1) On the table in the room with the Vita-Chamber and U-Invent station..
2) In the ceiling above the first big daddy shortly after you start. You'll have to lure the Big Daddy away from the door with Target Dummy, and then freeze him with Winter Blast. Once he's frozen, you'll have to jump on top of him, and then jump up and grab the rose.
3) Using the pressure switch, back at the beginning by the first big daddy. When you step on the pressure switch after the room with the turrets, you'll have to run back to the first room. A small panel will drop down on the side of the platform next to where you first entered the room.
4) Use the grenade launcher to blow up the middle rpg turret. You have to go to the beam to be able to reach. The rose will be found after you search the destroyed turret.
In case a visual is needed, here's a video that I found on YouTube that'll help.
*This is not my video. Credit for the video goes to 0verlord73.