How to hang wrought iron onto stucco wall?

Repairing stucco is expensive. I would get a hose reel box from Home Depot or Lowes and keep it close to the spigot.

maybe this video help...

We have the hose reel box in the back yard because of the dogs, but in front we have a regular hose holder. We didn't want to hang it on the siding, so we purchase a metal post and attached it to that after sinking the post. You could use whatever you want and sink it into the soil if it is sturdy enough to support the wrought iron and hose weight. All a person can see is the hose holder as we sunk it deep enough that the top of the hose holder is at the top of the stake. I hope you can understand what I am suggesting.

Oh yes, attachments pulling out of stucco siding and leaving huge crumbling holes! I've been there.

I eventually abandoned the wrought iron holder before the side wall looked like Woody Woodpecker had a go at it.

My suggestion is to get instead a hideaway hose holder. These are attractive, efficient, and weather resistent. To prevent the box from moving when the hose is cranked in or out, and to keep the holder from sinking down into the wet earth, attach on to large concrete flat blocks.

You could use strong zip ties, or perhaps drill holes if there aren't any on the post. Our neighbor copied the same idea, she has vinyl siding also and didn't want to risk cracking it either. Anything that will save you from cracking or breaking off a chunk of the stucco from the wall. I remember my dad having to do it with the lower part of the wall in the back yard. It wasn't fun for him. I hope it works for you, we like it.