How do I get my pink flowers off the ship?

In order for its flower value to count, decoration in storage must be placed on an island.

Open the storage, either by tapping on the storage ship or by holding down anywhere on the island until the green arrow fills. Tap on the decoration you want to place, and it will auto-select an open space on your island. But you can move it where you'd like. You should see a green glowing base, which means the space is clear of obstructions. A red base means there is an obstruction, so you cannot set it there. Set the decoration down by tapping on it again or by tapping on the green check button at the bottom.