Answer: These plants are occasionally attacked by fungal infections. These tend to appear when the weather is favorable to them and on plants that have poor air circulation and/or are left with damp foliage at night. It is better for this reason to water in the morning and avoid wetting the foliage when you water. Powdery mildew can actually be washed off (in the early stage) with a spray of water from the garden hose. Generally speaking it is unattractive but should not harm the plant.
Buds can drop for many reasons but the most common are both over and underwatering. Check the soil with your finger to know if you need to water; it should be evenly moist like a wrung out sponge, never sopping wet and never bone dry. I hope this helps.
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