schwartzwalders are gorgeous!
don't put taro in the same pot, it's very vigorous and will choke the calla. mine are in 8" pot. but mine are white and much smaller. yours can probably take a 10" pot. depends on how many rhizomes you got. i had 3, but they did not bloom the 1st year. may be i planted them too late.

Am planning to start them indoors in a few weeks and put them out once it gets warm outside. Thanks for the info abt the Taro.