The Dude Grows Show

Autoflower PPM

Hey guys, currently growing 3 auto GDP’s and they’re looking beautiful. My town has great water with a PPM of 15 from the tap. A lot of grow guides talk about adding synthetic nutes in the 1-2 ml per gallon range. When I do this it only gets me to around 300-400 ppm per gallon. My question is is this enough? They are on day 43 from sprout. A lot of info I find says I should be feeding them in the 800-900 ppm range at this point. Should I be adding more nutes to get to that range or keep doing what I’m doing? If I need to add more to get higher PPMs should it be more bloom nutes and not as much micro? Any advice is appreciated. Thanks!


4 responses to “Autoflower PPM”

  1. Rasta_k_ Avatar

    great question Crunchy. when i started out i was playing around the PPM for autoflowers and finding best figure that works for me. I have a critical auto and diesel auto that are in 3 gal radicle bags and day 33. I always started out with feeding 1/4 of the nutrient strength. After a few deficiencies in the coco I fed Full strength base nutrients A/B (Advanced nutrients Sensi Grow A/B for coco, B-52 and recharge). I would only add micro nutrients and grow nutes until she shows flowering and then you can start feeding boosters and up to the P-K. My feed now for my autos is 700-750PPM with 0ppm RO water and PH is adjusted by the base nutes to 5.5-5.7. I found feeding lower PPM (in strain specific cases) that i was having more deficiencies . So from now on I feed my base nutrients at full strength (4mL per liter) and use my other nutes at 1/4 to 1/2 depending on how they look. I grow in coco so I can see how they react within a day or 2 normally. Start increasing your PPM by 100-150 until you reach a spot that is best. If you notice at 700PPM you are getting some burnt tips, back down to 550-600 and see if it persists.
    Thanks again for the question and hope it helps out. keep us updated on the outcome.
    Stay Irie!

  2. Coach Steve Avatar

    400-600 sounds right for the age of that plant. You can add more base nutes if the lower leaves start to yellow, but she could very well like 600ppm or less throughout. Go off of what your plant tells you, not the internet.

  3. BostonBAKEDbeans Avatar

    mephisto sour crack for me and i’m on well water at 150ppm. I’m in week 5 of a 10 week strain and these girls are drinking a ton. 2 days from dwc 5 gall feed changes and the ppms are down to 250-300 so they are eating and drinking. I can’ nip the calmag issuein the ass though. My point is it can be very strain specific. I always dialed things back on autos but these are loving the food. So like rasta said slowly bring it up and watch your tips for burn and find your sweet spot keeping in mind that in a week or two what burned them today may not burn them as they get bigger.

  4. Sir Coughsalot Avatar
    Sir Coughsalot

    If you are a salt grower, then it’s all about the TDS! The concentrations of the different nutrient lines vary widely between manufacturers and even between products from the same manufacturer. The best thing to do is get a gallon of your base water, 15ppm from the tap is AWESOME! Mix a tsp of your base in and see what the TDS is. In your case, it is about 300-400ppm… Now you can scale it! 2 tsp will get you 600-800ppm, 3 will get you 900-1200, and so on. Then just follow the previous advice on 1/4 nutes for seedlings, and up from there.

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