Looking for a flower, not a shrub, preferably perennial, that actually has a scent for our roof garden. We can't have more weight than what is there so it has to be from seed or or a plant already started. Most flowers have had their fragrance bred out of them which has to be among the great mysteries of our time, but there must be a few esp among the heritage plants. Any suggestions?
If fragrance is recessive with a particular group of plants then it disappears on its own, instead of being intentionally removed during artificial hybridization.
Although it's not a perennial (but I have had some that has overwintered), you could try throwing some sweet alyssum (Lobularia maritima) seeds up there. It is a hardy annual, small mounds of flowers, very fragrant, and always self-sows for me.