Planting in the fall can work too, so I decided to go ahead with planting the rest of the garden: the part-shaded part to the north of the building.
I did things a little differently: primarily, I planted more densely by creating a matrix on 12-inch centres of three types of grasses. Within this matrix, I planted the forbs. I also added a couple of shrubs for a structural element.
The rough planting plan is at the top of this page.
Here is a list of the plants
Bottlebrush grass (for the most shaded part)
Nodding wild onion
Wild strawberry (arguably this could be part of the matrix layer. I am testing it out)
Serviceberry x 2
While I was making this order, I ordered extra to fill in gaps on the main planting. I also ordered 5 Butterfly milkweed to add to that part of the garden, as well as two shrubs: smooth rose.