Jersey— they are just roots. Of course you can plant them individually, but for my money thru look best in a “stand” (clump). Mate, I have no idea what your seasons are like there, but you could plant them individually small pots and set them out in , say…May. You could also keep them cool and then plantte roots where you want around the middle of May. Generally speaking, they are very easy to grow and require little attention…unless you want to do a “Chelsea chop” on them or when it is time to break up the clump and make new clumps. We can talk about these things later if you want. The price— I do not know if that is a good price or not, but once you buy them you ought never again to have to buy a phlox again…unless you want a different colour.
So I plant the whole root in the ground, nothing sticking up ? Never heard of just a "root" Roots gotta be connected to something, no? There are no stems to stick out ?
That is correct. The stem will grow and punch through the surface of the soil. There are other plants that are sold this way.