I'd give the plant at least 4 weeks before feeding. And I'd go light at
first. The risk here is that the nitrogen will burn the young feeder roots,
which is not so good. Some say after the first bloom. Right now water is
the most important thing. Some every day or so. Nothing you do will make
the first flush outstanding, but if you avoid stressing the roses by feeding
too soon, the root systems will establish, and by mid summer you'll be glad
you went easy.

Next year, you can start feeding soon after new growth appears and every 6
weeks there after until 6 weeks before the first hard frost of fall is
scheduled.

Gook luck

Jeff, Southeast Michigan, Zone 5


I have a follow up. You posted that I shouldn't use granular food
when planting a bare root rose. How long after the rose has been
planted can I begin to add the food?

I use the Bayer 2-in-1 Systemic Rose fertilizer, but they indicate you
can place it in the ground at planting. I want to get the roses off
to a good start, but I really want to also have some color this year
too.