I would suggest something that has a rich, dark red flower like Tuscany Superb's color. Unfortunately TS doesn't repeat bloom & its bloom cycle doesn't match Limelight's, so you are going to have to look for a repeater with similar color that grows well for you in your area. I would make sure that the red rose has no orangish or pinkish tones to it.

Here is a link that might be useful: Tuscany Superb hmf picture

I would go with a white floribunda or shrub rose, making sure that the white matched the limelight white when it is in that stage. That would make for a formal look--if you like formal looks. Would be quite stunning on moonlit summer nights.

I think I'd try Munstead Wood, a deep red Austin with wine tones, as a companion. I can't get that out of my mind right now, but other color combos would work beautifully, too, like a rose pink. Diane

Mmmm, another vote for a deep crimson, and also add in some slashes of lime (molucella, bupleurum, Bowles golden grass, hakenochloa) and deep pinks (Ruby Wedding astrantia, knautia macedonica).

Thank you so much for your suggestions. I had considered roses with wine tones such as Munstead Wood. I noticed that a volunteer seedling of Brazilian verbain next to the limelights looked really good and that gave me that idea.

The all white roses is a great idea, one that has been stuck in my head now, thanks hoovb!! :-) I think a white rose with a "milky" tone to it might work well. I would think the "snow" white roses would look to bright white next to the more milky hydrangea blossoms.

I am not sure how pink tones would look planted next to the hedge. One of my first thoughts were some of the English roses that have pink and also yellowish tones like Jubilee Celebration... on the other hand, I walked past a flower show where they had deep red roses combined with lime-ish colored filler plants and it looked modern and fresh...

What are your thoughts on something like Lady of Shallott or a warm pink like Princess Alexandra of Kent in groups of several plants each on front that hedge?

I have PAK and I think the color would work well as long as the Princess didn't get too tall. Mine is a year old and is about 5 feet, but in your cooler climate, she might stay shorter. Her color is a bit variable, too--at least here. In the heat, there are more warm tones, and when it's color, she's more of a straight pink, but not a light one. What about the new Austin in a medium pink called Boscobel? (Hope I got that name right). That rose's look has got me enthused about Austin's again. Here's a pic of PAK with less of the yellow tones in her coloring. Diane