Helllo, I’ve been having problems with my Sensi Big Bud and cannot figure out what’s wrong. The buds will simply not gain size!! It is now at 9 weeks of flowering and the lower buds show more growth than the top buds, top buds are not growing at all. The plant looks healthy apart from some issues with N toxicity. I also have a white widow in the same conditions and that one is doing fine. I am using a tried and tested grow room with no light leaks, temps never deviate from 20 - 30 C and I have a small circulation fan and exhaust. I have a pH/hygrometer. I have used the following on my last 2 grows:
250 W CFL (2700K)
Coco 7,5 L
GH flora series (with every watering until problems occurred, then reduced or skipped)
GH pH down (problem with coco and Phosforic acid?)
pH stayed within 5,8 - 6,2 range until problems started occurring
Soft water - 2dH. I let water stand so chlorine evaporates (I use GH micro for soft water)
And that takes us to today. After looking for many many hours on forums I still have not seen anyone with these exact symptoms. Leaves looked darker at some point due to N toxicity, the small leaves at the base of the top buds are a little deformed and some necrosis appeared in the middle of the plant, but only on a couple of leaves. The turgor pressure looks good, leaves dont droop at all, and almost no purple on petioles. The roots looked a healthy cream coloured but the root mass did look quite small, but it’s obviously taking up water so it must also take up nutes right? Because the thing to understand here is that the buds are not fattening at all, it’s not just stunted, it’s static. The only other factor is that both plants are seriously delayed because of the N toxicity.
These are the questions I have and “solutions” i have tried:
Ps. Water quality in my area:
Aluminium mg/l 0,03-0,1
Ammonium mg/l <0,02-0,04
Iron mg/l <0,05
Calcium mg/l 5,6-8,4
Koppar mg/l <0,01-0,03
Magnesium mg/l 1,2-1,5
Manganese mg/l <0,02-0,06
Conductivity 22-25,7
pH 8-8,2
250 W CFL (2700K)
Coco 7,5 L
GH flora series (with every watering until problems occurred, then reduced or skipped)
GH pH down (problem with coco and Phosforic acid?)
pH stayed within 5,8 - 6,2 range until problems started occurring
Soft water - 2dH. I let water stand so chlorine evaporates (I use GH micro for soft water)
- Vegetation went really well, however both plants stretched quite a lot in the 2 weeks after I switched to 12/12 and the Big B in particular looks very weak, with stems that are quite flimsy (N toxicity?).
- 3/4 weeks into flower and the BB was growing bud sites very quickly with 5-10 pistils per calyx. At that point i raised the pH to 6,2 (coming from 5,9 and aiming for 6,1) and gave full strength nutes. Bud growth slowed down and that seemed to affect the White W also.
- 3 days later gave it more nutrients and a bit of nute burn subsequently appeared on leaves.
- 3 days later and after seeing no change, watered with H2O only, pH in-out 6,1-6,1.
- 3 days later gave it water again in at 6,1 out at 6,4 which I assumed was the water adjusting up to reach equilibrium and that the nutrients were being taken up so gave it 1 liter half strength nutes at 6,1 as a top up immediately after checking the run off.
- After 2 days the WW looked better (and looks great today) but the BB did not, so a full flush was done with H2O only (forgot to let chlorine evaporate), in at 6,0 and out at 6,4. Improvement was minimal but I figured out the plant was suffering from N toxicity so expected plant to recover after flushing.
- 3 days later watered with half strength nutes in at 6,0 out at 6,2, and as I was worried that the coco was constantly wet, decided to wait 4 days before watering.
- 4 days later H2O only, in at 6,0 and out at 6,4.
- 2 days later and close to losing my mind, gave it nutes at pH 5,6 as that was the only thing i hadn’t tried yet (after all the pH kept rising in the medium so that seemed logical).
- After 4 days and no improvement I decided to flush again but with ⅙ of nutrient solution this time, with correct ratios, in at 5,8 out at 5,9. Still no improvement.
And that takes us to today. After looking for many many hours on forums I still have not seen anyone with these exact symptoms. Leaves looked darker at some point due to N toxicity, the small leaves at the base of the top buds are a little deformed and some necrosis appeared in the middle of the plant, but only on a couple of leaves. The turgor pressure looks good, leaves dont droop at all, and almost no purple on petioles. The roots looked a healthy cream coloured but the root mass did look quite small, but it’s obviously taking up water so it must also take up nutes right? Because the thing to understand here is that the buds are not fattening at all, it’s not just stunted, it’s static. The only other factor is that both plants are seriously delayed because of the N toxicity.
These are the questions I have and “solutions” i have tried:
- Now I’m waiting for the coco to dry up. I have done a foliar feed in case it’s a problem with the roots, no luck.
- Maybe the coco is compacted (7,5 L pots could suffer from lack of oxygen?) from so much watering, maybe I should try peroxide?
- Going back to the fact the BB has got weak stems, that is literally the only difference between the BB and the WW, could that be the problem?
- Another thing I have been thinking about is giving it some mycorrhiza, would that help?
- GH Flora apparently do not have an expiry date but i’m getting increasingly suspicious. However, the WW is doing alright. Maybe specific minerals like iron that react to create solids (residue at bottom of bottle)??
Ps. Water quality in my area:
Aluminium mg/l 0,03-0,1
Ammonium mg/l <0,02-0,04
Iron mg/l <0,05
Calcium mg/l 5,6-8,4
Koppar mg/l <0,01-0,03
Magnesium mg/l 1,2-1,5
Manganese mg/l <0,02-0,06
Conductivity 22-25,7
pH 8-8,2
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