No mints of any kind, ever.

Sedums are good, they have shallow roots. Just don't let them crowd the stems.

Actually, I was going to ask the same question so I'll just tag along instead of starting another thread.
Anyone try Heucheras?

the area is in open shade. At about three ft is is full sun, for the clematis, though. It is also surrounded, so invasiveness isn't an issue.

Honestly, I don't like sedums very much. I grew up surrounded by them. I take it that mint is too deeply rooted? What about alehoof? (aka ground ivy, creeping charlie and about 15 other names).. Glechoma hederacea. Pennyroyal? (a mint, but not as big as most) Sweet woodruff?

I did plant H Palace Purple around some to keep feet cool ~ has worked very well & the beautiful foliage (plum & shades of) add interests & fills the lower greens of Clems quite lovely! Beautiful dark colored foliage Hardy Geranium might be nice too.
I have Spearmint planted in a bottomless, deep pot, sank in the ground (helps prevent roots from spreading) ~ I don't think I'll like Mint as an underplant - too scraggly for me.

Hope these helps ~ have fun w/ Clems!

Freki -

It looks like you are considering various goundcovers and spreading plants. I tend to plant things that won't spread or will only spread slowly near my clematis so I won't have problems with the roots of the clematis getting overrun. I have planted some moisture tolerant penstemons, heuchera, perenial geranium, hosta, and some low growing shrubs like Deutzia 'Chardonnay Pearls" or small spirea a couple of feet from my clematis and not had problems with the clematis getting overrun. I've also planted them near roses.

I'm looking at groundcovers because the plot is out of sight, and completely surrounded, a retaining wall on one side, shed on the other. The clematis bed is on top of the retaining wall. Other than my deep and abiding hate for hostas ;-), there is no point in ornamentals in that area. I'm looking at keeping the weeds down, the clematis roots cool and moist, and getting a "return" on the bed. If I keep the area around the clematis stem clear (pebbles? mulch?) of (shallow rooted) ground cover, would that work? and how much clearance?

I don't deliberately underplant any of my Clematis because I don't want to trample anything when I get in there to prune them. I also don't want any new shoots emerging from the buried crowns to be blocked. I want as many vines coming up as possible.

I also know from my own garden that they strongly dislike root competition as well.

Just mulch them and keep them well watered.

You do not need to shade their roots/crowns, that is a myth.

I do have multiple perennials a foot or two away with no problems, daylilies, huecheras, hostas, but nothing remotely resembling a ground cover.

All you can do it try it if you want to but don't think you must shade their roots....

My concern is root competition and that having to pull out a spreading ground cover might disturb the clematis's roots. Many ground covers have pretty aggressive roots which won't make the clematis happy.

Like Buyorsell, I mulch well to keep down weeds and plant more than a foot away from the clematis. One ground cover I grow that plays well with clematis is cranberry. I plant the clematis, put down a layer of corrugated cardboard, mulch the entire bed well with several inches of shredded wood and then plant the cranberry through the mulch by pulling aside the mulch, cutting an x in the cardboard, planting the cranberry and then tucking the mulch in around it. The trailing stems of the cranberry will root shallowly but can be moved aside before they root so they aren't near the clematis. They aren't weedblocking, but renewing the mulch every few years will take care of that. Cranberry has little shiny dark evergreen leaves, tiny pink flowers and large fruit (relative to the size of the leaves and flowers) that can accompany your holiday feast. The fruit starts out pale green and slowly colors up over the summer and through the fall, and is still a decorative deep red in the spring. The only catch is that it isn't tolerant of alkaline soils; not sure where you are so don't know if this will be an issue. I have it underplanted in most of my gardens and it winds happily through just about everything.

Veronica 'Georgia Blue' or 'Waterperry Blue' might work if you keep on top of it so that it doesn't get close to the clematis as it doesn't root deeply in my garden. I have no experience with other groundcovers that I would want to plant with my clems.

Was Periwinkle suggested yet? I love the shiny lush green carpet I have in some beds under some shrubs. Just make sure to keep a tight patrol & a few hair-cut sessions!

re periwinkle: The area will not be accessible of haircuts, and around here it forms very deep mats that strangle anything that doesn't qualify as a tree.

Can I use garden fabric in the immediate root zone? mulch.. how deep? I'll go with something shallow rooted like alehoof and rip it out if the clematis suffers, and try to keep it away from the root zone.

I have salvia May Night planted near my clems and believe it or not, I also have forget-me-nots planted all around them! The myosotis (FMNs) spreads by reseeding but is easily clipped down when done blooming and will still come back next year. I also have dianthus sweet williams around them.

I wouldn't use garden fabric anywhere in my garden as it's a mess once things start to root into the fabric, either my plants' roots from below or weed roots from above. (If you do a search for fabric on the perennials forum, you will get many threads on this.) My mulch is usually 1-3 inches, but is less than half an inch right next to the stem so it isn't sitting in wet mulch.

Thanks, I'm not a big fan of fabrics either. What about pea gravel as mulch? Has anyone tried that? At least it will stay dry.

I don't use fabrics at all. Much better to just use a natural mulch that will feed the soil over time. Don't rake out the old mulch! Just cover with new in spring. I use a pine mulch (not mini-nuggets and certainly not big nuggets, but a finer pine mulch) where the pieces are a quarter-sized and smaller down to dime sized. I just let it rot in place. :)

I also use a natural wood mulch. Gravel mulch doesn't feed the soil and is difficult to separate from soil if you need to weed or replant. I'm afraid that I am unclear about the staying dry comment, since clematis like moist, well-drained soil. My wood mulch has a dry surface but is moist further down.

I mulch with compost. We spread it once or twice a year.

how deep a mulch is usable?

I'm worried that a deep mulch will hold moisture on the stems and promote disease, the soil will remain moist enough on it's own. Very rarely are we dry enough to need to water established plants.

Normally I do not mulch plants, except for winter protection. I mulch bare soil only, medium cedar chips. So I really have little experience with directly mulching the critters.

I use three-four inches of compost. I don't worry about Clematis stems being buried since I plant the crowns three to four inches deep in the first place.

Thanks much!

I have this question also. I have daylilies that I wanted to 'shade' the Clems with. Only they spread quite a bit. I saw a brief mention of daylilies as underplantings, opinions? Does this work well?

You don't need to "shade" Clematis.

I have daylilies two feet from Clematis but not closer. Clematis do not play well with others in their root zones sucking up all the water.

I agree with BorS about Daylilies. Besides, planting Daylilies closer will make maintenance (division) difficult - Daylilies roots are huge and fleshy, you would risk damaging Clematis roots.

I wonder how many times it was repeated here that Clematis do not need their feet "shaded" or "cool" :o)

Well not so much for shade as for color combo, but i got it. Lol :D

I know someone already mentioned other perennials, but what about a dwarf Salvia? I'm thinking of moving my dwarf salvias over by my clems because they're being boxed out by the larger salvias... Or Thyme? I have a bunch of thyme on the edge of my perennial beds because I wanted something "steppable" or more appropriately I didn't care if someone stepped on it... but holds the birm well.

I have both underplanted and naked clems. The reason I like underplanting is because it can hide the lower leaf browning/drop that some clems tend towards. My faves are Heucheras as they have very shallow roots and are so easy to grow...Palace Purple is the reliably largest one and thus offers the most cover for those ugly lower clem stems. And they don't take offense when stepped on. I also have Astilbe and Peonies as underplantings. As well as Coneflowers...long taproot and two-three feet from the clems. If you plant far enough away you can use shrubs as both cover and as a climbing support. I have Red Prince Wiegela, roses, Purple Leaf Plum and even dogwoods.

I just discovered two dead Clematis that I had let weeds and forget me nots smother to death...:( I'm so annoyed. Spent the last two summers working on the front and side yards and ignored the back. Finally started clearing the bed where they were of forget me nots and weeds and discovered their stems rotted right off and no sign of a live crown in the ground...

It was two I don't see often for sale, Royalty and Helios. I'm so mad at myself. They weren't tiny babies either. Both planted more than three years ago from gallon pots.

I underplant with chrysanthemums. I like the way their foliage spreads and covers the clematis, yet the mums are planted a foot or so away. Mums a very shallow rooted, so they don't interfere with the clematis. If the mums get too large, it's easy to pull out a handful and plant them elsewhere.