The Manor System is linked to the region ruled by Castles and thier Lords. The clan owning the castle can set up prices for seeds that will be sold at the Manor Manager NPC in towns in that castles region. These seeds can be matured through a process similar to spoiling and sweeping and the end results can be used as currency at the Castle Blacksmith to buy items such as Quick Healing Potions and other useful items.
How it works:
If the castle has their manor system set up you can go purchase the seeds and a Harvester at the Manor NPC from towns in the castles region. Each seed has a specifc level range, those seeds must be used on the monsters from that castles specific region and the seeds level and the monsters level must be similar.
The way to level up (mature) the seeds is very similar to spoiling/sweeping. You use the seed on a monster to "seed" them, there will be a message in the chat window saying whether or not the seed was successful, if not, use it again till its successful. Next kill the monster and then you use the Harvester on the monsters dead body. (keep in mind that if that monsters level is too far away from the seed level it can fail to harvest) When using the Harvester you will gain a new version of the seed you used, a more matured version. This more matured version can be turned into the Manor NPC by clicking "Settle Special Products" option then click the crop you want to sell and click "sell" and in exchange you will get crafting materials (they only accept a certain quota per day).
Then the castle owner will get the final most matured version of your seed that you turned into the manor manager inside their clan warehouse a day later. The most matured versions are used as currency at the Castle Blacksmith found in every castle to get several different items such as Quick Healing Potions.
*Note: Keep in mind that Quick Healing Potions (QHP) reuse time here is longer then retail due to balance reasons, rather then the instant reuse to prevent spamming (which is subject to change).
*Also Quick Healing Potions are blocked in events.