Moonglow Seeds can be found in the Jungle biome by harvesting blooming Moonglow at night. When harvesting Moonglow you will get between 1-3 Moonglow Seeds.
Moonglow Seeds can be planted in Clay Pots or Jungle Grass and grown into additional, harvestable Moonglow. Moonglow Seeds in a Clay Pot will grow anywhere, not just in the Jungle biome. When finished harvesting, the Moonglow will have a sudden burst of light for 2 seconds.