Hi Jeanne,

That is a great question, and a few factors come in to play.

In general, yes you can grow plants beneath pines without any problem.  You'd want to be sure that the plants were shade tolerant and that you did not damage the trees' roots while you were planting; smaller plants at the time of planting would be best.  You will also need to provide supplemental water in most cases, as the tree canopy limits rain from reaching the ground beneath it and the tree is going to be quite good at capturing whatever precipitation does reach the ground.

You would not need to worry about "acid soil" beneath the pine; the idea that pine needles acidify the soil is not true.

Depending on where you live, though, another consideration is that you do not want to add "ladder fuels"--plants and/or shrubs that could carry a wildfire from the ground into the treetops--beneath pines or other evergreens.  If you live rurally or near open space, you would want to limit plants beneath pine trees to things that stay short (lower than 6") and make sure that the tree is limbed up to at least 6 feet (or 1/3 the tree's height if it's still a small tree).

I hope this is helpful!

Cordially,

John