Fireblossom Seeds

Fireblossom Seeds were introduced in the 1.0.5 patch.

They can be found when harvesting Fireblossom, but only when the plant is in lava. Only a blooming Fireblossom plant will yield seeds when harvested, and the only way to make a Fireblossom plant bloom is to literally pour lava on it. The easiest way to do this when attempting to procure your initial seeds out in the Underworld is to place blocks two high on either side of the plant and then pour a Lava Bucket into the gap, thus submerging the Fireblossom in lava. Now, when you harvest the Fireblossom, it will also drop Fireblossom Seeds.

Fireblossom Seeds can be placed in empty Clay Pots or in Ash Block and grown into additional, harvestable Fireblossom. Potted Fireblossom will grow anywhere, not just in the Underworld, but will only yield seeds if you submerge the plant, Clay Pot and all, in lava. Yes, Clay Pots are somehow immune to lava.

Keep in mind as of 1.0.5 you can no longer harvest flowers or herbs out of Clay Pots with a standard bladed weapon; instead, use your Pickaxe and left-click on the flower or herb above the Clay Pot you wish to harvest out of.