I need to stop using my phone to initiate posts--here's a photo of the flower:

I wouldn't put this in a pot. It can get as big as all outdoors. And the part next to the ground is the ugliest part of the plant. :-(

Okay, so would you recommend I just completely eradicate it instead?

I also have a small pink jasmine that could go in the pot. I really want to grow a vine up the metal post, cottage garden style.

Well...you can try and see what you think. And not sure which jasmine you mean - if it's true jasmine (Jasminum polyanthum) you wouldn't want that in a pot, either. Vines can be challenging. What about an annual vine like Thunbergia alata, or perhaps a Clematis? They are much better behaved. Most vines would swallow that post whole and keep on going!

Yes, Jasmine polyanthum. You're right they also get pretty crazy and rangey. I think they are so pretty when blooming and smell wonderful. Maybe I'm being naive to think I'll keep it managed--working full time and raising boys!

What about Hardenbergia or Maurandya antirhinniflora? I do like Clematis but this is the front entry area and they look pretty terrible when dormant. I will think about it, maybe I could also grow a trailing evergreen perennial for year-round interest and to overhang the sides a bit.

I'm looking for generally evergreen, climb the post ~4 -5 feet (don't mind maintaining it to a smaller size), full sun, low to moderate water.

I suppose a shrub also work to intertwine the post... Prefer white, pink, or purple flowers... No shrubs are coming to mind, unfortunately.

It's a pot similar to this https://www.allmodern.com/--Clarke-Tall-Fiberglass-Pot-Planter-X111295872-L349-K~A000279518.html?refid=GX433510362858-A000279518&device=m&ptid=940461677016&targetid=pla-940461677016&network=g&ireid=96288517&mktdc=GXPLA&mktcm=739105809&mktst=100248707985&mktcr=433510362858&mkts=%7Bsk%3A%7D&PiID%5B%5D=612276926&PiID%5B%5D=612276924&baseSku=1&gclid=EAIaIQobChMIq4TS8Ynk6wIVzz2tBh1R7wkVEAQYBCABEgJo8_D_BwE

And the front post is black scrolly metal 1960s classic, only one if the scrolls near the bottom had been bent out of shape. It has seen better days but I prefer to repaint it black and grow something up it for a cottage look.

Hardenbergia is probably a better candidate. I think that Maurandya is usually grown as an annual but I have no experience with it. You can always try and see what you think, but that pot does not have a lot of room in it. I gave up on these kinds of aggressive vines because they got too big and messy for my taste.