Phalaris is a very abundant grass. There is a couple species of phalaris grass. They grow near ponds and wetlands in large clusters. People commonly mistake phalaris with other types of wetland grasses. You can distinguish the grass by its flowers and vascular pattern. Do some research and find the grass around your area of residence; it thrives nearly everywhere. You can remove the reed with a portion of its roots and re-pot in a wide tray. The plant will spread quickly by large clusters of rhizomes. You can also grow by seed. It should take about 2-3 weeks for harvest from seed.
Then again, after all that is done, you have to extract the DMT. I hate that part. It can be crystalized and smoked, or ingested with another active chemical that reacts with DMT to make it work.