Annuals that would look good in railing planters?

A verbena would work well. Lots of different varieties.
http://www.arhomeandgarden.org/plantoftheweek/articles/Homestead_Purple_Verbena.htm
Alyssum would also work and they smell great. Lobelia also comes to mind.

What’s the light like? What about the climate where you live?

Zone 6, I believe. Tons of light.

I’m having great success with begonias in pots this year.

Begonias

All of the plants in this advert are hardy. I buy different types of these plants each year and throw them in pots all around the place. The marigolds always do well, the begonias and the Dianthus. The Dianthus you need to make sure they aren’t in shade though. The Begonias do okay with more morning than afternoon sun. I am quite sure these aren’t plants you won’t be able to find.

I would if these would work? They’re stunningly beautiful!

Oh my goodness! We are in tune @Mama_Cakes! I would say yes. I have a few pots of them around my gazebo and in pots in the garden and they do look so pretty. I don’t think I have watered them apart from in the first week.

I am starting to believe that we are kindred souls, my friend. :)

:D We are channelling begonias…. :D Okay back to work for me now!

Lobelia

I live in Zone 5. I’ve had wonderful luck with Fuchsia of all colors.
Besides them lasting all summer, they attract more hummingbirds to my yard.

In a sunny spot, fireman red (or deep pink) geraniums, deep blue lobelias and hanging white petunias.

All so beautiful. I am my father’s daughter. He has a love for flowers and so do I. :)