Nutrient Deficiency Correction Strategy

Discussion in 'Growing Marijuana Indoors' started by jimsonweed, Nov 19, 2023.

  1. All,

    Growing some Runtz using FFOF soil and FF trio. Just entered 4th week of flower. Overall, the plant looks very healthy but some of the oldest leaves are starting to lighten a bit in color. There are some dark spots as pictured as well, though most of these are from a previous nutrient deficiency (I didn't start feeding until week 5 of veg). I'm more concerned about the light color than the spots. None of the newer leaves are affected at this point.

    I watch my pH like a hawk, so I'm leaning towards this being a mobile nutrient deficiency, perhaps early Nitrogen or Phos. pH of runoff is generally 6.2-6.5. During last feeding yesterday, PPM going in was 580 and PPM in runoff was 520. pH going in of 6.5, runoff pH of 6.2-6.3. Everything else is set up well, humidity generally <50%, temp in range, LED lights, etc.

    I've been using FF trio at 1/2 strength every other watering, watering about every 3 days now. Would you recommend increasing to 3/4 strength on next feeding? Should I do a 1/4 strength watering instead of plain water for the next one to give a little extra before the next feeding? I definitely don't want to overfeed, but I do watch the PPMs closely. Runoff PPMs have been in the 500s during feedings and then in the 200s or so when I give plain water. I'm leaning towards giving 1/4 strength next watering for a light boost and then doing 3/4 strength during next feeding, but then that will be 3 waterings in a row with nutrients. Alternatively, I could just do plain water next watering like I have been then up to 3/4 strength at next feeding, but that next feeding would be in another 5 or 6 days so I would have to wait a while. Please let me know your thoughts and I do appreciate the input!
     

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  2. be careful with the tiger bloom I would bump the input ppm to like 800 if it were me then feed water water feed etc...
     
  3. Thank you. That makes sense. So you would suggest doing this on the next one? I just did a feed yesterday (580 ppm). Then it would be two consecutive feeds (first at 580 ppm, next at 800ppm) followed by 2 consecutive waters and then resume normal feed water feed water schedule after?
     
  4. that would get you back on track IMO more nitrogen
     
  5. i use fish emulsion liquid from walmart it stinks but works wonders
     
  6. Sounds good. Alright, well she'll be due for a feeding tomorrow then. I've already made up the water, pH of 6.4 and ppm of about 750 using FF trio at 75% strength. Wish me luck, I'll keep you all posted! Thank you again
     
  7. This is one of my G13 autos when it was about 3-4 weeks into flower, yours looks to be overall in better shape, that being said I expect the fan leaves to begin to yellow and fade at stretch as the plant moves the nitrogen around, especially from older growth lower fan leaves that aren't getting much light are the first to start yellowing, then shriveling up and falling off eventually.
    20231109_124010.jpg

    As you can see, my newer growth is a decent although light shade of green, but the older fan leaves are almost turning yellow as they fade out, I used to try and prevent it, but anymore I'm just too lazy to just let nature take its course for the most part.

    The plants are now less than a month (estimated) from cutting, and the buds are rapidly building and maturing, while almost anything thats not a sugar leaf is crapping out. (4 inch trellis net holes, hard to see but most of the colas are already 4+ inches long)
    20231115_142336.jpg

    So anyway, assuming you want to take my advice (and there are a lot of people who know better than I do, as well as a lot of different ways to grow weed) because I'm also growing in basically all FF stuff (mostly ocean forest soil, big bloom ,grow big, tiger bloom)

    Here is what I was feeding in the first pic (and I'm feeding a bit more now as they end their cycle and really chunk up buds)

    I was watering every other day approx 1/2 to 3/4 gallon (7 gallon pots) there would be little to no runoff on a typical watering.

    Every other watering I'd mix nutes in with 3/4 to 1 full gallon depending on plant size I was doing (per gallon, per plant)

    5-7ml of grow big (until buds began to form, then I cut it out of the rotation)
    5-10ml of tiger bloom
    60ml of grow big
    2-4ml cal mag (mine is 1-1-0, so after stretch once big bloom out gone. That between the cal-mag and the tiger bloom N is more or less covered imo)

    Seems like you are feeding similar to how I was, possibly slightly less often, which may be something to check.

    I can't speak to any PH problems, though I can say growing in FF bag soil (happy frog or ocean forest) with just RO water I've never had a PH issue, which isn't to say that might not be in play as well, just that I don't have the knowledge to speak to that due to my situation (I have a whole house RO system so almost all grows use RO water) Obviously your water source may vary significantly.

    Anyway mate, you can find more details in any of my grow journals (pics are from my current one) if you desire, or apologies if none of this was helpful, in any case good looking plant and best of luck on the grow!
     
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  8. Yes, there appear to be many similarities! I just want it to make it to harvest haha. I'm still shell shocked from my last grow where I lost the crop! Though that was very clearly a very low pH problem which I don't have this time, but still worried about her!
     
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  9. Alright I fed her this morning. pH going in of 6.4 and ppm going in of 700-750. Runoff water was about 6.2-6.3 and ppm of 580, so I think she was definitely a bit hungry. Consequently the leaf yellowing seems to be slowing down, so hopefully this additional feeding wasn't too much. I will just plan to do plain water next watering and go back to water feed water feed cycles. Will continue 3/4 strength going forward unless the PPMs start getting too high or she shows signs of nute burn, though hopefully not since I'll be monitoring closely.
     
  10. I think overall you are on the right track mate, but like anything else, there is always room for improvement and fine adjustments (at least my grows) , but all other things being equal (and your and my grows are very similar from the info provided, although there are countless other factors that could be different), best of luck and fee free to look in on any of my grows if you are looking for some "pace car" plants to gauge against, and best of luck moving forward!
     
  11. After some thought, I'm thinking this is a potassium deficiency. I noticed it first when the buds started really packing on. This would make the most sense since the plant's demands right now are mostly K and Phos more so than nitrogen. It also has the appearance and behavior of K deficiency as well. I know my pH is in ideal range, so not a lockout issue. I've done two consecutive feeds now, one at 1/2 strength and the next at 3/4 strength as detailed above. Hopefully this does the trick and the deficiency stops spreading! Either way, I think I'm obligated to give plain water next to avoid any salt buildup. If the deficiency persists, I suppose I'll go up to full strength on next feed!
     

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  12. #12 jimsonweed, Nov 24, 2023
    Last edited: Nov 24, 2023
    Alright, did a plain watering today. pH going in of 6.5, ppm 54. Runoff pH 6.4, ppm 220. Will continue with 75% strength nutes next feeding and repeat feed/increase to full strength as needed. I think the deficiency has slowed down, but you can definitely see it in the lower leaves. However, the cola leaves all look nice, dark, and frosty. She's starting to stink! Feel much better being on the underfed side of things than overfed, much easier to correct.
     

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