This location is not accessible on disc 4
You can find Edea's House on the world map as soon as Balamb Garden is mobile, but you won't be able to enter or identify it. After the events at Trabia Garden, coming back here will produce a hint that something big—namely, Galbadia Garden—is nearby. You still won't be able to enter, but this does set off the end sequence for disc 2.
On disc 3, you'll be able to visit Cid and Edea here. After doing so, visit Rinoa in the infirmary of Balamb Garden. When you do, you will be taken to your first Laguna flashback in some time, in Trabia Canyon.
After the flashback, return here and speak to Edea to get a Letter that will help convince the White SeeDs to help you.
When you come here later at Rinoa's request, follow Angelo once you enter.
On disc 3, you'll be able to visit Cid and Edea here. After doing so, visit Rinoa in the infirmary of Balamb Garden. When you do, you will be taken to your first Laguna flashback in some time, in Trabia Canyon.
After the flashback, return here and speak to Edea to get a Letter that will help convince the White SeeDs to help you.
When you come here later at Rinoa's request, follow Angelo once you enter.