aaarrrrrggghhh!!!

You could try one of those electric fence things where you put a collar on them and put the fence part around your flower bed and when they try and get into your flower it will give them a little shock...although I havenever tried the electric fence thing because I didnt know if it would work or if it did work if it would hurt the dog if the dog got shocked...so you could try it out first like holding it and running it over the fence because if it hurts you it will prob. hurt the dog too....I hope this helps you!

I see you have given a best response, but I thought you still might like another idea. My friend uses old oven racks in her garden to keep her dogs from digging. She puts them on the soil over her bulbs and covers them with mulch so when the dogs start digging they run into the metal rack and can't go any further. She swears it works, although I've never tried it myself.

They know where your favorite plants are and they do it on purpose :) Ok, just kidding! We used to put a thin wire fence around our garden to keep my dog out. It was so thin you could barely see it, but it kept him out!