Quote Originally Posted by Some Random Source
Vegetative Growth


Seedling
The formation of the second pair of leaves begins the seedling stage. They are set opposite each other and usually have a single blade. They differ from the embryonic leaves by their larger size, spearhead shape and serrated margins. With the appearance of the next pair of leaves, each leaf usually has three blades and is larger still.



A basic pattern has been set. Each new set of leaves will be larger, with a higher number of leaves per blade until, depending on variety, they reach their maximum number. This is usually seven leaves per blade, but may be as many as nine or eleven leaves. The seedling stage is complete when the plant has reached this maximum leaves per blade, usually within four to six weeks.






Vegitative
This is the period of maximum growth. The plant can grow no faster than the rate that it's leaves can produce the energy required for new growth. Each day, more leaf tissue is created, thereby increasing the plant's capacity for growth. With excellent growing conditions, Cannabis is known to grow as much as six inches a day, although the rate is more commonly one to two inches.



The number of blades on each leaf begins to decline towards the middle of the vegetative growth stage. Then the arrangement of leaves on the stem (phyllotaxy) changes from the usual opposite to alternate. The internodes (stem spaces between sets of leaves, which had been increasing in length) begins to decrease, and the growth appears to be thicker. The vegetative stage is usually completed in the third to fifth month of growth.
Hope this helps.