I thought I saw a recent answer that if you cut back lupins they don't bloom so well next time round. The lavender. Why not trim it back a few inches and dry off the trimmings in paper bags to make a pleasant perfume in your wardrobes or drawers. Then tie some garden string or straw tie around the plant to support itself. If you cut back too far into lavender it may not like it.

The first flowers of the season on lupins are always the best, but cutting off the dead flower heads promotes the plant to produce more, but slightly smaller, flower spikes. Cutting the dead heads off lavender might make the bush flower again later.