How about begonias with sweet potato vine for the green? Both are very easy to grow.

Does the window box have drainage holes? Are you installing auto drip because you suspect the soil is drying out? I would still check the soil daily to monitor the moisture. Too much is no good either.

BTW, pansies fizzle out in the heat of summer so they're not the best choice for all-season color.

Thanks for reply. I did see somewhere potato vines made nice greenery. Yes we have drainage holes. I thought it would be easier to use an auto drip. I was also thinking about trying soil moist

Sounds to me like you need to plant shade loving annuals, and begonias might be the ticket. Most annuals are sun loving, like petunias, so they wouldn't do well in an east facing window box.

It's actually South east