Where are you and growing zone? What are the soi texture and pH, moisture and light levels like? What works in NH doesn't necessarily work in OK or CA or FL or WA or the chalk hills of Dover.

iI you are anywhere near Chicago, check out the Laurie Garden for ideas.

Yes, nearby, though I’ve yet to explore the Lurie garden. I’m pretty certain these plants will all grow here ... I’m zone 5b. This will be in a southern exposure bed, surrounding a culvert, so on the dry side. Not sure about pH levels. I already have the alliums in another nearby spot but the prairie dropseed will be new for me...

1. I know that the Laurie garden has several Salvias and Pycnanthemum/mountain mint, either of which would work in your setting. It might be worth looking to see if they have their plant lists on line for ideas.

You will love the prairie dropseed - Sporobolus heterolepis. It is such an elegant grass. 'Tara' looks interesting and I have only grown the species but you might want to see them both in person before deciding.

I agree with the suggestions made by NHBabs. Salvia 'Schneehugel' is an excellent white.

I have another white salvia on the property (white rain I think) and it’s so long blooming. Will check out your suggested variety too. My challenge is always in getting the mix and layout right. I think the trio of the grass, allium, and a third variety (let’s say the salvia) will give a pretty decent multi season of interest, so I’m good there. but I can’t figure out how to lay them out in the beds for best effect ... they’re both u-shaped beds that wrap around either side of a culvert (separated by a driveway of course). Do I worry about symmetry along both lengths of the u? Do I do batches of three for each variety along the entire u? Or do I mix it up, and do a thread of grass the runs the entire u and then a batch of alliums here and a batch of salvias there? They’re not super deep beds (maybe 3 feet across at widest point of the u) I’m at a stalemate.

Without a photo I can't make arrangement suggestions except to say no rows that run the entire U. At least check out online photos of the Laurie Garden if you can't get there in person. It tends to be planted in drifts. Is there space to make your 3' beds deeper?

Yes pics always help. I would suggest having the Salvia (or whatever) separating the Allium and Sporobolus. The best arrangements always have good contrast in foliage.

I’ll take some pics and send shortly, thanks.

Here is a pic of one of the culverts. So my measurements were a bit off ... it’s an irregular shape but the far side (right) is nearly six feet across, but the left side, near the road, is about three feet ... would love some thoughts on how to arrange the grass, allium, and the third option (maybe white salvia or an aster). I’d like the third plant to be a white option to tie into house trim, which is white. If I’m able to get this bed up and running, I was thinking to extend it so it runs the entire length of the driveway ... but baby steps for now.

This shows it in its entirety

I think a mass planting of prairie dropseed would be beautiful there. I work right across the street from the Lurie Gardens in Chicago and often stop by during my lunch break. They've inspired me to plant more native plantings in my garden and this year, I hope to do plant an edger of this same plant, prairie dropseed, at the foot of my hydrangea paniculatas.

Consider at the lowest levels planting Siberian iris. It is fine in very wet to average soil and has lovely blooms in spring. The midgreen, medium width foliage looks good all season in my garden.

That's a great suggestion.

Ooh, I love the Siberian iris

Look for varieties of Siberian iris that have more buds per stem since they will bloom for a longer time. They are one of my favorite plants, but the bloom season can be as short as a couple of weeks.

I have Siberian iris, Cesar's brother. Are there any others you would suggest?

Bella Rosa, I would ask for favorite Siberian Iris varieties on the perennials forum or the Iris forum.

ok. will do. thx.

I like the old S. iris Butter and Cream because it reblooms again in late summer if the spring flower stalks are cut back. I got Moon Silk which was supposed to be an improved version but it does not rebloom.

Thanks. I'll have to look for that variety.