It seems you would like to save them. Your best chance to reinstate root development would be to layer the bottom of the holes with 2" of milorginite. Then place the roses in. Then use a fill of milorginite/potting soil. A 50/50 mix. Then top off with 1/2 inch of milorginite. Be sure not to bury the crown. Make sure the crown can breath. Then use drip irrigation and adhere to strict proper watering amounts. Probably an inch per week. Overhead irrigation will cause leafspot and weaken recovery. I'm not a rose expert. But this is the best I got. Knockout roses are hardy. Good luck.
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