What can I use in my flower beds to kill moss that won't harm my plants. I have a really good crop of moss and I am willing to dig it up, but I thought if I killed it first I would spread less spores around.
Mosses like cool, shady and moist conditions, so anything you can do to make the conditions less favorable to them and more favorable to your flowers, (warm, sunny and well drained), will help. It's been a very wet, cool, rainy winter so mosses are doing very well. As temperatures warm up, the sun comes up and the rain lessens they will do less well.
To get rid of moss in your flower gardens, first remove the mosses. They can easily be scraped off as their "roots" are only a means of attachment - they don't grow down into the soil. If you open up the areas to sunlight by pruning overhanging trees and shrubs, you will discourage them. Improving drainage is a big help because it allows the soil to dry out, which flowers appreciate and mosses don't like. Using lime can cause the soil have a more neutral pH. Our soils tend to be somewhat acidic (one reason blueberries and rhodies do so well here). Mosses also like acidic soil. You should be able to easily control mosses using just these physical methods.
If you wish to use chemical controls, iron, ammonium, potassium salts and copper products will deter mosses. Brands like Safer are potassium salts of oils and are organic. Herbicides are not very effective. This article gives good information on Moss and Algae Control in Lawns.