Growing cannabis is not as complicated as it may seem, but if you want to do it right and avoid any pitfalls along the way, here are five things you need to know about the pH of the water and how it affects your plants.
7 Things you Need to Know About pH of Water
First of all, what is pH, and why should we care? Have you ever noticed how some plants can do just fine with tap water while others show signs of deficiency as soon as the pH goes below 6.5? That’s because not all plants like acid water, and some (like cannabis) cannot grow in acidic soils.
1) Why do we need to measure and adjust pH?
Every plant (and every microbe, fungus, and insect) has a specific range of water pH it can tolerate, and getting the pH right is one of the most important things you will ever do for your plants. Even if you give them exactly the correct amount of light, water, and nutrients, they will grow poorly if the pH is wrong.
There are two reasons for this:
Some plants cannot tolerate acidic soils because their seeds cannot germinate in acidic conditions. While most seeds will grow at a slightly acid pH of 5, cannabis seeds have an optimum pH range of 6.5-7.0 to germinate and will only do so at a pH of 6 or below. And even if they grow in acidic conditions, the seedlings will likely die quickly.
The second reason is that plants cannot absorb some fertilizers when the pH is too low. pH has a tremendous effect on the solubility of nutrients, especially trace elements, which means that you may have all of the right ingredients, but if your pH is wrong, you won’t be able to use them.
Here’s what we need to know:
- It doesn’t matter how much NPK you provide if your pH is wrong.
- Cannabis likes slightly acidic water but hates alkalinity
Cannabis can grow well in neutral or slightly alkaline conditions (pH 6-8) but cannot tolerate high alkalinity, so the total dissolved solids must be low to mid-level. This includes things like calcium, magnesium, sodium, and potassium.
Location is also essential: Cannabis doesn’t like growing in water with a high total dissolved solids (TDS) level and will perform best in soft water with around 100-150 ppm. This TDS can only come from treating the source water to remove things like calcium and magnesium and replace them with sodium.
If you have a water softener or a reverse osmosis system, cannabis will grow best if you use the waste brine from the water softener as your base nutrients.
This step aims to reduce the TDS level to prevent “flooding” (which can happen when the water is too rich).
Water very high in total dissolved solids will cause a problem known as “flooding,” where the plant cannot get enough oxygen and nutrients to the roots. Flooded plants die quickly.
3. What is pH?
pH stands for “potential hydrogen” and indicates the presence of hydrogen ions in water. A pH of 7 means an equal number of hydrogen ions and hydroxide ions are present in the water.
4) Why does it matter?
The presence or absence of these hydrogen ions significantly affects your plants because they can affect nutrient absorption, cellular respiration, enzyme activity, etc. If the pH is too high or low, the nutrients will either tie up to other compounds and be unavailable for your plants or leach out of the soil.
5) How do I monitor pH levels?
There are some ways you can test pH levels, including:
-pH indicator strips – These work well enough but aren’t accurate.
-pH test kit – These are cheap and reasonably accurate, but you need to calibrate them regularly.
Electronic pH meters – A bit pricier than the test kits at first, but they’re reusable and more reliable in the long run. They also require less maintenance once you calibrate them.
6) I have my pH meter, so how do I keep it calibrated?
The calibration solution with the kit is suitable for maintaining tight tolerances over time, but you should still test the pH regularly. To calibrate your pH meter, use distilled water and let it sit out in the open for an hour or so.
7) How can I use this information to improve my marijuana harvest?
With all this knowledge, you should successfully grow a healthy crop of cannabis. Just keep your pH level in check and remember that, as with everything else, too much of a good thing is no good!
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