As Bill says, softened water is really not good for the plants. In fact, it's toxic. To remove calcium and magnesium in the water, the softener adds sodium. Sodium, as it builds up in the medium, is toxic for plants.
So unless you can get water before the unit, you'll need to find an alternate source of water for the plants!
Bill gave you the link to Ray's site, have a lot at the section 'free information'. There's lots of good stuff there. To save you some searching here's the link directly to the page on
Water Supplies