There isn't enough information to suggest a probable cause based on what we actually know about the plant's recent care, but based only on the odds, a recent change in light from brighter to dimmer and/or over-watering in the not too distant past would be the likely cause(s), either individually or collectively. Al

the plant is about 10 feet away from an east facing window. I have not felt it for dryness but I water it when the top leaves look droopy. The plant has drainage. I have not given it fertilizer. The plant is fairly new to me. I bought it a few months ago from lowes. Based on your comments, I can try to move it closer to the window. Thank you.

I'm thinking underwatering for the pots is the culprit, although overwatering can also cause the yellow leaf symptoms, though usually not so quickly here. Agree with Mad, going with heat stress & find it nearly impossible to overwater a potted rose in active growth as long as the pot size is adequate, the potting mix good & drainage holes functioning. Like Valrose, potted roses here are watered at least once a day & often twice when the day temps get to 80 & above. I water each one & then go back & water each again to make sure they're thoroughly watered each time. If we get a soaking rain, I skip the watering. Hot days after cooler ones increase water needs here. And it's not only the warmer temps, but the greater intensity of sunlight every year that affects plants whether potted or planted. In the last few years, plants that were formerly happy in part sun part shade conditions have needed more shade as well, which I also chalk up to the intensity cranking up. With such frequent watering of pots, I subscribe to the "weakly weekly" fertilizing routine, using Neptune's Harvest liquid at half rates for larger plants & quarter rates for younger ones, on a second watering of the day. A good bit of rain usually falls here year round, with cloudbursts & storms frequent over the growing season. Though the land is clay based loam, the roses were never more lush & happy than a recent Summer when storms came by daily. Agree with Mad here again, in those circumstances, even with the soil saturated to puddles, no roses (or other plants) seemed to mind at all. What we see as red pigments in rose leaves, such as apparent in new leaves, actually protect the leaf by dissipating heat. Mildew can be brought on by underwatering in heat here, but it's opportunistic, does't bleach leaves & treated by washing the leaves with water wand & making sure the roots have adequate water. Occasionally see older leaves bleach out quickly right ahead of or at the same time as a growth spurt occurs. Just some random thoughts over a late lunch break & likely not well organized, but hopefully food for thought. Are your pots protected from heating up in the sun? I'd water the pots a good bit more, the planted out roses too, and start them on the Neptune's once satisfied their water needs were met daily. The Neptune's also great as a foliar spray applied in early evening when the temp's below 75 & leaf stoma open to absorb it completely. Sue

New growth isn't a clear indication that the plant is growing. True growth is measured by a plant's increase in dry weight; so, if a plant is shedding a leaf and growing a leaf, it's roughly in a static state, which is not a good place for a plant to be. I'm not necessarily saying the leaf ISN'T being shed as a result of normal senescence, only that new growth might not indicate an o/a increase in mass. There is no better fertilizer program than one you can control to the degree you know exactly what nutrients your plant is getting, how much of each, and when nutrients will be available for uptake. There is an ideal level of nutrients in the soil and an ideal fractional amount of each in comparison to each and all of the others. Most plants use about 10X as much N as P, and about 3/5 as much K as N. The rest of the nutrients also have an ideal level determined by a function of N levels and the overall level of total dissolved solids (TDS) in the soil solution. Adding tonics, miracle concoctions, or supplements targeting an increase in 1 or 2 nutrients w/o good reason or a strong likelihood what you are doing is going to correct a deficiency, is far more likely to result in limitations than benefits. Al