| Hostaname | RG | SZ | Leaf color | P | F | Origin |
| H. 'Kabitan' Maekawa/AHS 1987 | R | | ch,dgre | | | sieboldii sport |
| H. 'Kabuki' Greg Johnson 2004 | R | M | gr,crwe | | | ('Neat Splash' x 'Northern Halo') x 'Hadspen Blue' |
| H. 'Kaitlyn' D. & J. Ward 1998 | R | | gr,cre | | | 'Pin Stripe Sister' hybrid |
| H. 'Karen' B. Olson 1999 | R | | blgr,we | | | ('Crepe Suzette' x 'Blue Moon') sport |
| H. 'Karin' Gerard Heemskerk 2005 | R | ML | dgr,crwe | | | 'Anne' sport |
| H. 'Kasseler Gold' Heinz Klose/P. & J. Ruh 2003 | R | L | goy | | | 'Semperaurea' hybrid |
| H. 'Katherine S. Mahoney' S. Chamberlain 2006 | R | | gr | | | unknown |
| H. 'Kathleen' Frances Williams/Connie Williams 1986 | R | M | gr | | | unknown |
| H. 'Kathy-O' O'Donnell 1994 | R | M | str | | | 'Undulata Erromena' sport |
| H. 'Katie Q' M. Zilis 2003 | R | M | blgr,ye | | | 'Marilyn' sport |
| H. 'Katrina Jo' F. Nyikos 1998 | R | M | gry | R | | 'Spritzer' hybrid |
| H. 'Kayak' G. Black/P. Ruh 1999 | R | 9 | blgr | | | unknown |
| H. 'Keepsake' L. G. Jones/Tony Avent 2007 | R | | gr,ye | | | 'Fascination' seedling |
| H. 'Kelsey' H. Kelsey/F. Williams 1968/P. Ruh 1996 | R | S | dgr | | | unknown |
| H. 'Kenzie' Ken Harris 2007 | R | S | gr,crwe | | | 'Neat Splash' seedling |
| H. 'Kerplunk' Herb Benedict/P. & J. Ruh 2005 | R | M | y>gry | | | 'Kabitan' hybrid |
| H. 'Keuka Kiss' P. Brandt-Sorheim/M. McElwee 2002 | R | | dgr | | | 'Francee' x 'Francee' |
| H. 'Keuka Love' M. McElwee 2002 | R | | blgr,(ly>bl)e | | | 'Love Pat' sport |
| H. 'Kevin Kelley' Goodwin 1996 | R | ML | gry | | | 'Sum and Substance' hybrid |
| H. 'Key Lime' Pauline Banyai 1990 | R | M | lygr | | | montana hybrid |
| H. 'Key Lime Pie' H. Hansen 2003 | R | | gr,goe | | | 'Squash Casserole' sport |
| H. 'Key West' Olga Petryszyn 1999 | R | | goy | | | 'Elatior' x 'High Noon' |
| H. 'Ki Nakafu Otome' Japan/M. Zilis 2003 | R | | (gry>gr),gre | | | unknown |
| H. 'Kifukurin Hyuga' Japan/P. Ruh 2002 | R | M | dgr,(y>w)e | | | unknown |
| H. 'Kifukurin Ko Mame' Japan/P. Ruh 2002 | R | DS | gr,cre | | | unknown |
| H. 'Kifukurin Ubatake' Japan/P. Ruh 2002 | R | D | gr,cre | | | unknown |
| H. 'Kilauea' E. Elslager 2001 | R | | str,gr,cr | | | 'Sea Prize' x 'Maekawa' |
| H. 'Kilowatt' Maxine R. Armstrong 1970 | R | S | gr | | | nakaiana hybrid |
| H. 'Kinbotan' Japan/P. Ruh 2002 | R | D | gr,na(y>gr)e | | Y- | venusta hybrid |
| H. 'Kinbuchi Tachi' Japan/P. Ruh 2002 | R | M | dgr,(y>cr)e | | | rectifolia sport |
| H. 'Kind of Blue' D. & J. Ward 1999 | R | | blgr | | | unknown |
| H. 'King Croesus' Alex Malloy 2003 | R | | gry,mot | | | 'Bold Ruffles' hybrid |
| H. 'King David' S. & S. Zolock 2001 | R | | blgr | | | hypoleuca hybrid |
| H. 'King James' G. Krossa/A. Summers/P. Ruh 1992 | R | XL | gr | | | montana hybrid |
| H. 'King Lizard' F. Rogers 2003 | R | | dgr | | | 'Niagara Falls' x 'Grand Canyon' |
| H. 'King Michael' G. Krossa/A. Summers/P. Ruh 1992 | R | VL | gr | | | montana hybrid |
| H. 'King of Spades' D. & M. Beilstein 2007 | R | 9-10 | dgr | | | 'Neat Splash' x 'Blue Moon' |
| H. 'King of the Hill' E. Elslager 2005 | R | G | gr,str,lgr,goy | | | 'Galaxy' seedling |
| H. 'King Tut' Gretchen Harshbarger 1981 | R | SML | ch>y | | | 'Tokudama Aureonebulosa' hybrid |
| H. 'King's Black Knight' H. King 2006 | R | | dgr | | | 'Grand Master' seedling |
| H. 'King's Ransom' D. Dean 1999 | R | | gry | | | 'Sun Power' hybrid |
| H. 'Kingfisher' Eric B. Smith/BHHS 1988 | R | M | bl | | | tardiflora x sieboldiana 'Elegans' |
| H. 'Kingwood Center' Kingwood Center 1993 | R | M | y,dgre | | | (x 'Frances Williams') sport |
| H. 'Kinki' Japan/P. Ruh 2002 | R | L | y | | | unknown |
| H. 'Kira' L. Maroushek 1999 | R | | blgr | | | unknown |
| H. 'Kissing Cousin' E. Elslager 1998 | R | | dgr,cre | | | 'Wide Brim' sport |
| H. 'Kit Kat' D. Smetana/A & D Nursery 1994 | R | | lgr,blgre | | | 'Love Pat' sport |
| H. 'Kite' Eric B. Smith/BHHS 1988 | R | | blgr | | | tardiflora x sieboldiana 'Elegans' |
| H. 'Kitty Hawk' R. Herold 2000 | R | | y | | | 'Sum and Substance' hybrid |
| H. 'Kiwi Black Magic' B. Sligh 1999 | R | VL | dgr | | | sieboldiana x ventricosa |
| H. 'Kiwi Blue Baby' G. Collier/B. Sligh 1999 | R | SM | bl | | | 'Halcyon' selfed |
| H. 'Kiwi Blue Flash' B. Sligh 2000 | R | M | str,bl,gr,y | STR | | 'Blue Cadet' sport |
| H. 'Kiwi Blue Ruffles' B. Sligh 1999 | R | L | blgr | | | sieboldiana 'Elegans' selfed |
| H. 'Kiwi Blue Sky' B. Sligh 1999 | R | SM | blgr | | | 'Blue Skies' selfed |
| H. 'Kiwi Blue Sunrise' B. Sligh 1999 | R | L | blgr,ye | | | sieboldiana sport |
| H. 'Kiwi Canoe' B. Sligh 1999 | R | S | blgr | | | 'Blue Cadet' selfed |
| H. 'Kiwi Dreadlocks' B. Sligh 2000 | R | | mot,gr,y | | | 'Tokudama' hybrid |
| H. 'Kiwi Emerald' G. Collier/B. Sligh 1999 | R | M | dgr | | | 'Halcyon' selfed |
| H. 'Kiwi Forest' B. Sligh 1999 | R | L | str,blgr,cr | | | 'Tokudama' sport |
| H. 'Kiwi Full Monty' B. Sligh 2000 | R | M | (gry>y)c,blgre | | | 'Striptease' sport |
| H. 'Kiwi Gold Rush' F. Jury/B. Sligh 1999 | R | ML | gr>y | | | unknown |
| H. 'Kiwi Gold Star' B. Sligh 1999 | R | M | goy | | | 'June' sport |
| H. 'Kiwi Hippo' L. Phillips/B. Sligh 1999 | R | M | ygr>gr | | | hypoleuca x longipes |
| H. 'Kiwi Jordan' B. Sligh 2000 | R | M | blgr | | | unknown |
| H. 'Kiwi Kaniere Gold' B. Sligh 1999 | R | L | ygr | | | 'August Moon' sport |
| H. 'Kiwi Milky Way' B. Sligh 2000 | R | XL | bl | | | 'Sagae' hybrid |
| H. 'Kiwi Minnie Blue' B. Sligh 1999 | R | | bl | | | sieboldiana x sieboldiana |
| H. 'Kiwi Minnie Gold' B. Sligh 1999 | R | D | ch>y>cr | | | 'Floradora' hybrid |
| H. 'Kiwi Pacific Blue' B. Sligh 1999 | R | XL | bl | | | sieboldiana selfed |
| H. 'Kiwi Parasol' B. Sligh 1999 | R | M | blgr | | | 'Sparkling Burgundy' sport |
| H. 'Kiwi Spearmint' B. Sligh 1999 | R | S | w,gre | | | 'Undulata' sport |
| H. 'Kiwi Splash' B. Sligh 1999 | R | | str,dgr,y,cr | | | 'Francee' sport |
| H. 'Kiwi Sunlover' B. Sligh 1999 | R | L | ch>(grc,ye) | | | 'August Moon' sport |
| H. 'Kiwi Sunshine' B. Sligh 1999 | R | M | ch>y | | | sieboldiana x 'Tokudama' |
| H. 'Kiwi Tease' B. Sligh 2000 | R | | (gr>y),crwe | | | 'Striptease' sport |
| H. 'Kiwi Treasure Trove' H. Redgrove/B. Sligh 1999 | R | L | gr,crwe | | | 'Fortunei Aureomarginata' sport |
| H. 'Kiwi Waves' B. Sligh 1999 | R | | bl | | | 'Sagae' selfed |
| H. 'Klaus von Klitzing' G. Braun-Nauerz 2003 | R | | gr,dgre | | | unknown |
| H. 'Klopping Variegated' Klopping/Peter Ruh 1988 | R | M | dgr,we | | | 'Fortunei' sport |
| H. 'Knickerbocker Holiday' Alex Malloy 2004 | R | | | | | (x 'Torchlight') selfed |
| H. 'Knights Journey' Alex Malloy 2002 | R | | dgr,crwe | | | 'Chivalry' sport |
| H. 'Knockout' Paul Aden 1986 | R | SM | gr,cre | | | unknown |
| H. 'Ko Mame' Japan/P. Ruh 2002 | R | D | lgr | | | unknown |
| H. 'Ko Seto' K. Watanabe/P. Ruh 2002 | R | | gr | | | unknown |
| H. 'Kokuryu' T. Kurasawa/T. Nakayama/P. Ruh 2000 | R | M | lgr | RB | | unknown |
| H. 'Komodo Dragon' Mildred Seaver/Charly Seaver 2004 | R | G | gr | | | 'Donahue Piecrust' seedling |
| H. 'Koneko' R. Olson 1999 | R | | str,blgr,w | | | unknown |
| H. 'Kong' Clarence Soules 1990 | R | XL | blgr | | | sieboldiana hybrid |
| H. 'Konkubine' H. Klose/P. & J. Ruh 2005 | R | | lgr | | | unknown |
| H. 'Korean Snow' K. Hawks/Bob Solberg 1999 | R | | str,lgr,y | | | yingeri hybrid |
| H. 'Krinkle Sister' E. Elslager 2005 | R | L | y,blgre | | | 'Krinkle Twist' sport |
| H. 'Krinkle Twist' E. Elslager 2005 | R | L | blgr,ye | | | "'Dorothy Benedict' F1" sport |
| H. 'Krinkled Joy' Arett/Armstrong/AHS 1986 | R | SL | blgr>dgr | | | unknown |
| H. 'Krista' B. Olson 1999 | R | | blgr,ye | | | (x 'Dorothy Benedict') sport |
| H. 'Krossa Broad Band' Gus Krossa/Peter Ruh 1991 | R | ML | blgr | | | unknown |
| H. 'Krossa Cream Edge' G. Krossa/P. Ruh 1997 | R | SM | lgr,cre | | | unknown |
| H. 'Krossa Regal' Gus & Alma M. Krossa 1980 | R | ML | gagr>dgr | U | | nigrescens hybrid |
| H. 'Kuk's Concoction' E. Elslager 1999 | R | | str,dgr,y,bl | | | 'First Impressions' hybrid |
| H. 'Kyoto' H. Sugita/P. Ruh/J. Ruh 2001 | R | | gr | | | aequinoctiiantha x pycnophylla |