Pine trees grow in backyards and other landscapes all over the country, but they can cause a lot of problems for gardeners. It can often be difficult to find plants that can survive, let alone thrive, under pine trees, but fortunately you have a number of options available if you are looking for plants to grow around your pines.
Pine trees can cast heavy shade and often grow in acidic soil. This is partly due to the acidifying effect of fallen pine needles, and partly because pines often grow best in soil that is acidic to begin with. Plants that grow best around and under pine trees should be tolerant both of shade and acidic soil.
Azaleas and Rhododendrons
Perhaps the most commonly grown plants under pine trees are azaleas and rhododendrons. These related shrubs are known for their large, showy flowers, which blossom in a spectrum of colors depending on which varieties you select. These plants not only tolerate acidic soil, but need it and prefer a pH between 5.0 and 5.5. They also grow well in partial shade, though heavy shade is less than ideal. Azaleas and rhododendrons also require well-drained soil, and benefit from the wind protection provided by pines and other trees.
Camellia is another plant that can thrive under pine trees. Janet Carson of the University of Arkansas Division of Agriculture recommends cleyera, aucuba, fatsia, holly and boxwood as potential plants for under pine trees, noting that they are "pretty tolerant" of acid soil. Canby pachistima and creeping wintergreen are groundcovers that do well in shady spots with acidic soil, though wintergreen also needs ample moisture.
Planting shrubs and groundcover under pine trees can cause competition for water and nutrients between the trees and other plants. Supplemental water and mulching can help it this becomes a problem. Also, applying lime will help raise pH, which will allow a greater range of plants to grow under pine trees. This should be done cautiously, if at all, because pine trees themselves seldom thrive in alkaline soil.