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Fixing a Phosphorus Defiency


New Member
This is my first time tryin to grow in the winter, I'm just growing one Platinum OG that I got as a teen. I've been vegging for a couple months now, pretty much ready for flower but I want her in the best shape before I flip so I'm trying to fix this phosphorus problem I've been battling for weeks now. It's been colder than usual in Cali and my house insulation sucks, at night it gets in the 50s in my house when I don't run the heater. I thought the cold was locking out phosphorus in my plant, it's clearly showing all the signs of a phosphorus defiency and has been for weeks now, started with the lowest leaves on the plant and it's slowly affecting more leaves higher up.

I exhaust into a room now to raise temperature, turn exhaust off at night cuz I'm in veg, and have a heating mat under the pot that runs during lights off to keep the temps up to 60. The problem is that I fixed the cold issue a while ago and the plant doesn't seem to be improving, online advice says to feed nutes to fix defiency, I've fed full strength n it still doesn't seem to help. I'm now worried that I could have too much of another nutrient that is locking out the phosphorus. The plant hasn't shown any signs of being over fed at all but I feel like I'm giving plenty of nutes. I don't really know what else could be the problem. At this point I kinda feel like flushing is my last option.
Is there anything else I can do?

I'm in the process of brewing some compost tea and I'm trying to make it more of a fungal dominated tea since fungi aids the plant in absorption of phosphorus but I don't know if that'll help.


Well-Known Member
Your intuition is correct. Flush her good. It won't hurt your lady, and will wash out the extra salts.

After the flush, feed her only plain water for two weeks and watch the new leaves, as well as the old. When you see improvement, start giving her bloom nutes at 1/4 strength for about a week or two before switching her to 12/12. This will give her time to recover from the nute lockout, and prepare her for the next stage of her life.
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