Ueokishi kimi mo naki yo ni toshi hetaru hana wa waga mi no kokochi koso sure - Kinyo Wakashu(English Translation & Meaning)

植ゑおきし君もなき世に年経たる
花は我が身の心地こそすれ

Roma-ji: Ueokishi kimi mo naki yo ni toshi hetaru hana wa waga mi no kokochi koso sure
English Translation: The one who planted
these trees no longer is here
in this world, and still
the blossoms aging with years
seem to me to be myself
Meaning: In a world where the one who planted it is gone, the flowering tree that has lived on through the years feels to me like my own self.
Commentary: Book Nine Miscellaneous Poems I 518

The one who planted the tree is no longer in this world, yet the blossoms that have gone on blooming through the years seem to the poet like his own self. In the flowers left behind by the one who planted them, he sees himself, surviving the loss of someone dear, and the poem carries a mourner's longing for the departed.
The final line kokochi koso sure is the same as that of poem 528 in this book.

First line, 'ueokishi', means who had planted, the attributive shi of the past ki modifying kimi in the second line.
Second line, 'kimi mo naki yo ni', means in a world where you are no more, showing that the planter has already died.
Third line, 'toshi hetaru', means having passed through the years, the attributive of the continuative tari modifying hana in the fourth line.
Fourth line, 'hana wa waga mi no', means the blossoms are like my own self, joining the flowers left behind with the poet who survives.
Final line, 'kokochi koso sure', means so it feels, the particle koso answered by sure, the realis of the verb su. Poem 528 in this book closes with the same line.
Source: Kinyo Wakashu
Prev Poem: Yamazato mo ukiyo no naka o hanareneba tani no uguisu ne o nomi zo naku
Next Poem: Yukusue no tameshi to kyō o omou tomo ima ikutose ka hito ni kataramu