Key question. What are the dimensions of your bed? How tall is the lattice?

The bed is about 15 ft long and 4 ft wide/deep. The lattice is about 5 ft tall.

I adore walkers low catmint with my roses , as well as Rozanne geraniums. Gauras as well . You also could post this on the rose forum asking for companion plants and get lots of great ideas . Beautiful area you have and great roses you chose !!

Thanks for your suggestions, Lilyfinch! I've been considering both catmint and geraniums, though will certainly take a look at gauras, as well. Also, thanks for alerting me to the rose forum - I'll try cross-posting over there, too!

Oh, my! Did you really plant 3 Betty Corning clematis there or even one? Do you have anywhere else you can plant her or the roses? Clem BC is an enormous plant, tall and bushy, and will be far too large for that space if you have other plants there. One clematis BC with a groundcover or other perennials might work if you have another spot for the roses. Also, clematis have a difficult time growing on lattice, so you may want to add a trellis or strings or netting to help her climb, something smaller than about pencil diameter. Clematis climb by winding their leaf stems (AKA leaf petioles) around supports, so the lattice usually doesn't work for clematis. BC also gets quite a bit taller than your fence, and would flop over if not given a taller support. I would be worried that the roses will be smothered by her. I grow BC and love her flowers, but she isn't a good match for this space. The green text is a link to the International Clematis Society which has an article about Clematis Betty Corning. It describes Betty Corning as "Vigorous and rather long-limbed, it can put on ten to fifteen feet (3m-4.5m) in a season and achieve considerable volume"

I don't grow any of your roses, but you might want to be sure that they will all fit in that spot if you have somewhere else for the clematis, such as against a large blank wall. There are a large number of smaller clematis if you want recommendations.

For groundcovers, look at Veronica 'Georgia Blue' which is evergreen and has blue flowers in spring along with a few in fall. The most common Stachys, lamb's ears, often has times during the summer when the leaves get unattractive and need trimming back, so I don't think I would use that. I like the suggestion of Geraniums. There are a number of smaller ones that might work, including Geranium sanguineum var striatum (not regular G. sanguineum) or 'Orkney Cherry' and several others that are shorter like those two that will fill in at ground level but that I don't have experience with. Lady's mantle or one of the smaller Nepeta may work, but I think that 'Walker's Low' may be too large for this space as well as it can grow 2'-3' in all directions

By the way, you have a good eye for color combinations.

Thanks so much for your comments, NHBabs - I'm a bit disheartened/frustrated to hear about Betty Corning, as I had contacted Brushwood Nursery prior to purchase, as well as three other independent nurseries, and they all were saying I should purchase more than one! Not sure what to do right now, seeing as all three plants are in the ground and already have some green leafy buds (about an inch high) :/ I unfortunately don't have an empty wall to spare, let alone three, so am feeling a bit down on my luck right now. Any ideas what you would do if you were in my position? I would very much like some greenery behind the roses, so any suggestions you could make for a substitute plant if/when I transplant (or give away) the Betty Corning plants would be appreciated...ugh, and here I thought everything was all good :(

Any way you could make the bed deeper, front to back? If the bed were 8' deep, you would most likely be fine if you could add some metal trellis panels. In the current space, set between shrub roses and I would consider growing one of the non-twining clematis (Integrifolia group) like Arabella, Blue River, Miranda, Mississippi River, or Roguchi. They will be supported by the shrubs and the lattice, but won't get so large that they will be falling over onto the roses. You could try propping or pruning the clematis off of the roses when thy start to get large, but I am not sure that this would work.

Clematis on the Web has a search page where you can type in certain parameters such as height or group and leave the rest blank. You could just put in Integrifolia for group to get a more complete list, though many aren't available in the US commercially, quite a number are.

I am a bit surprised that Brushwood gave you such questionable advice. Did they know how little depth is in the bed and that you were putting other plants as well?

Making the bed deeper is unfortunately the least tenable option right now. There used to be a trumpet honeysuckle vine on that trellis prior to me digging it up, but it was always leggy and thin (not to mention the bright red/yellow doesn't really jive with my color scheme), so I thought clematis would be a good substitute. I really want something that will provide a dense green backdrop for the roses, and the flowers are an added bonus. I gave Brushwood the dimensions of my bed and informed them they would be planted behind some David Austin roses. At the time, I had inquired as to whether I should purchase one or two for the space and they suggested two for "better fill". Would it be worthwhile to write them back?

I was partly convinced that Betty Corning would work in my space having seen photographs like this:

https://static1.squarespace.com/static/59bb0a639f8dce3754a04798/t/5a73b32bec212dd98faa8c14/1519404366306/Clematis+on+garden+gate

Do you think this is possible? I can't imagine that fence is much taller than mine, and the overall look is so lovely.

In your photo, BC is growing up one side and flopping down the other and appears to come out a minimum of a foot and most likely more from the fence on both sides. I think in your bed it will tend to flop onto the roses, but you can give it a whirl to see what happens.

Do a web search for photos of Betty Corning. While some are smaller, quite a number are large and rambling, and that has been my experience with her.

I tend to be a perfectionist about things, but perhaps I'll just throw caution to the wind on this one and see what happens. The rose bushes are bare root, so I anticipate I can keep an eye on BC and still have time/room to move her before they get too big or unwieldy to move around. Thanks again for your thoughts - gardening is most certainly not for the faint of heart!