You could trim them back but if the days are above freezing you can always set them outside during the day and then move them back in at night.

Were they potted up to be grown out size wise or to just keep them until you could plant them? If the plants are decent enough sized ones, they could be planted in the ground now. If you still have cold weather, the tops may get frozen back, but if heavily mulched the roots could start getting acclimated in the soil. I have planted clematis as early as the first of February here in NC. As long as the ground is not frozen, most containerized plants can be planted at any time of the year, although there are some times better than others.

I would plant it out, am sure your soil is workable by now, pile up some mulch on it until temps get higher. It does not hurt clem roots.

Well these are clems in pots for my deck- just std 12" pots...

If the pots are that size, then you should be able to move them in and out as the weather permits. Evidently your garage was not as cold as you thought or they wouldn't have started growing. Either that or place them under fluorescent lights and let them come up. I would still be pinching them back though to keep them in bounds and promote multiple stems from the crown.

Not sure which clematis you have in those pots, but most nonbushing clematis will more than likely quickly outgrow 12 inch pots. I assume you mean they are 12 inches tall or 12 inches wide or both perhaps??

NCK,

Do I pinch em back , all the way to the crown (last years node) or just break in the new shoots?

Yes its 2 small pots... like 1ftx1ft.I have will goodwin and henryii .

I thought Will G. will be a blue clem but mine aint blue!

Will G. is about a close to blue as they get. No true blue Clemmies.

I usually treat type IIs as IIIs the first few years in the ground so I would be pinching them back to within a few inches of the ground or right above a leaf node above ground level. Sounds like your clematis will likely outgrow those pots within this growing season. You may want to be checking the bottom drainage holes starting this summer to see if they need to be upsized as far pots go. I would shoot for a pot that is at least 18inches tall by 18 inches wide minimum if you want the clematis to live in pots all of their lives.

NCK,
You mean check drainage holes for roots ??

Also tell me :If I leave 'em outside in the deck over winter they will die right?

Yes, this summer as the clematis begin to grow, roots in the drain holes in the bottom of the pots means it is time to upsize the pot size.

I have many clematis that I have planted in pots, although much larger than the ones you are using, and they survive outside just fine. I am in zone 7a while you are in zone 6a but I would bet they would survive if they had large enough pots with enough soil mass.