Do I need Cal/Mag?

Hi smart people,

I have a crap shoot of plants started from seed, they are at variable stages due to the autoflower genetics present in the seedlot. The plants I want to concern myself with are coming into flower now/have been for a few weeks. Zero deficiencies, look healthy and robust. Seeded November 1, most are in full flower but some are just starting. Sown in peat, 3 gal pots, I’m using General Hydroponics as that was what was suggested to use at the time (what do you feel is better?). I attached two pics, one just starting and one further along.

Do I add Cal/Mag prior to visible deficiencies in lower amounts or do I wait for visible deficiencies to present? I feel I should add a lower amount now, but our water is high in bicarbonates so perhaps the plants are receiving enough cal/mag already? The water test shows 106.7 Calcium and 40.85 Magnesium (ug/mL). Can I push yield this way?

Thanks so much for your help.


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I am a few weeks behind you (11/15) and just entering flower, I did not use calmag until I could see visible deficiencies and even then I started at 1/4 strength. However unlike you my city water lacks in calcium so I do add calmag with all my waterings once I notice it’s needed, I grow in FFHF so it’s generally not needed till weeks 4-6…and I am also using general hydroponics and I like how simple it is to work with if using it in smaller doses. Your plants look great btw

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When I saw this, I knew it was time to start calmag, imo keep it simple, if they’re thriving let em continue

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me ive just started using calmag this grow. i start adding it once i start feeding at day 30± im in ffof soil so i dont need to add anything til then. but i add it every watering. i use 1ml/L. as recommended by my hydroponic store.

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Same here. Around week 5-6 I supplement a but of calmag myself. Starting out low and working my way up if I see deficiency. Also start of flower happens to be normally when u see deficiency start.

Your plants are a nice deep green. So be sure to pH ur calmag solution i to appropriate range for ur medium before pouring.

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COPY/PASTE the below list into your forum post.

Answer these simple questions the best you can.
If you do not know, or do not use something; Just say so; Or post
NA (non applicable)

-What strain, Seed bank, or bag seed (photo or auto)
-Age of plant
-Method: Soil w/salt, Organic soil, Hydroponics, Aquaponics, KNF
-Vessels: Type and capacity of container (fabric, plastic, etc)
-PH and TDS of Water, Solution, runoff (if Applicable)
-PPM/TDS or EC of nutrient solution if applicable
-Method used to measure PH and TDS
-Indoor or Outdoor if indoor, size of grow space
-Light system List brand and wattage/spectrum
-Actual wattage draw of lights
-Current Light Schedule
-Temps; Day, Night
-Humidity; Day, Night
-Ventilation system; Yes, No, Size
-AC, Humidifier, De-humidifier,
-Co2; Yes, No

If growing Hydro some additional questions:

-DWC? RDWC? Autopots? Ebb and Flow? Other?
-Distance of liquid below net pot (DWC)
-Temperature of reservoir
-TDS of nutrient solution
-Amount of air to solution

Always try to upload a clear picture in white light of any issues you may have to allow the community to assist you.

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Nothing wrong with the gh products. In racing we say run what ya brung. There is a cheaper more simple alternative but what you’re using is ok

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Is that what this is