and it’s more of an advanced concept that new growers don’t necessarily have to worry about.

However, measuring PPM lets you know exactly how many minerals and substances are in the feeding water, and making adjustments can make a massive difference in the quality of the plants.

To give you a better idea of this measurement and how it works, most tap water falls within the range of 200 and 400 PPM. This means that there are between 200 and 400 milligrams of solubles for every liter of water.

A lot of growers prefer to start with purified water that has a PPM of 0 and then add in their nutrients and fertilizers while measuring the PPM as they do it. This lets them know EXACTLY what’s in the water without having to worry about feeding their plants the common contaminants found in tap water.

3 Reasons to Adjust pH and PPM

Before you can use a pH pen or PPM meter to make your adjustments, you must know when to do it. Here are the 3 biggest reasons to make changes to pH and PPM:

The pH Is Greater Than 7

As mentioned before, cannabis plants thrive in a slightly acidic environment. Ideally, each plant’s soil pH will remain somewhere between 6 and 7, but you only really have to worry about too much alkalinity when the soil runoff has a pH that’s 7 or higher.

In environments that are too alkaline (7+ pH), the root systems start to struggle with the process of uptaking and processing nutrients. Remember, you can think of it as food being too hot.
The pH Is Less Than 6

Just as pH that’s too high is an issue, the same goes for pH levels that are too low. In this case, you can think of it as your food being too cold to tolerate.

When the pH dips below 6 (of 5.5 for soiless hydroponic growing), the same thing happens as when pH creeps up too much. The soil becomes an intolerable environment for the roots to take up nutrients, which ultimately means the plants don’t get the nourishment they need.
The Crop Is Showing Signs of Nutrient Deficiencies

There are many things that could be causing nutrient deficiencies in a crop. It could be the result of pH that’s too high or too low, but it could also have to do with water PPM.

When there’s too much “stuff” in the water you feed to the crop and the PPM is extremely high, it could mean that you’re overdoing it on fertilizers and nutrients. It could also mean that the water you’re usint isn’t suitable for a grow op, which means it’s time to use purified water or invest in an RO system.

When the PPM is too low, it might mean that you’re not feeding enough nutrients to the plants. Either way, it’s always a good idea to check the PPM of the water as you mix in fertilizers and before you water the crop.

Keep in mind that these are just the 3 biggest reasons to make adjustments and you might come across other minor issues that could be resolved by making PPM and pH changes. You should be monitoring and maintaining pH and PPM throughout the entire grow op, not just when you run into problems. First focus on pH, then you can start paying attention to PPM.

How to Monitor and Adjust pH and PPM

The easiest way to make adjustments is by using the right tools. Invest in a pH pen and a PPM meter – there are even some tools that serve as an all-in-one pH-PPM reader, and some of them even measure more things like electrical conductivity (EC) and temperature.