Gardening beneath coniferous trees can be problematic. The canopy provides constant shade and the upper layers of the soil are filled with roots. Cedar trees create added problems with their high water needs and dense foliage. Plants growing beneath them often suffer from lack of water and poor light. Perennial plants for dry shade must tolerate little sunlight and moisture, and be adapted to acid soil created by falling leaf litter.
Convallaria majalis (lily of the valley) grows well as a goundcover under cedar trees. Glossy, wide leaves are followed by racemes of tiny bell shaped flowers. The flowers are delicate and fragrant. Convallaria requires watering to become established, after which it is drought-tolerant and one of the more vigorous perennials. It spreads extensively from underground rhizomes, so provide plenty of space for it to grow. Newer cultivars are variegated and some have pale pink flowers. Convallaria majalis is hardy in growing zones 3 through 9.
Epimedium grandiflora (bishop's hat) is a low-growing groundcover that can grow well under cedar trees. New spring growth exhibits red veins and a pinkish flush. Star-like flowers bloom on arching racemes in colors of pink, white, red or yellow, depending on variety. The foliage on some cultivars can be more decorative than the flowers, with a bronze or even purple tint. Epimediums blooms more prolifically with occasional water. In mild climates, this groundcover will remain evergreen. Colder areas will see some die-back during winter. Cutting back the old foliage in early spring will allow the bright, new growth to be seen. Older leaves fade from the startling spring coloration to a dark green. Bishop's hat is hardy in growing zones 5 through 9.
Hostas grow well underneath coniferous trees. They are tolerant of low light and dry conditions. There are many varieties on the market, with multicolored foliage and flowers. Hosta leaves are large and dramatic, adding color and texture to the landscape. These plants can grow up to 4 feet, depending on the specific variety, forming massive clumps. Different varieties planted together in masses brighten up shady areas. Water regularly the first few years for speedy growth. The plant is hardy in growing zones 3 through 8.
Pulmonaria (lungwort) is a small perennial less than 1 foot high and wide. The foliage is splashed with pale silvery green, while some varieties possessing completely silver leaves. Tubular flowers emerge on a short spike in colors of pink, pale blue and purple. They will grow in most soils, and have minimal water needs once established. Cultivars with silver foliage contrast well with dark-leaved epimediums and convallaria.
Platycodon grandiflorus (balloon flower) has unusual looking flowers. Swollen buds resembling inflated balloons open to reveal large, blue, star-shaped flowers. Blooming occurs sporadically throughout the growing season. Flowers are blue, white or pink, depending on the variety. Platycodon is slow to break dormancy in the spring, often beginning growth in late May. Although it's tolerant of dry soil once established, blooming will be more prolific with regular water. This plant should only be divided during the dormant season. Transplanting or dividing actively-growing plants will often severely set them back. Mature plants should not be disturbed at all, for it will most likely kill them. The plant is hardy in growing zones 3 through 9.