I have poppies (Beauty of Livermore) and lots of delphiniums in my perennial garden. They overlap just slightly. Late poppies with early delphiniums. I would just love for all of them to bloom together. Is there a way to get the poppies to bloom later or the delphiniums to bloom earlier?
In The Well Tended Garden, the author prunes in a way to delay flowering in several types of perennials. She has experimented enough to be able to say what works and what doesn't... It might be a book worth looking into.
Yes, that's it. I wrote from memory, I am not in the house where the book is at present. It's a great reference, I find, especially when she lists a particular plant I'm looking for help with. She's done a lot of experimental pruning, with varied results.