Simon Bamboo Variegated 'Singing Sixteen' Daylily
'Single Red' Hybrid Peony 'Sioux Falls' Coral Bells: sanguinea
'Sirius' Daylily Sisi
'Siskin Clock' Carnation: Dianthus 'Siskiyou Blue' Idaho Fescue
'Sissinghurst White' Jerusalem Cowslip 'Six Hills Giant' Catmint
Six Week Grass 'Sizzler Burgundy' Scarlet Sage: splendens
'Sizzler Lavender' Scarlet Sage: splendens 'Sizzler Lilac Bicolor' Scarlet Sage: splendens
'Sizzler Mix' Scarlet Sage: splendens 'Sizzler Salmon' Scarlet Sage: splendens
'Skeleton Key' Foamflower: Tiarella 'Skippy XL Red-Gold' Horned Violet
Skullcap Skullcap, Bushy Blue
Skullcap, Pink Skullcap, Pink Texas
Skullcap: suffrutescens Skunk Cabbage
Skunk Cabbage: foetidus Sky Flower: grandiflora
'Sky Magic' Garden Petunia Sky Pilot 'Purple Rain'
Sky Vine 'Skyline Neon Lights' Garden Petunia
'Skyline Purple Haze' Garden Petunia 'Skyracer' Tall Moor Grass
'Skyrocket' Alumroot: Heuchera 'Skyrocket' Rockcress
Sleepydick Slender Amaranthus (spp.)
Slender Amaranthus 'Viridis' Slender Blue Flag
Slender Spike Rush Slender Verbena (spp.)
Slime Lily Slipper Flower 'Cinderella Mix'
Slipper Flower 'Cinderella Red' Slipper Flower 'Cinderella Yellow with Dots'
Slipper Flower: crenatiflora Slipper Flower: falklandica
Slipper Orchid 'Agincourt' Slipperwort
Slipperwort: falklandica 'Sly-Jenna' Florist's Chrysanthemum
Small Crowfoot 'Brazen Hussy' 'Small Gesture' Daylily
Small Globe Thistle (spp.) Small Globe Thistle 'Taplow Blue'
Small Leaf Sage (spp.) Small Leaf Sage Dwarf
Small Leaf Sage Golden Small Leaf Sage 'Icterina'
Small Leaf Sage 'Purpurea' Small Leaf Sage 'Rachels Gold'
Small Leaf Sage 'Sage Of Bath' Small Leaf Sage 'Tricolor'
Small Leaf Sage 'Variegated Berggarten' Small Leaf Sage 'Woodcote'
Small Woodland Sunflower Smallage
Small-Flowered Century Plant Smartweed (spp.)
Smartweed 'Speciosa (Firetail)' Smartweed 'Taurus'
Smartweed, Pennsylvania Smartweed: capitatum
Smartweed: emodi Smartweed: polymorphum
Smartweed: virginianum (spp.) Smartweed: virginianum 'Compton's Form'
Smartweed: virginianum 'Lance Corporal' Smartweed: virginianum Variegated
Smilax 'Smokey Rose' Alumroot: Heuchera
Snail Bean Snail Vine
Snake Aloe Snake Palm (spp.)
Snake Plant (spp.) Snake Plant 'Laurentii'
Snake Plant 'Moonshine' Snake Plant: zeylanica
Snakebeard Snakeberry
Snake's Head Iris Snakeshead Fritillary (spp.)