| Stewartia pseudocamellia | Japanese Stewartia | | Rosaceous & Flowering Trees | Tree < 30 feet, Shrub > 8 feet, Deciduous, Full sun, Part shade, Zone 5b, Requires acid (pH 5.0 to 7.0) |
| Stephanandra incisa | Cutleaf Stephanandra; Lace Shrub | | Low pH | Groundcover, Deciduous, Full sun, Part shade, Zone 5a, Requires acid (pH 5.0 to 7.0) |
| Spiraea x vanhouttei | Vanhoutte Spirea | | Dogwood & Common Shrubs | Shrub 4 to 8 feet, Deciduous, Full sun, Part shade, Zone 3b, Can tolerate acid to alkaline soil (pH 5.0 to 8.0) |
| Spiraea x bumalda | Bumald Spirea | | None Listed | Deciduous, Zone |
| Spiraea x billiardii | Billiard Spirea | | None Listed | Shrub 4 to 8 feet, Deciduous, Full sun, Zone 5a, Can tolerate acid to alkaline soil (pH 5.0 to 8.0) |
| Spiraea tomentosa | Steeplebush, Hardhack | | None Listed | Shrub < 4 feet, Deciduous, Full sun, Part shade, Zone 3a, Can tolerate acid to neutral soil (pH 5.0 to 7.4), Tolerates salt spray |
| Spiraea prunifolia | Bridalwreath Spirea | | | Shrub 4 to 8 feet, Deciduous, Full sun, Part shade, Zone 5a, Can tolerate acid to alkaline soil (pH 5.0 to 8.0) |
| Spiraea nipponica | Nippon Spirea | | Dogwood & Common Shrubs | Shrub 4 to 8 feet, Shrub < 4 feet, Deciduous, Full sun, Part shade, Zone 4a, Can tolerate acid to alkaline soil (pH 5.0 to 8.0) |
| Spiraea japonica (or x bumalda) | Japanese Spirea | | Dogwood & Common Shrubs | Shrub < 4 feet, Deciduous, Full sun, Zone 4a, Can tolerate acid to alkaline soil (pH 5.0 to 8.0) |
| Sorbus x thuringiaca (hybrida) | Oakleaf Mountainash | | | Tree > 30 feet, Deciduous, Full sun, Zone 4a, Can tolerate acid to alkaline soil (pH 5.0 to 8.0) |
| Sorbus aucuparia | European Mountain Ash; Rowan | | | Tree > 30 feet, Tree < 30 feet, Deciduous, Full sun, Zone 3b, Can tolerate acid to alkaline soil (pH 5.0 to 8.0) |
| Sorbus alnifolia | Korean Mountain Ash | | Rosaceous & Flowering Trees | Tree < 30 feet, Deciduous, Full sun, Part shade, Zone 4b, Can tolerate acid to alkaline soil (pH 5.0 to 8.0) |
| Sorbaria sorbifolia | Ural False Spirea | | Flowering Landscape Shrubs | Shrub > 8 feet, Deciduous, Full sun, Part shade, Zone 3a, Can tolerate acid to alkaline soil (pH 5.0 to 8.0) |
| Skimmia japonica | Japanese Skimmia | | Zone 6 & 7 Plants plus shrubs | Shrub < 4 feet, Evergreen, Part shade, Shade, Zone 7a, Can tolerate acid to neutral soil (pH 5.0 to 7.4) |
| Shepherdia argentea | Silver Buffaloberry | | None Listed | Shrub > 8 feet, Deciduous, Full sun, Zone 3a, Can tolerate acid to alkaline soil (pH 5.0 to 8.0), Tolerates salt spray, Tolerates salty soil |
| Sequoiadendron giganteum | Giant Sequoia; Giant Redwood; Sierra Redwood | | None Listed | Tree > 30 feet, Evergreen, Full sun, Part shade, Zone 6b, Can tolerate acid to neutral soil (pH 5.0 to 7.4) |
| Sciadopitys verticillata | Umbrella Pine; Japanese Umbrella Pine | | Pines et. al. | Tree > 30 feet, Tree < 30 feet, Evergreen, Full sun, Part shade, Zone 5b, Requires acid (pH 5.0 to 7.0) |
| Schizophragma hydrangeoides | Japanese Hydrangea Vine | | | Vine, Deciduous, Part shade, Shade, Zone 5a, Can tolerate acid to alkaline soil (pH 5.0 to 8.0) |
| Sassafras albidum | Sassafras | | Maples, Beeches and Others | Tree > 30 feet, Deciduous, Full sun, Part shade, Zone 5b, Can tolerate acid to neutral soil (pH 5.0 to 7.4) |
| Sarcococca hookeriana | Sweetbox | | Zone 6 & 7 Plants plus shrubs | Groundcover, Evergreen, Part shade, Shade, Zone 6a, Can tolerate acid to alkaline soil (pH 5.0 to 8.0) |