Hi Kate! I can envision lots of lovely combinations with the plants you have available. When I'm putting a container together, I think about "spill-over plants" and the mature shape of the taller plants. I've never grown astilbe, so I'm not sure how well it would do in a container of the size you're describing, but from what I know of the shape of the plant it would be a beautiful focal point for the planter. Your heuchera would make a nice accent for the taller astilbe, with the varigated vinca planted all around for the spill-over effect. (I grow this plant in my garden and use it frequently for containers... periodic snipping back keeps it from getting too stringy.)

Just one combo idea... you've got lots of options with what you have available! ;-)

Kate, lose the ivy and the vinca major. The astilbe will be done flowering in another week or two, after that, the plant is of no special interest.
The planter is only 10" wide and even the heuchera gets wider than that so there's not enough width for astilbe to be a backdrop to the heuchera.
There are trailing varieties of coleus that would give color and texture and the spillover effect you want. I'm not sure an 'elephant ear' will fit the space but if you want it as a focal point, the coleus underneath would be a good color. Tiarella varieties have a nice leaf,similar to the heuchera.
Just remember that heuchera,astilbe and tiarella want a mulchy soil that holds moisture but drains well so standard bagged mixes need additional garden soil and some small bark fines or composted leaves.
If I had such a planter I'd fill it with glorious varieties of coleus and heuchera that love a north facing growing location.

Thank you both for the ideas. I forgot that I had some Solomon's seal, and then the blue-green color of the original planter didn't look good with it, so I switched to a round pot. I also discovered some vinca minor creeping into my yard from another neighbor, and since the variegated vinca major didn't go with the (variegated) Solomon's seal, I used the dark green smaller vinca. I also used the heuchera and stuck some of the red astilbe in. My astilbe hasn't bloomed yet, and it's quite small, but I like the leaves. If I can find the instructions on putting pictures in posts, I'll put it in to show you how it came out.

Now, I still have the rectangular planter, the elephant ears, etc. This is my first elephant ears plant, so I really don't know what to expect from it. I'll try something for the back yard.

k.

Here it is. Not exactly stunning, but it's my first attempt at putting a planter together.

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Kate, for your planter in the photo, I'd lose the vinca and replace it with Peacock Moss (Selaginella uncinata), as your Spiller. Peacock moss is amazing in shady planters in filling out at the soil level and trailing down. Great texture, and nice at catching light. It really helps a planter look lush.

I'd also take out the astilbe, perhaps put it in a smaller pot at the base of the bigger one, and substitute with a fern for some height in the middle. Autumn fern would be an evergreen choice. Or, put that darker Elephant ear in there; EEs are dramatic, great as an entryway focal point, though they probably would appreciate a larger pot than the one you have now.

Thanks, Phylla. The peacock moss looks interesting. So you think some height is needed? And maybe a few more pots? My elephant ears are in a 5-inch square pot and stand about 10 inches from the top of the soil. Maybe when I divide them they'll get a lot bigger.

k.

One consideration when growing in planters with perennials vs. annuals is when you are stuffing a planter with annuals you are not expecting them to live past the first season. If they get a little cramped and stressed, you are going to disposed of them at the end of the year anyway. Perennials, on the other hand, require a little more forethought regarding the care they need to bring them into the next season. Stressing them out this year is going to affect their future growth.

In my opinion, that is a pretty small pot for what you want to grow in it. As Dottie said earlier, that Heuchera is going to get bigger than that. I planted out Palace Purple Heuchera last spring that were not much bigger than that and by the end of the season they were about a foot and a half across. This year, I can't get my arms around some of them. I also agree with ditching the vinca. You want something that will spread nice but not completely take over a pot and choke out other plants which is what vinca will most likely do.

That being said, there is nothing wrong with a little experimentation. Different people enjoy different things and have different ways they care for plants which affects growth habits. Through trial and error, you will figure out what you like and what works for you. You just need to keep an eye on your project and be prepared to upgrade to a larger pot and remove or thin out plants as necessary.

The link below is to a decent article regarding the base components of container planting and gives a few suggestions.

Here is a link that might be useful: Container planting. Thrillers, Fillers, and Spillers

Thank you all for your good suggestions. Aezarien, I especially appreciate the very helpful article. I am hoping to get a large planter, but haven't found exactly what I want. I did get more soil, so I may move some out of this planter into the rectangular one and make some other changes.

Thanks again.

k.