For 50 years, ever since he came to the US, Ruby has risen before the sun to stock his stand; now, when he arranges produce in ``perfect pyramids,'' Suny Ho and his little sister admire his artistry and ask how it's done; and when Ruby's wife, Trudy, asks, ``Is it time?'' she doesn't just mean time to get up in the morning: she hopes he'll honor his promise to retire to the mountains. When Ruby falls ill, Sun Ho's family pitches in with the shop and does such a fine job that it helps the old man, once he's well, to agree that ``It's time.'' Winter's jewel-bright cityscapes are composed with an affectionate care equaling Ruby's with an array of top-quality vegetables. An appealing, nicely formed story—whether it's the passage of generations, cultural transition, or fruit, ripeness is all. (Picture book. 4-8)