Question
should there be holes in the the bottom of the pot in an annual hanging plant?

Answer
You NEED drainage for these things.  Without drainage, no air.  No air, no aerobic bacteria.  No aerobic bacteria, no roots.  No roots, no plant.  If the summer ends before the plant dies, you're in luck.  If the summer is long, no luck.  End of story.

On the other hand...

That water is messy, right?  It pours out the bottom all over the chairs and deck and maybe even you.

So some people compromise.

The plant goes in a draining pot with holes.  They place it in a hanging basket.  To water, they drench it, then take the basket down and dump the water out.  On a hot day, that water may even continue to soak into the plant.  Some annuals, such as Impatiens, can't take heat and drought; this helps them survive as long as the water is gone by day's end.

But what a pain in the neck, right?  Some people find that too much trouble.  So they take their chances without drainage holes and do their best.  And it often works out.  These people may insist you don't need drainage holes.  It's not quite true; you don't need them if you don't water the plant, or if the plant can take a lot of moisture, or if the dynamics of the airflow and humidity work to keep the soil dry anyway, or if you're one of those people that only waters on Monday.

But some people have a heavy hand with the watering can.  They just have nothing else to do.  They are constantly polishing, and dusting, and vacuuming.  They water water water.  And then you have a plant that drowns.  Those people can't keep anything alive without drainage holes.

That's it.  Yes, and no.  How lazy are you?  Me, I'm very, very lazy.  And impatiens are cheap.  Thanks for writing.

p.s. make sure you have enough LIGHT on the porch to keep flowers coming all summer.

THE LONG ISLAND GARDENER