Hi linjarvis,
Love your views of rockgarden. They are awesome! Read what plants you have in there but you are missing Sempervivums (hen and chicks) and other Sedums for extended blooms
Delosperma cooperi
Delosperma nubigenum
Sedum Matrona blooms late summer and fall
Sedum Stardust
All are succulent plants. The Delospermas are groundcovers that bloom all summer
Just my 2 cents worth.