Personally I don't think using the Vinca minor would be the invasive problem you seem to think, especially if the variegated form you were intending to use was the "Illumination" form. In any case, other foliage contrast plants that you might consider for this spot in combination with Agapanthus,(and as long as you are being so picky about what you select, I'd recommend against the larger growing forms unless the scale of your garden fountain is large), might include things like Carex morrowii 'Evergold' or Acorus gramineus 'Ogon', Sedum 'Angelina', or perhaps a repeat of the Agapanthus using one of the smaller growing variegated foliage such as Agapanthus 'Tinkerbell' or the similar character of Tulbaghia violacea 'Silver Lace'. I suspect that you would probably object to the last one because of the garlic smell of the foliage, but it is still a great plant for the spot and exposure.

Ceratostigma plumbaginoides could also give you a nice carpet of blue flowers and reddish tinged foliage in late summer/fall to continue the water theme, but this plant does also spread at the roots under favorable conditions, but I don't consider it weedy, just something that may need some editing occasionally if it grows beyond where you want it.

Another low planting choice might include a massed ring of something like Echeveria agavoides 'Lipstick', Echeveria elegans or E. imbricata, Dudleya caespitosa, Sedum palmeri or Kalanchoe pumila.

I can't remember your color scheme, so this might not work with it: fancy-leaf hybrid pelargonium 'Vancouver Bicentennial'. It's sometimes called 'Vancouver Centennial', I think. Green leaves, dark red center, red-orange flower spikes. Nice little mounding plant, about 1'H by 18" width. Easy to find, very well behaved, reasonably xeric; e.g., it might need a little summer water, but not much. Sunny spots are good, it needs a little protection against our coldest weather in the Bay Area.

Thank you so much for your suggestions.

bahia: "Picky"?? I'm not asking him to return a light blue Agapanthus for a dark blue... we just don't want invasive plants. I learned yesterday that moneywort was planted in a small area.... fortunately, a contained area. But since so many have said that even V. minor can be invasive in the right conditions --- and believe me, our clay-soil-on-steriods probably fits that bill -- then I'd like to take the proactive approach and return it before it is in the ground.

jkom51: We have that one elsewhere in a pot.... my husband loves it. In fact I was considering it for this spot.

Thanks again for the nice suggestions.

I love the acorus- it's bright and belongs with water features. I have it in full sun and in partial shade, and it only looks a little ratty in the middle of August in full sun. I have mine planted with blue senecio and aeonium "Swartzkopf" and I really like the effect:

{{gwi:563792}}

Renee

How about iris pallida? It looks like a water plant, but takes very little irrigation.

Here is a link that might be useful: iris pallida variegata

I also thought of Iris Pallida variegata, but hesitated because the foliage shape is so close to the Agapanthus. The color contrast would be beautiful. I can see why the designer chose the Vinca Minor and would probably be willing to give it a try. Al

I agree with bahia.....I seriously doubt Vinca minor would pose much of an invasive threat in your situation. Its invasive properties tend to be focused with woodland situations, where it has the cool, shady, humusy, moist soil conditions it prefers and plenty of room to spread. In more sun, heat and potentially drier conditions, it's sometimes a challenge to get the plant to fill in enough to serve as a good groundcover!

I've grown a variegated Vinca ('Sterling Silver') in my woodsy, PNW backyard for years without problems. I just trim it back when it gets a bit too rambunctious. The white variegation and bright blue spring flowers would be a very nice contrast to the agapanthus.

It's important to remember that any plant's invasive characteristics are NOT uniform in every location or planting situation - what may pose a problem in a east coast woodland garden will not necessarily behave in the same manner in a sunny SoCal location. Most invasive plants are very location-dependent in their behavior.