Yorozuyo to sashite mo iwaji sakurabana kazasamu haru shi kagiri nakereba - Kinyo Wakashu(English Translation & Meaning)

万代とさしてもいはじ桜花
かざさむ春し限りなければ

Roma-ji: Yorozuyo to sashite mo iwaji sakurabana kazasamu haru shi kagiri nakereba
English Translation: Ten thousand ages,
I will not set such a bound,
cherry flowers,
for the springs we wear you in our hair
will know no end at all
Meaning: I will not set a limit and say ten thousand ages, for the springs in which we wear cherry blossoms in our hair will go on without end.
Commentary: Book Five Celebration Poems 309

Since the springs in which cherry blossoms are worn in celebration will go on without end, the poet will not set a bound by saying ten thousand ages. Setting aside even 'ten thousand ages' as too limited, the poem celebrates an eternal reign. With sashite meaning both to specify and to insert a flower in the hair, it is tied to kazasu, to adorn the hair.
Following the double cherries of the preceding poem, 308, it sings of cherry blossoms, and while it names ten thousand ages as poem 306 in this book does, it treats even those ages as having a limit.
From poem 305 through poem 310 in this book come poems celebrating a thousand and ten thousand ages through such things as bamboo, the spring of Iwashimizu, pines, cherry blossoms and the poet's own self.

First line, 'yorozuyo to', means as far as ten thousand ages, the same word as the first line 'ten thousand ages' of poem 306 in this book.
Second line, 'sashite mo iwaji', means I will not set a bound and say, a pivot word in which sashite means both to specify and to insert a flower, left in kana, with the negative volitional ji. The poem breaks after the second line.
Third line, 'sakurabana', is the cherry blossom, taking up 'eightfold cherry flowers' in the preceding poem, 308.
Fourth line, 'kazasamu haru shi', means the springs when we will wear them, shi being an emphatic particle; it is tied to the inserting in the second line.
Final line, 'kagiri nakereba', means since there is no end, giving the reason for the second line.
Source: Kinyo Wakashu
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