investigating swick next... thanks!
Emilya - Ok first off, stop "flushing" - this will simply KILL your plants and make things much worse.
There's science and physics at work below the soil line that NOTHING humans can do to change that fact.
The 2 words the dispel the "flushing" thing are:
Cation Exchange
Here's a popular link that dumbs it down enough for me to understand.
Cation Exchange Capacity in Soils, Simplified
Basically the "nutrients" in your soil are held in place at the roots with a positive or negative charge - Water is H2O there's noting in the water that attracts any anions or cations from the nutrients. Water goes in and water runs out - nutrients are already attracted to and attached to roots/humus/soil. Better to transplant into new soil than "flush". I've transplanted into new soil at flip and even 2-3 weeks into flower with no ill effect. Usually for me to do that the reason is root-bound pots and that shows the ugly head as the plants start to change.
Every once in a while I get this issue with yellow leaves right in the beginning of flower.
What I do is make alfalfa tea with some EWC added in and top water in. Foiler spray 2-3 times a day with Kelp meal tea strained and sprayed on.
Kelp meal tea will pretty much fix any deficiency in the soil. At the end of the run I dump that soil and usually go to a larger No-til pot and re-mix the soil starting over if you will but in a larger container. I've found that my 5gal pots will show this after say 5-6 rounds even with amendments added.
That or cull the plant... sometimes genetics are what they are. It's really not worth my time to spend another 8-9 weeks nursing a plant to the end when I can just go grab another one in VEG and replace the one plant that is missing the ball with another one. I just did that last week... chop chop easy come easy go. Some plants are not worthy, usually we see that in VEG early on as seedlings, see something not quite right - toss and move on. I of course do not do that when I've got a plant full of flowers already. It sounds harsh but long haul it's better and I find it hard to do but get over it.
Kelp meal tea - I cup added to a gallon of water let steep or bubble overnight. Take 1-2 cups of that and dilute with another gallon of water - strain and foiler spray and or water in. I find that foiler works pretty much right away.
Some folks, me included will amend soil at flip from VEG to flower as well.. Nothing beats a 1/2 cup of alfalfa meal, calcium (CaCO3) or some sort of liming agent (oyster flour), kelp meal and a bit of Neem cake meal... and a cup or 2 of worm castings for the win!
To reference where "Flushing" comes from. It's from folks that grow in soil-less medium or more specific hydroponic systems. Somehow for some strange reason flushing made it's way into the soil medium indoor growing as did a lot of other "science".
All that said above - there are strains that actually yellow a lot and loose fan leaves all the way from flip to chop. I'm growing one and have been for some time. I don't stress about yellow unless it's the whole plant AND it happens fairly quickly. Say 1 week of flower and the plant is a pale green... something is wrong and I get either the pruners or the sprayer and kelp meal out. It's for sure something going on in the soil tho.