And here's a post by the legendary Oldtimer1:
A plant needs to build as large a rootmass as possible from an early stage, this gives sturdy plants full of vitality, this is why when growing in compost we recommend starting in small pots and as soon as the compost is full of roots pot on to a larger pot. By doing this in stages until you reach the final pot size you maximise the root mass for any given final pot size. You get many times the root mass you would if you planted a small cutting/seedling in a final pot. Once the plant goes into flowering mode it uses the roots it made to build the parts needed to reproduce its self, if the roots are inadequate for the job the plant will sacrifice parts of its self to make the reproductive parts.
Out of interest another problem with planting small plants in final pots, is the plants roots only occupy a tiny portion of the compost, so the unoccupied part tends to become anaerobic inhibiting new growth and encouraging the multiplication of pathogenic fungi and bacteria, the larger the pot the worse the problem.
In the early days of cannabis growing indoors stoners tended to try and grow like this as its easy and its what you would do if you were planting outdoors in soil, well as we have said compost is not soil, its a medium that is made to act in place of soil in an enclosed container. The early books on cannabis growing answered the problem by advising that the compost was mixed half and half with perlite, rather than the practice of potting as used by the horticultural industry world wide. So the myth still abounds today in the cannabis world today, that cannabis needs loads of drainage. Its not true.
HS the symptoms you are are seeing, are of a plant in decline, stripping all the elements out of the old leaves from the bottom of the plants sunleaves. Its something you do see anyway, but not to your extent and as early. It means the plant as a whole is not receiving enough nutrition. Its ability to do so comes from several things, 1.] that it has sufficient root mass, 2.] that the root mass is given adequate nutrient for the plants needs 3.]assuming you have an adequate root mass, that the planting medium is making the nutrients available to them. The final thing, low temperatures will arrest root development, neither the root ball or the ambient air temperature should never drop below 16c.
HS if you used the potting on method I still suspect your problem stems from a compost problem. I know Arnie uses potting on as when he first used it reported back on it and how much better it was, again his symptoms point to a compost problem.
ie he says nothing has changed but he is seeing weak and slower top growth in early veg, this has to be poor root development. Strong root development and maintaining a healthy root mass give a sturdy top structure. A good fresh compost should give this without any additions apart from water.
