Instructions
Return to Nimbus Land. In the main area with entrances to the palace and other houses, walk along the southeast edge of the clouds until you can walk on an invisible path. Follow the path until you reach the same Shy Away who dropped the seeds after the battle with Megasmilax. Speak to him, and he gives you the fertilizer.
Go to Rose Town from the world map. Upon entering Rose Town, walk Northeast to the Northeastern exit, which takes you to an area with only one house. If you cannot reach this area, go to Monstro Town and speak to the mouse on the second floor of the farthest home from the town's entrance. The mouse speaks about the "geezer" in Rose Town.
Enter the house and speak to its occupant, who automatically sees that you possess the seed and the fertilizer and asks for each. Give him the items, and he proceeds to use the seed and the fertilizer in a large flower pot on his table, causing a giant beanstalk to grow instantly from the table, out his chimney and into the sky.
Climb the beanstalk into the sky, and jump off where it ends onto a platform with two item blocks. Hit each item block for the two "Lazy Shell" items.