I suppose you are referring to the type of topiary that are lined with moss and filled with soilless mixes. In which case you can plug low creeping plants, enough to cover the frame. There are several types that are referred to as steppable plants. Shade loving plants are - Ajuga comes to mine, creeping speedwell, lamium.

Thanks Ianna. I had actually never heard of making topiaries that way, but that opens up a lot of possibilities.

Creeping jenny (Lysimachia numularia) is another that does well in moist part shade. You could have fun with that as a topiary because it comes in all shades of green, including a bright chartreuse that would wake up a shady area.

Thanks, Cady. I looked up creeping jenny and it's really pretty. I also confirmed it's not poisonous. So that may be what I'll use. I'll have to see if our nursery has it.

You can buy it online, too. It's a popular groundcover.