Mittsu Shima (Three Islands) includes rocks, a stone lantern, three islands in a sea of granite, Japanese maples and selected conifers, collectively form an Asian landscape in this Northwest garden.
| Botanical Name | Common Name |
| Abies concolor ‘La Veta’ | La Veta White Fir |
| Abies grandis ‘Van Dedem’s Dwarf’ | Van Dedem’s Dwarf Grand Fir |
| Abies nordmanniana ‘Hunnewell Broom’ (‘KBNG WB’ |
Hunnewell Broom (KBNG Witches Broom) Nordmann Fir |
| Acer palmatum var. dissectum ‘Inaba shidare’ |
Inaba shidare Lace-leaf Japanese Maple |
| Acer palmatum var. dissectum ‘Viridis’ | Green Lace-leaf Maple |
| Acer shirasawanum ‘Autumn Moon’ | Autumn Moon Shirasawa Maple |
| Calluna vulgaris ‘Allegro’ | Allegro Scots Heather |
| Calluna vulgaris ‘Anouk’ | Anouk Scots Heather |
| Calluna vulgaris ‘Bradford’ | Bradford Scots Heather |
| Calluna vulgaris ‘County Wicklow’ | County Wicklow Scots Heather |
| Calluna vulgaris ‘Dark Beauty’ | Dark Beauty Scots Heather |
| Calluna vulgaris ‘Firefly’ | Firefly Scots Heather |
| Calluna vulgaris ‘Fritz Kircher’ | Fritz Kircher Scots Heather |
| Calluna vulgaris ‘Galaxy’ | Galaxy Scots Heather |
| Calluna vulgaris ‘Goldsworth Crimson’ | Goldsworth Crimson Scots Heather |
| Calluna vulgaris ‘Kinlochruel’ | Kinlochruel Scots Heather |
| Calluna vulgaris ‘Perestroika’ | Perestroika Scots Heather |
| Calluna vulgaris ‘White Coral’ | White Coral Scots Heather |
| Calluna vulgaris ‘Wickwar Flame’ | Wickwar Flame Scots Heather |
| Calluna vulgaris ‘Winter Chocolate’ | Winter Chocolate Scots Heather |
| Campanula carpatica | Tussock Bellflower |
| Campanula poscharskyana | Serbian Bellflower |
| Campanula x ‘Samantha’ | Samantha Bellflower |
| Cedrus libani ‘Green Prince’ | Green Prince Cedar of Lebanon |
| Cerastium tomentosum ‘Snow-in-Summer’ | Snow-in-Summer Dusty Miller |
| Clematis x ‘Stasik’ | Stasik Clematis |
| Clematis x ‘Yukikomachi’ | Yukikomachi Clematis |
| Cornus alba ‘Ivory Halo’ | Compact Variegated Red-twig Tartarian Dogwood |
| Cornus alba ‘Kesselringii’ | Black-twig Tartarian Dogwood |
| Epilobium canum | California Fuchsia |
| Erica carnea ‘Bell’s Extra Special’ | Bell’s Extra Special Winter Heath |
| Erica ciliaris ‘Mrs. C. H. Gill’ | Mrs. C. H. Gill’s Dorset Heath |
| Erica cinerea ‘Hardwick’s Rose’ | Hardwick Rose Twisted Heath |
| Erica cinerea ‘Lime Soda’ | Lime Soda Twisted Heath |
| Erica cinerea ‘Purple Beauty’ | Purple Beuaty Twisted Heath |
| Erica cinerea ‘Velvet Night’ | Velvet Night Twisted Heath |
| Erica tetralix ‘Pink Glow’ | Pink Glow Cross-leaved Heath |
| Erica vagans ‘Kevernensis Alba’ | Kevernensis Alba Cornish Heath |
| Erica x darleyensis ‘George Randall’ | George Randall Darley Heath |
| Erica x darleyensis ‘J. W. Porter’ | J. W. Porter Darley Heath |
| Erica x darleyensis ‘Mary Helen’ | Mary Helen Darley Heath |
| Erica x darleyensis ‘Silberschmelze’ | Silver Melt Darley Heath |
| Erica x darleyensis ‘White Perfertion’ | White Perfection Dale Darley Heath |
| Euphorbia cyparissias ‘Fens Ruby’ | Fens Ruby Cypress Spurge |
| Gentiana acaulis ‘Holzmann’ | Holzmann Stemless Gentian |
| Hamamelis x intermedia ‘Arnold Promise’ | Arnold Promise Witch Hazel |
| Ophiopogon planiscapus ‘Nigrescens’ | Black Mondo Grass |
| Picea abies ‘Pusch’ | Pusch Dwarf Norway Spruce |
| Picea glehnii ‘Chitosemaru’ | Dwarf Glehn’s Spruce; Dwarf Sakhalin Spruce |
| Pieris japonica ‘Bonsai Andromeda’ | Dwarf Variegated Pieris |
| Pinus heldreichii ‘Smidtii’ | Eugene Smidt’s Dwarf Bosnian Pine |
| Pinus mugo ‘Amber Gold’ | Amber Gold Mugo Pine |
| Pinus mugo ‘Wintergold’ | Wintergold Mugo Pine |
| Pinus sylvestris ‘Hillside Creeper’ | Hillside Creeper Scots Pine |
| Podocarpus alpinus ‘Blue Gem’ | Blue Gem Alpine Plum Yew |
| Podocarpus lawrencei ‘Purple King’ | Purple King Mountain Plum-Pine |
| Rhododendron x ‘Alexander’ | Alexander Evergreen Azalea |
| Rhododendron x ‘Johanna’ | Johanna Evergreen Azalea |
| Rhododendron x ‘Joseph Hill’ | Joseph Hill Evergreen Azalea |
| Rosa x ‘America’ | Climbing Rose |
| Rosa x ‘Bill Warriner’ | Floribunda Rose |
| Rosa x ‘Crysler Imperial’ | Hybrid Tea Rose |
| Rosa x ‘Grand Prize’ | Floribunda Rose |
| Rosa x ‘Johann Strauss’ | Floribunda Rose |
| Rosa x ‘Lemon Zest’ | Shrub Rose |
| Rosa x ‘Opening Night’ | Hybrid Tea Rose |
| Rosa x ‘Queen Elizabeth’ | Floribunda Rose |
| Rosa x ‘Scentimental’ | Hybrid Tea Rose |
| Rosa x ‘Sheila’s Perfume’ | Floribunda Rose |
| Rosa x ‘Showbiz’ | Floribunda Rose |
| Rosa x ‘Sixteen Candles’ | Floribunda Rose |
| Rosa x ‘Sundance’ | Hybrid Tea Rose |
| Rosa x ‘Tamora’ | English Rose, Austin Rose |
| Rosa x ‘Voodoo’ | Hybrid Tea Rose |
| Santolina virens ‘Lemon Fizz’ | Lemon Fizz Green Lavender Cotton |
| Taxus baccata ‘Repandens Aurea’ | Golden Spreading English Yew |
| Thymus pseudolanuginosus | Woolly Thyme |