I agree! I planted a double Knock Out too close to a butterfly bush. The bush grew its normal 8 feet in height shadowing the yellow double Knock Out and it stunted it's growth. I like where it's planted so I keep the butterfly bush more in line by pruning and the Knock Out which gets 6 hours of direct/indirect sun took off like a scalded cat! My rose bush was back. I figured too that it was not enough sun. Knockouts do NOT thrive well in dark shade.
Submitted by pixiesdorule
MY KNOCKOUT ROSES ARE PLANTED IN A SHADY ROW IN FRONT OF MY FRONT PORCH, AND BLOOM BEAUTIFULLY! OUR GROWING ZONE IS 7, OR EAST TENNESSEE. OUR HOME IS ALSO ON A HIGH HILL, THESE ROSES DEPEND ONLY UPON THE RAIN FOR WATER.