To me, there is indeed a pragmatic understanding, in that you need to feed the soil to grow good vine/plants again and again. That the plants and trees need water and a rich dark soil to grow well, and that every few years it is good to let the soil rest.
The fact an surnatural growth will lead to an early exhaustion of the soil is not something that could have been part of the medieval paradigm, as this is not something that can be observed or deducted. Some plant will exhaust the soil faster, but only because it is their nature to do so, the abnormal rate of growth should not have an impact on the nature of the plant (light or heavy feeder)
To me, when the spell is cast on a plant, the nature and quality of the environment will tell the end product :
If the seedling is set in a rich soil, with room to grow and in a sunny spot, with an amount of water matching its needs, it will grow big and tall. If some or all of these elements are missing, it will grow the best it can in such environment.
The soil would not degrade as all it does it to host plants and as it has been fed properly once a year, it is a great soil, that is the "natural behavior"
The water will not be sucked out dry, as a rain shower every few days is enough to keep the soil wet enough to grow plants.
For plants to grow properly they must be planted in a place exposed to some degree of sunlight, the actual exposure of the plant during its growth does not seems to be a factor (it can grow overnight) so I would say that if the spot is suitable, the plant will grow well.
That would indeed lead to an incredible industrial potential, but that's magic, so of course it is ^^ The restrictions, if you want to set some, would be more appropriate if they come from the side effects : meddling with mundane, jealousy > Can be seen as a miracle from your end, but pure witchcraft from another one, and if you do start flooding the regional market with high quality timber, dirt cheap... I can definitly see a demon enjoying this to spread some Diabolic taint over the region ^^