While you can keep them trimmed back their first year in the ground, it is by no means a requirement. Rather, you will encourage better root system development by planting deeply to begin with and then cutting back hard at the beginning of the growing season (late winter/early spring) for at least the first couple of years.

FWIW, I've grown a wide assortment of clematis over the years and have never cut mine back during the initial growing season although I do routinely plant them deep and cut back hard the first two springs.

Personally I would just let these grow on this year and cut back hard again this time next year. And I would also mulch the base well to keep the root zone moist (or plant with some low growing perennial that will shade the area). And supply some sort of support as well.

Would you please clarify the planting deep. I planted 3 last spring and, according to the instructions, I planted them about 4 inches deep, but filled the hole only about half full. The instructions were to fill the hole as the plant grew. Unfortunately. I didn't get that done.Now I have green buds coming about 2 inches below soil level. Can I correct this by continuing to add soil as the plant grows or have I messed up real good ? Will adding soil cause the roots and stem to rot ? Help !!! Thanks

Thank you for your reply gardengal48. waynez5_ia, I searched for the answer as I was also curious specifically how deep clems should be planted. Here's a video from BBC Gardeners' World (UK). He recommends to plant them quite deep (see around at 1:40 through 2:50-ish). In my particular case, my clems were very tiny tiny young plants unlike the one in the video, as said in the OP, and if I had planted as instructed almost the entire plants had been under the ground... I would add soil as needed.

Typically, the recommendation is to plant them 4-6 inches deeper than they are in the nursery container. However, I have never planted a clem that small directly into the garden - I prefer to grow them on for a season until their roots fill a standard 1G nursery pot (most of my clems have been full 1G plants anyway). But I'd follow a very similar practice regardless of the size of the plant - there is really no need to wait to do it gradually and frankly, gardening gets so busy later on I'd likely forget anyway :-))

This is a practice that is routinely followed by scores and scores of clematis growers and if it were harmful to the plants by way of causing stem or root rots, it would be soundly denounced.

I do plant 4" pots directly into the garden since I am more likely to kill plants in a pot through inattention. I plant them the recommended 4" deeper than the pot surface and they do just fine. The one exception is when I am planting C. alpina, which to my understanding has slightly different roots that don't prefer the deep planting.

Thank you, gardengal48 and NHBabs.

I guess what is confusing about various
recommendations/instructions out there is that by the time clems have
grown 1G plants in a pot (where their root growth is by design "contained"),
they are probably no longer "first-year clems" and the "first-year
special pruning to promote new plants' root growth" instruction may not apply when
they are finally planted into the garden...

I think what I'm
going to do with mine is to prune to keep them to 16-24 inches high
this season anyway (I think I'll wait till they reach 10-16 inches), and then replant them much deeper this fall or early next
spring. Per some threads about transplanting clems in the clem forum here
(though it's not "trans-" in my case... just dig deeper at the same
spots) it sounds like it is doable even to well established ones, so
I'm assuming my one year old clems hopefully will respond well...

Do you think this is a good idea, and if so, which would be preferable, replant this fall or next spring?

I would either replant deeper now or else not replant. I wouldn't do it once they have established in that spot since there will be a larger root ball to dig up and more likelihood of damage as well as the plant needing to get re-established at a larger size. If you do it now, the plant probably won't even notice since it hasn't had time to grow out that many new roots.

Agreed. Do it now or not at all. There is no reason to prune to keep them 16-24" high either. If they are dying all the way back to the ground, which it looks like they did, pruning is done for you by Nature.

I also wouldn't prune all season to keep them at 16"-24". I've had the roots grow just fine pruning only in spring for quite a number of small new clematis (as long as I cage out the voracious voles!) Both BorS888 and GG48 have considerable experience growing (and in GG48's case selling and designing with) clematis.

Thank you NHBabs and buyorsell888. I bit the bullet and did it this weekend. I thought about your two options, and considering their growth long term I thought doing it right at this point would be a better idea.

As said in the OP my clems started very tiny early last fall, and they have been in the ground there for only 6 or 7 months through fall and winter. But they have developed surprisingly good root systems. So doing it now rather than waiting till fall was certainly a great advice, thank you! We tried to make as big a root ball as possible, but I'm sure we ended up breaking some roots...

They looked fine this morning. Well, they may be a little surprised and I gotta keep watching. Hopefully they will settle well soon... (fingers crossed).

Again, thank you for your help!

They'll probably be fine. Toss them a handful of alfalfa pellets. Cheap at feed store, big bag under twenty bucks. There is a hormone that helps clems send up new stems from the crown.You can buy alfalfa meal at a garden center but it is a lot more money. Rabbit pellets are out as they contain salt.

Thank you buyorsell888!! That's greatly helpful. I'll go and get a bag of alfalfa pellets. Thanks a lot!