In short, don't bother about the faeriebulb seeds drop from harvesting glimmer bulb, these glimmer bulb seeds mostly grown to give sth that are common. And it's not part of the quest.
What we need to focus is to gather piles of seeds, which only come from magic garden, Ivy's hut, FR and conservatories. These are needed for the main quest and to upgrade the maze garden, we need to grow dark seeds from these piles of seeds with glimmer shard/dust to grow random dark plants.