Nanci, welcome to our community. From your photo, it looks like you have a beautiful garden. Your snowball bushes appear to be healthy, so I don't think they are suffering from a nutritional deficiency, nor do they look diseased. I suspect they are a variety which likes to "spread their wings" and fill available space; more like a dome, rather than an upright bush. For the stems near the grass edge, you may want to try staking individual stems higher up towards the bloom, but that would be a lot of work. Sorry I don't have a better idea for you.
