Here's your Evergreen Pouch that you'll need to use the Tharlendis seeds with. You also need to have Un'Goro soil samples on hand to use as fertilizer for the seeds. Just use the pouch when you have everything; the pouch will take care of the rest.
When you have enough morrowgrain, bring them to me here on Elder Rise. Please don't bother the Arch Druid; he'll be very busy with the research, as well as the multitude of concerns he has!
Yes <name>, have you grown some morrowgrain for the Arch Druid's important research? The mysterious properties of Un'Goro Crater become clearer with each passing day, thanks to the help you are giving us.