Adverstised as competition for Limelight (and probably Little Lime too) but more compact; size-wise it is in between those two, closer to LL:

http://www.gardendebut.com/plant/Royal-Star-Silver-Dollar-Hydrangea

http://www.waysidegardens.com/silver-dollar-hydrangea/p/37448/

Still new-ish. Claim to fame is 5-6' tall and wide (Little Lime is advertised 3-5'). Not sure if the blooms' shade of white and lime is like Limelight's or not. Little Lime is a little off white than Limelight. Put it anywhere a paniculata would be work. Part or full sun in northern areas and give it afternoon sun protection in the extreme South. It won an RHS Medal so it might be a good choice.

It's been around a while, but not caught on as much as some others. I don't remember where you are, but if you are in the midwest, the Chicago Botanic Garden published an evaluation in 2011 that included Silver Dollar. They rated it 3/5, but none 5/5, perhaps since their alkaline soils tend to create chlorosis. Not included are the newer varieties such as Vanilla Strawberry, Strawberry Sundae, and Bobo.

Here is a link to the summary, and here to more detail as to the different varieties they tested and why they rated them as they did.

Thank you both for this information. Just curious...

I have two SD, they are fantastic, just gorgeous. The flowers are huge, plants are covered in blossoms, they are like Lime Light, when blooms go from lime to white to pink. I like them as much as my Vanilla Strawberry or maybe even a little better. They just produce much more blooms than VS. They are about 4’ tall. My soil is alkaline.

I noticed the blooms are flopping. Do you recommend using supports (there are some things in the picture that look like wires but I was not sure)?

They can be floppy. The blossoms are huuuge - the length of the biggest VS blossom and very full. and when it rains they get heavy. So I tie them up. My plants are not old, this is their second summer, so I am not sure what will happen when they get older.

I was also considering planting some Silver Dollar Hydrangeas, but I was also concerned about their floppiness when in full bloom. Many of the photos I have seen show the plant with flopping stems when in bloom. I like Ruby Slippers Oakleaf Hydrangea a lot, but I was concerned about brown spot, which many oakleaf hydrangeas in my area seem to be susceptible to.

My RS is near a cercospora infested mac. It gets water from the drip irrigation and has not caught leaf spot yet. Neither have other nearby macs and paniculatas. To minimize the chances, try doing no overhead watering and throw in the trash any dry leaves/flowers/plant debris from an infested plant. If you use a sprinkler, run it around dawn to minimize problems caused by leaves that get/remain wet for long time periods (the sun will help evaporate moisture in the leaves).