Tell us the direction your porch faces, that would also help. eg. If it's on the north side of the house, the shrubs would need to tolerate shade but on the south side they'd be in the sun. Are there trees near the area you want to plant?
Does the roof shed water onto the bed where the shrubs will be?
How tall do you want your shrubs to grow? Are you looking for a privacy screen, or just a low, decorative easy care border?
Do you want evergreen shrubs or is it ok to have them lose their leaves in winter?
