Firstly, let us set the cost. Creation of each farming node to get to a final product is 22.588 silver plus an Un'goro Soil (around 10 silver at the time of this writing, being generous); total monetary cost for a node is 32.6 silver (rounded). As for the time cost, it takes 27 minutes for a node to fully mature.
Secondly, the final product. There are four kinds of seeds and each gives two final products. One is similar to foodstuffs obtained through cooking (stamina and spirit buff) and the other is unique to the seed. For example, berries grant 10 Agi whereas melons grant 10 Int. Those do not seem that great, although they could be slightly useful in case they can easily stack with other buffs (e.g. from food).
Still regarding the final product, they cannot be sold to NPCs but can be traded. However, as cited above, their buffs are not that great and require a relatively steep amount of time and money to produce, therefore I doubt someone would wish to buy, let alone for a profitable price. Mind you that the tests above were done at level 60 at 150 survival (in case it scales with survival, I do not know).
On a side note, I would like to point out that I am not considering the Magic Mushroom Spores, as those can only be obtained through NPCs and cost 2g50s each (!). I have only purchased those once in order to complete the gardening quest.
Finally, I would like to present a few directions in oder to improve the system:
- Either make Un'goro Soil optional (as an enhancer) or replace it with something else. Using it conflicts with its use for reputation farming which would require farming to yield much better rewards in order to compete with that.
- Reduce the waiting time to 15 minutes total (5 minutes on each section). 27 minutes is way too long, even as a relaxing activity.
- Improve the buffs provided. At present, the buffs are simply not worth all the investment. I understand that the activity itself is part of the reward but look at fishing, you can get tangible ROI from that activity and gardening could be the same.
- Expand the looting table slightly. It could include some rare drops, be it visuals (gardening gear), pets (bugs), or even something to vendor on NPCs (rare bugs, high quality crop).
- Make the rewards scale with survival if it does not already. In doing so, I would also suggest increasing the survival skill cap to 300.
- Expand the seeds available. I know this is a given, should the system get an expasion in the future, but it would be interesting to also be able to plant herbs and gather them using your herbalism skill. Of course, this could lead to inflation/botting of herbalism but there are many ways to define such system in order to prevent abuse. For instance, it could be an unique 30min CD for gardening and it would work much like existing profession CDs, such as alchemist's xmutes.