A ppm question

Ok so I found this info as far as feeding my plants as a Rough guide:


Seedling Stage:

PPM Range: 100-250 PPM (parts per million)
Seedlings are sensitive to strong nutrient solutions, so a mild concentration is appropriate. Start with a lower PPM and gradually increase as the plants develop.
Vegetative Stage:

PPM Range: 300-800 PPM
As the plants enter the vegetative stage and start growing more vigorously, you can increase the nutrient concentration. Again, start on the lower end and adjust based on the plant's response.
Flowering Stage:

PPM Range: 800-1200 PPM
During the flowering stage, cannabis plants generally have increased nutrient demands. Adjust the nutrient concentration accordingly, but be cautious not to exceed levels that could lead to nutrient burn.

My question is this, Is the the PPM of JUST the Ferts, or do these numbers go by the PPM of the water + the Nutes?

Example, the 250 ppm max for seedlings, if your water is 150 ppm does that mean you can only add 100ppm of nutes, or does that mean you can use 250ppm of nutes and Ignore the ppm of the base water?

You haven't indicated soil or coco?
Idk anything about soil but with coco I start seedlings 0.8/1.0ec
Vegging 1.2ec
Flowering 1.4/1.8ec.

Ec is a universal measurement it's fool proof, ppm has various scales which I'm not sure about.

You mix the nutrient to the total figure...0.5ec tap water + 1.5ec nutrient would make 2.0ec

Star Dog said:

You haven't indicated soil or coco?
Idk anything about soil but with coco I start seedlings 0.8/1.0ec
Vegging 1.2ec
Flowering 1.4/1.8ec.

Ec is a universal measurement it's fool proof, ppm has various scales which I'm not sure about.

You mix the nutrient to the total figure...0.5ec tap water + 1.5ec nutrient would make 2.0ec

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Dr Bugbees Peat/vermuclite blend 50/50
My water does have:
Iron 0.03 mg/L
Calcium 59 mg/L
Natural Fluoride 1.15 mg/L

I ask because there is no NPK in the water so wasnt sure if you counted the few base minerals in it or not. I am old school, PPM is what I know, PPM is what i have used in gardening food plants for 30 years so i use ppm lol

IndooorGardnerOhio said:

Dr Bugbees Peat/vermuclite blend 50/50
My water does have:
Iron 0.03 mg/L
Calcium 59 mg/L
Natural Fluoride 1.15 mg/L

I ask because there is no NPK in the water so wasnt sure if you counted the few base minerals in it or not. I am old school, PPM is what I know, PPM is what i have used in gardening food plants for 30 years so i use ppm lol

Click to expand...

Just to be pedantic, sometimes water can contain nitrates from things like agricultural runoff. My county water report lists a little bit of it present. PPM is important, because it gives you an idea of your starting water quality. The thing is, not everything that adds up in your water (contributing to total ppm) affects your EC. EC is the “electrical conductivity” of the water, due to ions. When you add ionic compounds (salts) to water, they disassociate and break apart into ions. These ions have charges (periodic table, remember any of this stuff from high school?) and it has to do with bonding affinities.

Long story short - and because I don’t feel like researching and re-learning all this to try and explain it properly - some of the stuff in your water doesn’t have any Impact on your EC because it’s inert. The EC is what your plant will care about more than the overall ppm. That ppm can be quite high, without contributing anything “useful” to the plant. EC is a more useful measurement for this purpose, of determining nutrient “strength” than ppm.

Edit : the grow shop manager at the place I used to frequent explained to me that nutrient companies write their ppm/ec recommendations with the expectation that people are starting with very low or 0 ppm water.

IndooorGardnerOhio said:

My question is this, Is the the PPM of JUST the Ferts, or do these numbers go by the PPM of the water + the Nutes?

Example, the 250 ppm max for seedlings, if your water is 150 ppm does that mean you can only add 100ppm of nutes, or does that mean you can use 250ppm of nutes and Ignore the ppm of the base water?

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Interesting you're using a Bugbee recipe…

It's the latter - PPM of the water + nutes. As indoor growers, it's up to us to provide everything that the plant has from the outdoors - light, air, rain, and chemicals. Light is "food", fertilizer is vitamins and minerals.