As far as the ones where the soil has settled..it wouldn't hurt to add more soil...Clematis love their roots to stay cool and with winter coming in your cold zone..they will appreciate the insulation..Plants in pots are far less insulated than in the ground...I would not add cowmanure until this coming Late Fall/Early Spring..you don't want to stimulate growth this late in the season...as far as the one that isn't showing any sign of life..I would leave it alone..it may just be focusing on producing roots and will emerge next Spring..Make sure and mulch ontop of them..keeping the mulch away from the vine...do you plan on bringing your pots into the garage for the winter?..Might be a good idea !!..Hope this helps....Jeanne

I agree with what Jeanne has said above. Don't mess with the one that hasn't put out any growth because it may be sending up a shoot that is just beneath the surface and digging will damage it. I would give it until next year to come up and then if it hasn't done anything by mid spring, I would be sorely tempted to dig away to find out if it has rotted away or what is going on.

Just remember that if you add composted manure of any type (don't use fresh manure ever or you will burn your plant), it is organic matter and will eventually be utilized by the plant as food matter and will hence "go away", leaving your plant no deeper than it was originally planted. I would add the soil now to get the plant to the appropriate depth and wait for next spring to topdress with any composted manure. I would remove the leaves on the stems to be buried so you aren't burying organic matter than can rot. Remember that you should plant clematis deeper than they were originally planted. Doing so buries dormant nodes that can come into play if the clematis is cut down by an animal or wind storm and also if the clematis should get clematis wilt (not that that should be a problem with either Polish Spirit or Sweet Autumn clematis).

Thank you so much for the info guys. What kind of soil do you recommend? I used soil from a garden that I had reduced down in the spring (good, loose soil) with manure that was pretty composted. For my other pots I usually use MiracleGro soil. I checked again today and they both need about 6". Maybe I'll add about 4" of soil so in the spring I can add a couple inches of some manure. I don't want to just go buy plain old potting soil, but maybe that's what I should do?
The two smaller potted clems will go in the garage or crawl space for the winter. I have to make sure I put a marker in them. This will be the first time I try to save something in a pot in the garage. How about if I put them inside a styrofoam cooler in the garage? I did have a mum make it through the winter in the garage last year (not that I had done that on purpose). These I believe are type 2s.
Oh, and I forgot. I do have two jouiana praecox that survived in pots last winter (one in a half-barrel). They bloomed really nice this summer.
Again, thanks for the info!

Here is a picture of the SAC. The pot is down below. From the top of the pot to the top of the lattice is about 10'. I'm so glad it's done so well. I'm hoping for a nice mild winter as I cannot move that huge pot.

Here is a link that might be useful: SAC

Generally speaking, you should not use garden soil as potting soil in pots. It is too heavy, tends to compact down over time, and the drainage is not as good as a potting mix you purchase. I typically use one of the standard potting mixes that I can purchase at a local nursery or local home improvement store or even Walmart.

I would suggest you not putting your small pots in a cooler to help insulate them. I am sure that they will survive the winter in their pots in your garage or crawl space just fine as is. Good luck and just a note that your SAC looks great.

Yeah, I know I shouldn't have used garden soil, but the pots are HUGE. It would take many many bags of potting soil to fill them. My garden soil was pretty good, have been adding leaves and grass for 15 years. I will only add potting soil to it now though.
I was wondering too, if I prune the SAC in June, will it get bushier down below? As you can see in the picture, the neighbor's dining room window is right there. I'd like some privacy there, that's why I planted it in a pot there. There is all concrete patio under the deck and out about 4' so I had to put it in a pot.

I can't answer your question about the Sweet Autumn Clematis since I don't have one but I just wanted to tell you that it looks great.

October, you can start trimming back your clematis the minute it starts growing in the spring to encourage branching and so you will get a bushier plant. I trim mine back off and on until about July or so and still have blooms on mine.

October - Just curious as to the dimensions of your pot, and if you have any pics of it. Yours is doing so well. I recently potted a SAC, and am hoping the pot was big enough. Thanks!

I did go out and take a couple of pictures but for some reason they won't upload into webshots. I'll try again later. The pots are at least 2 1/2 feet tall and about 2 1/2 feet across. I sure hope the SAC makes it through the winter. I splurged and spent $35 on it spring 2004 - wanted some quick cover for privacy. I had planted it in the gound last spring, it grew well and bloomed last fall. I transplanted it into the pot spring 2005. It's done well again. I planted it in the center of the pot and have an automatic drip system watering it daily. After I add the soil and after it dies back, I'm planning to cover the pot (mound it probably) with some chopped up leaves (with a collar around the stems). I'll then cover it with either some landscape fabric or some black plastic. Unless, that is, if someone tells me it's a bad idea?

All I do with small clems, put in gallon pots and bury pots for winter, I don't even mulch and they do fine and grow great in spring in SW Ontario.

Here's the picture of them in the pots. I think you can tell how big they are in this one. You can see the AC unit in the background.

Here is a link that might be useful: Huge Pots