How to PH Your Cannabis Plant

It is very important to know the PH (Potential of Hydrogen) of your Cannabis plants, because it controls the balance of nutrient uptake that you are feeding your plants. PH is the measurement of acidity and alkalinity, and while Cannabis plants prefer a more acidic growing medium for their roots, normal tap water from your faucet can sometimes be extremely alkaline. This conflict of PH between the watering mixture and the optimal PH of a cannabis’ growing medium, can create major deficiencies in your plant long term, hurting its overall performance including yield, cannabinoid percentage, and terpene expressions.


To control this delicate balance of PH, we must understand the PH required for each growing medium. Then we can measure the PH of the nutrient or plain water mixture we are giving to the plant and adjust according to the growing medium using a PH meter to find the PH then using PH Up & Down to adjust the mixture.

Growing Medium PH:

  • Soil = 6.4 PH

  • Hydroponic = 6.0 PH

  • Coco or Soil-less = 6.0 PH

The normal PH of tap water is around 8.0, so we can expect to use PH Down with most watering applications. Make sure to check and adjust the PH of your nutrient mixes after you have applied all the nutrients you are using, so you do not have to adjust the PH multiple times. It is important to remember that by using too much PH Up or Down, you will increase the salts in your mixture also measured in EC (Electro Conductivity) or PPMs (Parts Per Million) in your nutrient mixes. Keeping your plants growing medium at the optimal PH will give you higher yields, more fragrant plants, and overall more health throughout their vegetative and flowering lifecycles.


To best measure the PH of our cannabis plant, we need to have a PH meter, PH Up, and PH Down. You may also get a soil PH meter if you want to measure your soil medium directly. Hydroponic growers must measure their reservoirs on a daily basis to maintain PH balance, so getting a PH monitor instead of a basic meter, may be better. There are a variety of PH meters from disposable strips, to basic meters, all the way to high end, dual function meters. Also PH Up & Down products come in a variety of forms from chemical based to organic in nature, it is up to you to decide which is best for your PH control. I suggest using PH Up and Down products that do not add a lot of fertilizer to your mixture as you do not want to feed your plant on every watering and you must control the PH of even your flush, or plain water, cycles.

List of Basic PH Supplies

  • PH Meter (or basic PH testing strips)

  • PH Up

  • PH Down

Advanced PH Supplies

  • Dual PH/EC Meter (usually includes temperature as well)

  • PH Monitor (For Nutrient Reservoirs)

  • Organic PH Up & Down

  • Do-It-Yourself, Ex: Lemon Juice for PH Down

  • Soil PH Meter


  1. Only use a little amount of PH Up and Down at a time.

  2. Test your PH before adjusting it (even if you think you know based on a past result.) Give your reservoir or mixture time to settle after applying PH UP or Down, then retest the PH.

  3. Check your water runoff from soil containers to see if the PH of your initial mixture went down or up. This will let you know if your soil medium is too high or low in PH.

  4. If you see your plant get nutrient lock (leaves are turning brown in spots and not green or yellow,) you will want to flush your plants by giving them plain water around 6 PH at 1 to 3 times the volume of the container. Example would be 2 to 3 gallons of plain, PH adjusted water for every 1 gallon of your plant’s container size.

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