In attempting to understand the nature and cycle of a Cannabis plant, many conclude that knowing when a plant is finished is easily seen by watching all of the plants changes, which include; buds are no longer are swelling. Pistils have receded and have turned orange. Trichomes are cloudy/amber via a certain percentage. The strain's approximate flowering cycle in weeks. Leaves have/are turning yellow.
I believe a grower can see when a plant is ready by watching all of these "Signals", without even using a special scope to see when the Trics are a certain color, as Tric color can be seen with the naked eye. But the key is, making sure the plant is "Done".
Now, my real purpose of starting this Thread is to discuss the yellowing of leaves. I have talked to growers who feel that keeping fan leaves green all the way up to harvest is good and that yellowing of leaves at this stage is not the best for a maturing Cannabis plant.
I have done research on this subject, and the Cannabis plant in the wild can tell us something about how she will finish out her life during the final stages of maturity. In the wild, Cannabis will die at the end of Flowering, so the seeded buds can drop into the ground for the next natural grow. This seems logical as we all know that Cannabis didn't come from our Grow Room/Closet.
We also should consider that Cannabis in the wild does die, and the leaves will turn yellow during maturity. I've watched many growers, including myself, become nervous when leaves begin yellowing during the last 2-3 weeks of Flowering, wondering if we over/under-nuted. I'm not so sure that this "Stress" is warranted, as we are simply watching what Cannabis does in the wild, and, this is a firm signal that our plant is entering the final phase of Flowering.
Trying to maintain green leaves all the way and into the final stage of Flowering seems to not only be unnatural, but also confuses a grower to when the plant is actually finished, as this is an important signal to know when to cut our plant(s) down. We also see some comparison to this when we watch Fall colors change our plants/trees during a certain time of year, letting us know the firm signal of a season via a plants color change.
It appears that a Cannabis plant will begin to digest the sugars/proteins/nutrients left over in the green leaves and this is what helps the buds develop fully in potency, size, and readiness. This also gives the grower confidence in the plants development and the time when she is really ready for Harvest.
Just some thoughts of mine...peace GM