Hi,
I have about 40 clemmies in pots since last spring. Here is what I learned:
Pinch new sprouts. It will stimulate root growth and will give you bushier shape of the plant.
Keep the soil moist, but not soggy. I found that adding moisture crystals to the medium is helpful.
Protect pots from havy rains. Such rains wash out nutrients from pots, plants get anemic. I treated mine with iron after 2 weeks of rains last June.
You can fertilize a couple of times with Tomato or Rose fertilizer. First time now, second time right after blooming.
Alina.

Thanks!