Planting Beneath Evergreens

[calendula]

We have three large spruce trees lining our driveway. I was thinking they'd look nice with some shade tolerant flowers beneath them, but I'm not sure how you plant under trees without damaging their roots. I also wondered if the soil is just going to be too acidic for anything to grow. Has anyone ever had any luck planting beneath spruce or other evergreens?

[Farmfresh]

Most evergreens put out a kind of toxin that repels most plants. Walnut trees are the same way. I know that a very few plants can take the toxin, but honestly I don't know which ones.

[Old Fashioned]

Our next door neighbors have a fir tree that is within just a few feet of our fence line with the branches hanging over into our yard. My garden extends down to this point. Many times when I've been digging in that area I've come across many of it's roots. In that corner that is within 10ish feet of the center line of the tree, about the only thing that has grown is blackberry briars. A few feet in either direction is grass, weeds, etc. One year I did have a small strawberry bed a few feet off to one side, that I also had poked in a few tomatoes. They did okay but not great. I've also tried blueberries, but not so good either.
I've not tried it yet, but Rhodies or Azaleas might be the ticket. In Washington, they grow wild in many of our forested areas. We are called the 'Evergreen State' for a reason but I still wouldn't plant too close.