| K |
| Kadsura, Kadsura japonica |
| Kaffir lily, Schizostylis coccinea |
| Kaleidoscope rose, Rosa'JACbow' |
| Kanuro-zasa; Compact golden-striped bamboo, Pleioblastus auricoma |
| Kardinal rose, Rosa 'KORlingo' |
| Karl Foerster feather reed grass, Calamagrostis x acutiflora 'Karl Foerster' |
| Katharina Zeimet rose, Rosa 'Katharina Zeimet' |
| Katherine Morley rose, Rosa 'Katherine Morley' |
| Katsura tree, Cercidiphyllum japonicium |
| Kazanlik rose, Rosa damascena trigintipetala |
| Keepsake rose, Rosa 'KORmalda' |
| Kentucky coffeetree, Gymnocladus dioicus |
| Kerria, Japanese, Kerria japonica |
| Kerria, White, Rhodotypos scandens |
| Khus Khus, Vetiveria zizanioides |
| Kibo rose, Rosa 'Kiboh' |
| Kiboh rose, Rosa 'Kiboh' |
| King's Flower, Eucomis bicolor |
| Kiss-me-over-the-garden-gate, Polygonum orientale |
| Kiwi Fruit, Actinidia chinensis |
| Kiwi, Actinidia kolomikta |
| Kiwi, Actinidia melanandra |
| Knapweed, Spotted, Centaurea maculosa |
| Knock Out rose, Rosa 'Radrazz' |
| Knotweed, Japanese, Polygonella cuspidatum |
| Knotweed, Pink; Pennsylvania smartweed, Polygonum pennsylvanicum |
| Knotweed, Polygonum spp. |
| Kohsai rose, Rosa 'Kohsai' |
| Kolomikta vine, Actinidia kolomikta |
| Koran evodia, Evodia damiellii |
| Kordes' Perfecta rose, Rosa 'KORalu' |
| Korean feather reed grass, Calamagrostis brachytricha (Calamagrostis arundinacea var. brachytricha) |
| Korean rock fern; Tsu-sima holly fern, Polystichum tsus-simense |
| Korean sweetheart tree, Euscaphis japonica |
| Korean tassel fern, Polystichum polyblepharum |
| Krigia, Mountain; Dwarf dandelion, Krigia montana |