Planting flowers under trees is a method to add additional color and texture to landscapes. Shade-loving flowers can substitute for traditional grass or small bushes in this area of the yard. Add a touch of fragrance to your yard by planting a flower bed with a mixture of plants that offer delicate scents. Check the U.S. hardiness zone where you live and your plants' growing requirements when planting flowers under trees.
Fill the area under the tree out to the drip line with a 10-inch layer of organically enriched potting soil. The potting soil provides a growing area for the flowers without competing with the tree roots for nutrients or water.
Line the potting soil with a garden-edging material. The edging material holds the potting soil under the tree and reduces lawns or other sections of the yard invading the flower bed.
Dig holes in the potting soil area that are twice the depth of the root ball of the flower seedlings and plants. Place one flower in each hole. Cover with potting soil to secure into place.
Lay a 1-inch layer of pine needles for mulch to hold in moisture and keep soil temperature from fluctuating greatly.
Water the area until the ground is evenly moist, but not soggy or saturated.