Coastal redwoods (Sequoia sempervirens), the giants of the plant kingdom that grow along California's foggy coastline, are a unique environment for landscaping and gardening. These enormous trees can tower to more than 300 feet tall and grow in U.S. Department of Agriculture plant hardiness zones 7 through 10. On the surface, it seems like planting under redwoods would be a challenging task. However, diverse native flora abounds in redwood forests and points the way to establishing a beautiful landscape beneath these gentle giants.
Select plants that thrive in shade, acidic soil and mild temperatures in both winter and summer.
Pick out a selection of small trees, evergreen and deciduous shrubs, ferns, ground covers, and perennials for planting beneath redwood trees.
Organize the plants with the taller evergreen shrubs closest to the trunks of the redwood trees. Evergreen species with dark green foliage make a nice contrast to the coppery red bark of the trees. Place specimen trees far enough from the redwoods where they can grow to their full size before their branches touch the trunks. Fill in the remaining spaces with a mix of ferns, perennials and ground covers, using flowering deciduous shrubs as accent plants.
Plant in fall, especially if gardening in the native range of redwoods in California. The winter rains in this region help to speed the establishment of a healthy root system.
Plant directly into the native soil under redwoods. Established redwood trees naturally create rich soil around themselves, so it is usually not necessary to use fertilizers or soil amendments with the plantings. Also leave the thick duff of decomposing needles that accumulates under redwoods. This is important to maintaining the soil conditions that keep redwoods healthy and is a great natural mulch to use around the plantings.
Use a spade shovel when planting to slice through the fibrous roots that abound in established redwood groves. Larger roots can be cut with the wide edge of a mattock. Roots that are too large should be avoided by shifting the locations of the plants to areas with pockets of soil that can be more easily accessed. Cutting up small portions of the massive root system of redwoods for understory plantings will not cause harm to the trees.
Water two or three times a week through the summer to provide for the moisture needs of the redwoods and the plants beneath them. The roots of redwoods will soak up most of the water with their extensive mat of roots, so supplying above average moisture to understory plantings is important.
Remove the needles, twigs and small branches that constantly rain down from redwood trees as they accumulate in the branches of shrubs and trees, and can completely cover low-growing plants.