|the internet says stress from the cold and hot and rainy weather has caused this(every other yr they have been beautiful and healthy) what can i do?|
|It's true that yellow leaves can be caused by many things including lack of nitrogen, insufficient light, water-logged soil (plant roots need oxygen to thrive), dry soil, or iron deficiency. If the older bottom leaves are yellow, but new growth is green, it's usually a lack of nitrogen. If new leaves are yellow, with green veins, it's usually a lack of iron. Soil should be kept moderately moist (but not wet). If local challenging weather contributes to their stress, the best thing you can do is continue to maintain yuor roses as you have in previous years (since they were beautiful and healthy). Maintain healthy vigorous plants with good soil and wait out the bad weather! It's best not to overfeed, which stresses the plants. However, if you diagnose from above that it's lack of nitrogen or iron, apply those nutrients according to package instructions. (It should be one or the other, not both conditions.)
Iron chlorosis is recognized by new leaves that are yellow, while the veins remain green. If the condition is severe, the entire leaf may be yellow. Although iron is present in the soil, it is not always in a form that plants can use. Overly wet soils are depleted of oxygen. (As water fills in the minute spaces between soil particles, air moves out.) Plant roots need oxygen to absorb iron in the soil. To help prevent chlorosis, always water slowly, deeply and infrequently and don't irrigate if there's plentiful rain. Iron chlorosis often corrects itself as conditions change. If you are using correct irrigation methods and symptoms are still present, apply iron chelates or ferrous sulphate to the soil. Both are readily absorbed by a plant?s roots. Good luck!