Answer: Based on your description I am not certain what is happening to your roses.There are many different reasons a rose would defoliate. It might be due to over or underwatering or possibly to a fungal infection, for example. I would suggest you review your overall rose care and see if you can determine what is happening.
In general roses, need a full day or at least a half day of direct sun. They need a location with good air circulation.
The soil should be prepared with ample organic matter and a large planting hole should be dug to encourage good rooting.
The soil should be kept evenly moist but not sopping wet/saturated or dried out. When you water, apply it slowly to the soil -- do not wet the leaves. After watering, wait a few hours and then dig down to see how far the water went. It should be soaking down to the deep roots. It is best to water deeply and less often than to water lightly every day.
Roses can be fertilized with a slow release granular fertilizer per the label directions. Top dressing several times a year with compost will also help feed the soil.
The plants should be mulched with several inches of organic mulch spread out in a flat layer over the root area. This will help feed the soil slowly as it breaks down over time as well as keep down weeds and reduce watering needs.
Roses can be sensitive to sprays such as insect or weed killer, and to overfertilizing. These can cause leaf drop.
Roses can be subject to fungal infections that cause them to drop their leaves. If you suspect a fungal infection, remove all the fallen leaves and put them in the trash. Then apply and reapply a sulfur based fungicide per the label directions. Test spray a few leaves first, wait a few days to make sure it is not causing a toxicity problem, then spray the entire plant.
I hope this helps you trouble shoot.
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