Now find your way across the lawns until you see several numbered greenhouses. Go inside the one labelled "1". Inside, you will meet Professor Sprout, who will give you an assignment: to find yet another one of the ingredients to make Snape's Wiggenweld Potion - a flower named Moly.
6 Pieces of Moly!
Remember Sprout's words: black stem, white flowers.
1. Immediately go to the left, where you will see two spiked snails blocking your way. Their slime trail and body itself will hurt you, but three direct hits (Flipendo) on the snail itself will extinguish it from this world. Pick your way carefully along the grey brick path (you can cast spells over the bricks), avoiding the pitholes - cracks in the ground which become pits. When you see a locked door, use Alohomora on it. Go inside, press the pressure plate and take the Moly.
2. Now go downwards, through bushes and across the bridge you have just turned. Use Flipendo on the block you come across, then proceed downwards once more (past mushrooms), and to the left once you see a gap in the bushes (you should also see a large pit with three bridges, one turned horizontally. Remember this position). Immediately Doxies will attack you, but lure them into the maw of the snapping green monster trapped by mushrooms and get the Moly on the left. Then go to the upper- left and press the pressure plate there.
3. Now proceed right to another bush path, lower this time, and wipe out the thorny bush in your way. Ignore the first path upwards and take the second, right path. Follow that one, pushing Flipendo blocks over chasms until you get another piece of Moly.
4. Now double back to the start, where Professor Sprout is, and this time go downwards. You see the white Puffapod on the other side of the pit? Well, fire a Flipendo and push it along! Then go back upwards to Professor Sprout and go right, past three shelves (remember where they are, I'll come back to that later) until you see a nook in the grey brick walls (just after the three shelves). Go into the nook and fire a Flipendo blast ahead of you, then go back to where you pushed the first Puffapod. See the second Puffapod behind it? Fire a Flipendo from the left (over a grey brick wall) and go to where it rolled. You'll see a third Puffapod. Push it from the front by casting Flipendo over the grey brick wall in front of it. Now with a few more pushes and Flipendos, roll the the third Puffapod onto the pressure plate. It should open a portcullis, allowing you access to another pressure plate and a piece of Moly.
5. Double back to where you saw those three shelves. Search the middle one for another piece of Moly.
6. Remember where you saw those three bridges on the way to find Moly No. 2? Go there, and TADA!! All three bridges are adjoining to form a single long bridge! Cross and get the easy last Moly. Shift the Flipendo block, and from there, go forwards to meet Professor Sprout and Ron.
You and Ron joke about Snape, and then he mentions about a Quidditch match against Slytherin House. Now go back out of the Greenhouse, across the grounds to the right, and find your way to a bannered entrance. Your Quidditch captain, Oliver Wood, quickly gabbles instructions to you as you enter. Remember how you played Quidditch? If not, refer to the section of this Guide, "Quidditch".
After you win (or lose), Ron will congratulate you and tell you to go to the Great Hall for the Halloween banquet, and mentions that Hermione hasn't been around since. Go back into Hogwarts Castle and go right and into the open door.
Go through the deserted passageway and into another door, where the Great Hall is. You converse a little with Ron, and then Quirrell comes in and shouts, "Troll in the dungeons! Thought you ought to know." Ron suggests going to Hermione and warning her about the troll, so exit the Great Hall, through the passageway and QUICKLY past Percy Weasley, who's patrolling very quickly! Now go up the stairs into Floor 1.