Except for the abundance of needles and cones, the otherwise barren ground under pine trees can be less than pleasing. A vast genus of trees, pines (Pinus spp.) grow in a wide range of climates, typically in the U.S. Department of Agriculture plant hardiness zones 3 through 9. While the soil near a pine tree is acidic and likely dry, you can create a beautifully landscaped treasure under those trees. You might find the space so enjoyable that you'll want to add a bench or picnic table.
Rake under the trees and set the pine needles aside to use as mulch. Wearing sturdy, garden gloves, discard the cones, trash and other debris. Pull any weeds, including their roots. Or, spray them until they are wet with a ready-to-use, non-toxic herbicide that specifically targets the problem weeds. You can also use a non-selective herbicide, but direct the spray on the weeds to ensure you do not get any other plants wet. Perform this task two weeks before landscaping under the trees so you can reapply the spray in one week's time to kill any surviving weeds.
Cut low-growing limbs to increase sunlight conditions and to gain more room for growing plants. Cut limbs flush to the trunk or to the branch unions from which they grow. Use a pruning saw or loppers, depending on the size of the limbs. Sterilize the tools with a disinfectant prior to use.
Cultivate the soil underneath the pine trees about 8 to 10 inches deep with a tiller, hoe or spade, keeping a distance of about 6 to 12 inches from the trunk. Adjust the depth as necessary when you come across the rare shallow root.
Select plants that tolerate shade and the acidic soil that is created by decaying pine needles. Also, select plants that are drought tolerant, because they will have to compete with the pine trees for water. Ground covers, shrubs, perennials and annuals can work well under pine trees. A well-designed area of a variety of plants might best fit your needs. Examples you might grow include: common yarrow (Achillea millefolium), hardy in USDA zones 3 through 9; and Snow of the Mountain (Aegopodium podagraria), hardy in USDA zones 4 through 9; and ostrich ferns (Matteuccia struthiopteris), hardy in USDA zones 3 through 7. Reminiscent of a redwood grove, ferns banking the base of the pine lend a forest feel, while the flowers add pops of color.
Settle your plants under the pine trees in the same depth as their nursery containers. Allow enough space between plants that they have room to grow to their expected mature width, which varies among plants. Water the area with 1 to 2 inches of water after planting to water both the plants and trees.
Spread the saved pine needles around the plants; stay about 2 or 3 inches from woody stems and trunks. Add additional mulch, such as wood chips, to form a 3-inch layer of mulch, which is sufficient for weed prevention. As the pine needles fall, gently shake the plants and spread them around the garden to maintain the 3-inch layer. Using mostly pine needles as mulch rather than another type avoids the need to clean and remove the needles to get the desired look.