PPM (Parts Per Million)

Now that we’ve talked a good deal about fertilizers and nutrients, let’s get into how we actually measure the amount of fertilizer salts that are actually in the water solution you’re using.  We measure this using a PPM (Parts Per Million) count.


PPM Meter

PPM Meter

You’ll need to acquire a decent quality PPM meter to be able to read these amounts, and there’s a wide spectrum of them out there ranging from cheap to super expensive, so make the choice that’s best for you and your budget, but will still get the job done.  We recommend checking out user reviews online and get a good feel for what will float your boat.   

Here’s a simple breakdown that can help you to gauge your ideal PPM counts depending on the growing stage:

  • Seedlings and clones – Keep to:    100-250ppm
  • (AFTER 10 Days) – Bump up to 500-600ppm – Maintain for next 2-3 weeks.
  • After 4 weeks, raise to 800-1000ppm
  • (Beginning of Budding):  take it up slowly to maximum of 1300ppm



  • You’ve got to be very careful for over-fertilizing so that you don’t burn up your leaves.  If you make this mistake, it is remediable, but you’ll need to quickly flush out your plant by drowning in pure water (recommended 4x the volume of the grow medium.)
  • Keep in mind that tap water has a pre-existing PPM count due to the mineral content of tap water.  You may want to simply measure your local tap water to know what you are dealing with so that you aren’t over fertilizing.  In using the guidelines above you’d want to subtract the amount of your water’s average PPM from the total recommended growing stage PPM count so that you are adding just the right amount without over doing it.
  • When you notice your buds hairs are about a quarter red in color, you can safely stop giving nutrients and switch over to just water.  The plant can use up the remaining nutrients it already has, and this move will help balance out the chemicals to give the end product a smoother, more well-balanced taste that isn’t too “chemicalish” in nature.

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