Where is my green going ?

There are several things we need to know about this grow to be able to help so a diary here would be terribly beneficial to both you AND us! You most likely have a lockout of several essential nutrients but the cause of that lockout is a mystery without information so you'll have to be the one figuring it out. The cause could be a lockout because of too much nitrogen (plants in flower need to have the amount of nitrogen reduced and the amount of potassium and phosphorus increased - calcium and magnesium also need to be increased but to a lesser extent).... it can be caused by poor watering practices (usually too little water given so the built-up nutes and salts are not cleared out on a regular basis and would now require a full flush)... it can be caused by not maintaining the pH in a good range (at this stage, it needs to be between 6.0 and 6.5 for a soil grow)... Or it could be the result of all of these factors combined... Aside from those issues, she may just need dramatically more P and K ... I hope you have them on good bloom nutes and I hope you are making sure there's some runoff every time you give plain water and I hope you've got a good pH level at all times... Good luck...