- Strobilanthes atropurpureusStrobilanthes atropurpureus
- Strobilanthes rankanensisStrobilanthes rankanensis
- Succisa pratensisSuccisa pratensis
- SundavilSundavil
- Sutera cordifoliaSutera cordifolia
- Symphoricarpos x doorenbosii 'Magical Sweet'Symphoricarpos x doorenbosii 'Magical Sweet'
- Symphytum x uplandicumSymphytum x uplandicum
- Syringa 'Miss Canada'Syringa 'Miss Canada'
- Syringa (Villosae Group) 'Minuet'Syringa (Villosae Group) 'Minuet'
- Syringa meyeri 'Palibin'Syringa meyeri 'Palibin'
- Syringa prestoniae 'James Macfarlane'Syringa prestoniae 'James Macfarlane'
- Tagetes 'Vanilla'Tagetes 'Vanilla'
- Tagetes erectaTagetes erecta
- Tagetes patula 'Harlequin'Tagetes patula 'Harlequin'
- Tanacetum coccineum Tanacetum coccineum
- Tanacetum coccineum 'Robinson's Rose'Tanacetum coccineum 'Robinson's Rose'
- Tanacetum partheniumTanacetum parthenium
- Tanacetum Vulgare 'Golden Fleece'Tanacetum Vulgare 'Golden Fleece'
- Teucrium chamaedrysTeucrium chamaedrys
- Teucrium scorodaniaTeucrium scorodania
- Thalictrum 'Anne'Thalictrum 'Anne'
- Thalictrum aquilegifoliumThalictrum aquilegifolium
- Thalictrum aquilegifolium 'Thundercloud'Thalictrum aquilegifolium 'Thundercloud'
- thalictrum delavayathalictrum delavaya
- Thalictrum delavayi 'Album'Thalictrum delavayi 'Album'
- Thalictrum flavum 'Elin'Thalictrum flavum 'Elin'
- Thalictrum flavum ssp. glaucumThalictrum flavum ssp. glaucum
- Thelypteris palustrisThelypteris palustris
- Thermopsis lanceolataThermopsis lanceolata
- Thuja orientalis aurea nanaThuja orientalis aurea nana
- Thujopsis DolabrataThujopsis Dolabrata
- Thymus 'Mountain Select'Thymus 'Mountain Select'
- Thymus 'Purple Beauty'Thymus 'Purple Beauty'
- Thymus citriodorus 'Lammefjord'Thymus citriodorus 'Lammefjord'
- Thymus polytrichus ssp. britannicusThymus polytrichus ssp. britannicus
- Thymus praecox 'Highland Cream' Thymus praecox 'Highland Cream'