What types of annuals will do best on a windy balcony? they say that potted geraniums get bashed about pretty badly.

Thanks for advice!

petunias
alyssum
sweet potato vine (which grows more as a trailing plant)
wax begonias
impatiens
vinca vine (which will grow as a trailing plant)
verbena

Probably others over the years...

I think if they are concerned about the plant getting whipped around, they can look for creepers and/or ground cover types, trailers to go around the edge, and low mounding plants (where those would get continually pruned to keep them bushy and low). Something like an ornamental grass, sedge, or the dracena "spike", would give some tall interest in the center of the urn but would be better able to handle the wind.

Avoid petunias unless your elderly relatives want to dead head.