I use what I've found to be extremely effective yet safe way to fight slugs. It's a substance known as iron phosphate, commercially known as Sluggo (among other brand names). It's harmless to your pets and supposedly provides your soil nutrients as it decomposes. It works very well for me, especially if applied early in the season. The link below is to one site selling it, though I bought the BIG jug of it. Good luck.

-Ray

Here is a link that might be useful: Iron Phosphate Link

Thank you so much Ray! Mid season here....still worth a try I'm sure. Since I intend to enjoy Dahlias for many years to come Sluggo will become part of my process. This is kinda funny, Sluggo was my nick name when I as a kid.

If anyone else knows of other treatments I'd sure like to know about them.

I also endorse Sluggo - it saved my dahlias from complete destruction by slugs when the bulbs were just pushing up through the ground. In one 24 hour period, my dahlias were reduced to stubs, and I had to dig them up, replant and cross my fingers that they'd come back. After one treatment of the Sluggo, the slugs disappeared overnight. The bulbs are doing well, and it looks like I'll have blooms. As a backup, I also put out dishes of beer, and yes ... it worked exceptionally well. I'm sure you won't need to use the backup, but I was so desperate to save my dahlias that I was willing to try everything. Coffee grounds, beer, Sluggo. Best of luck!

Slugs just ate all my zinnia seedlings 2 weeks ago, so I bought the same thing (I think it is a different brand, it is called "Slug Bait" but the active ingredient is the same: iron phosphate + bait. It is very effective.

You can get it from Home Depot of Lowes.

Beside the "Slug Bait" on the rack, there were also Slug Killer." I think that one is stronger but is more dangerous as the label says "not to be used around children."

I don't have children, but I like something milder, so I chose the Slug Bait. I found it VERY effective.