It's a long article, but the part that clicked with me and reminded me of the need for a cold period for once-blooming roses was this paragraph:

For example, the mechanism that controls vernalization and flowering in Arabidopsis thaliana, or thale cress, a plant often used as a model in laboratories, is like a Rube Goldberg device of proteins and gene expression. The plant has a set of genes that create the proteins that cause flowers to form. Before vernalization, the cells are full of a second protein, named FLC, that represses those key, flower-promoting genes. But when the plant is exposed to cold, its cells slow the production of FLC until it stops, and the balance of protein power then changes. The cells start producing more and more flower-promoting proteins, until the plant is ready to burst into bloom. In this case, a simple way to think about this epigenetic action is as a switch. The cold acts as a signal to the cell to switch the way its genes are expressed, from “don’t flower” to “flower, flower, flower.” And even when the cold signal is gone, the switch stays flipped. So, when days lengthen, the plants know it’s the right time to bloom.

There have been threads on this forum that have discussed the need for a certain number chill hours with once-blooming roses, but the way this article explained what's happening with protein combinations / levels inside the cells of the cress plant, and how the cold period affects those proteins, that made it much more clear for me.

It was a great article. Even my DH approved and he "knows" about these things.