You can see which part is the front. We will need to choose short plants for the front part, so that we can see the ones behind it. We need medium height plants for the middle, and tall ones for the back. You can tell how tall a plant should get by reading the catalog descriptions. That's the easy part.
Plants come in different shapes, and they also come in different textures.
The textures are fine, medium and bold. It may not be easy to see in the catalog, because we tried to show you the flowers there - but you can still see a bit of the foliage. Those are bold plants. Then some plants have medium leaves, like begonias and dahlias. They aren't big - and they are not small.