Dear maid in montana, I have grown all of these for many years and I am sure that cutting back roots and tops is the correct practice for all on your list with one possible exception, the black eyed susan vine(Thurnbergia Alata)If you understand that(most)plants roots and tops are very simular and have many of the same needs, then you know that either roots or top growth multiply their structure by two each time they are cut (pruned)so more roots and more flowers. Lee

I never knew that about roots! If the roots are circling around the bottom should I just pull them off? I usually try to un-circle them but never thought about trimming them! I was afraid I would shock the plant if I trimmed the roots.

I don't cut plants back when I plant them. I want them to bloom aas soon as possible, then I will cut that bloom when it has faded.
By July 1st you won't know which you cut back and which you didn't.
And I would never ever cut back roots unless they were very tightly wound on the inside of the pot or impeding removing the plant from the pot.
Plants need roots to grow stems and leaves......don't cut them off.
Linda C

I always "break up" the roots of bedding plants when I plant them, but I don't trim the plant back (other than deadheading if I feel like it).

I usually make a vertical cut in at least 2 and sometimes all 4 sides of a cell-pack plant (all four sides if the plant is very rootbound). I keep a knife in my planting tools just for this purpose. If the plant isn't rootbound at all, I usually just break the roots up a bit with my fingers as I transplant it.

Cutting or breaking the roots is supposed to stimulate new root growth, just as deadheading will stimulate production of new blooms.

Roughing up the roots and cutting them off are very different. For sure I rough them up, get them out of the form of the pot, allow them to more easily penetrate the new soil...but I don't remove part of the root system.
Plants are built on roots....before any top growth, must come the roots. I don't ever remove any functioning roots when transplanting.
Linda C

I tried something different with pansies and petunias this year. Instead of just watering before I took them out of the flats, I immersed them in water to the top of the growing cell. The plants came out much easier and I had no problem with those tight roots. Immersing the roots made them more flexible so I could easily stretch them out before planting.
Also, when I plant in a container or in the garden, I plant in mud. It is very gentle on the plant roots so I can easily push the plant into the hole.
I learned about planting in mud from Wayside Gardens growing instructions which come with every order.
Vicki H

Planting in mud is NOT a good idea. I believe Wayside says to fill the planting hole with water before putting the plant in, then putting the soil around the plant...not planting in mud. That's called "mudding in" and often packs the soil too tightly around the plants and can tend to smother the root system.
Could you have been reading the instructions for bare root roses?
Linda C