I planted five knockout roses this Spring. One of them is drying up, leaves turning yellow, then brown and falling off. No black spots. Cannot see on other plants. Just a yellow leaf now and then. Should I dig the one bush up or trim it back and hope will come back?
Thanks so much for the photos, it really helps with questions like this. Some rosebushes, even of the same type, react differently to stresses just like people do. The rosebush you sent photos of looks like it is a bit heat stressed. I too have gravel mulch around some of my rosebushes and some of them do just fine with it while others have troubles with the heat generated by it. In you case you have both the heat generation of the gravel mulch and of the brick on your home wall. I suggest pulling the gravel mulch back all around the rosebush about 6 to 8 inches in diameter, forming a circle around the bush. Place some bagged garden soils around the bush and within the new circular area. Cover that with some shredded cedar mulch or pine straw mulch if desired. Water the rosebush with some water that has Super Thrive mixed into the water. Super Thrive is usually available at Wal-Mart or Home Depot, or you can buy it on-line at Amazon or Ebay. Water the rosebush with the same mix the next 5 times it needs watering. That should get it going and relieve the stress. If that does not seem to do the trick, she just may not like that spot. In such a case you would want to take her out and plant a new bush there and see how it does. The other one could be planted in a new location to see how it will do there. I would not trim it back at all yet, the cooler weather coming on can help make them comfortable enough to set on some new foliage for her to gain strength for the winter.