Most are hardy in the ground to zone 4. Do you know what Clematis they are?

The absolute hardiness ratings for most clematis is not known. If you look at most clematis hardiness ratings, you will see most listed as hardy in zones 4 to 9. No real empirical data exists for the hardiness ratings and we all know that zonal information means nothing since it only lists the maximum and minimum temperatures expected in any zone. Winters in any given zone will vary tremendously especially with regard to amount of snowcover, humidity levels, swings in temperature, etc. Also zone ratings do not take into account microclimates that can exist in one garden and not exist in another of the same zone rating. Experience with the clematis in your parents' garden will reveal whether they will be hardy or not. Participation in the COTW survey on clematis hardiness will help aid in finding out the real hardiness ratings for clematis.

I do advise however that the clematis be mulched well since mulch can ameliorate the vacillations in soil temperature in any zone. Sorry I can't give any more specific information, but no one can really say whether the clematis you chose will survive or not. Again, experience over time in your parents' garden will be the ultimate source for your question. Good luck!

The clematis should be fine. They survive here in Northwestern Ontario. My suggestion would be to ensure to plant them deep so they develop a strong root system. To be extra sure they survive, shovel extra snow on top to insulate them. More is better.

Danni

We still don't know the type of clematis that were planted. If they were montanas, then they might survive and not ever bloom since they will die to the ground each spring or have the flower buds frozen off each year. My point is that the absolute hardiness ratings for most clematis are not known due to no one ever gathering that information and no one testing them as such prior to introducing them into the trade. Also, zonal information does not mean anything about whether a plant will survive in any zone--it only gives you an idea of the average low and high temps in each zone. Two people in the same zone can have extremely different growing conditions. I have posted this below and am doing so again to drive home the idea that growing zones tell you NADA about whether a plant will survive in your growing conditions or not irrespective of your zone!

From Ellen Hornig's Senenca Hills Perennial website:

Plant hardiness
We can repeat this rant until we're blue in the face: hardiness zones do not tell you most of what you need to know to grow many plants. For example, Syracuse, New York and Omaha, Nebraska, are both in zone 5. Do you really think their growing conditions are similar? Of course not. The totality of the growing climate, not just the winter low temperature, affects the plant's performance. Snow cover, soil type, presence of pathogens and predators, patterns of temperature change, patterns and amounts of rainfall, drainage, and other things all matter. Is there any simple way to summarize growing conditions? No. A good gardener experiments. A good gardener kills a lot of plants. A good gardener is not literal-minded about hardiness zones, either way.

To complicate matters, when you attempt to grow plants from ecosystems very different from your own (some of our South Africans, for example), it may be impossible to predict whether they will do well for you, because too little is known about their cultural requirements. Oswego does not much resemble the Drakensberg, but a lot of Drakensberg natives seem to like Oswego. Why? We aren't sure. Maybe we just have a magical mix of conditions. Doubtless you too have a magical mix of conditions, but perhaps it suits a different set of plants. You must be willing to experiment, because we simply cannot tell you whether any given plant will do well for you.

The bottom line here is that we include hardiness zones largely to pander to popular prejudice and give you a small degree of guidance. The fact that your zone number is equal to or lower than the one given for a particular plant must not be construed as an assurance that this plant will grow for you.

Tell your parents to prune the clems in March or early in April, when the leaf nodes/buds start swelling. A lot of English clematis advice suggests Fall pruning, which does not work for the Midwest.

Why doesn't fall pruning work in the Midwest? I hear that all the time but never heard what is suppose to happen to the plant when they are cut in fall. I should tell my plants that this fall ;-)

I have cut everything down to the ground in fall or left a foot of vine. I've also cut them at 3-4 above the ground. Then do the final pruning in spring as soon as the ground thaws. No one has died yet.

I know that one is Multi-blue, one is Kilian Donahue, and the third I think is, um, the popular one that is pink with a fuschia bar down the middle (Nelly something?). I told them to keep the tags, but somehow they got lost. My dad has access to lots and lots of leaves in the fall. Should I tell him to pile them high on top of them? Also, the vines should remain throughout the winter, albeit brown and brittle? Oh, and when we bought them, I made sure that all the tags said hearty to zone 4 (rather than z5).

Thank you all for your advice.

Fall pruning could stimulate new growth which would not be as winter hardy as growth that has hardened off.

Fall pruning might stimulate growth in the warmer zones but in those zones Janet and the OPs parent's are in, late fall is probably more than cold enough to put the clematis into dormancy so that pruning then shouldn't stimulate growth. In my zone 7a garden, I prune in late December and don't have any problems doing so. Remember Winter starts around Dec 21st so if I can get away with pruning in zone 7a in late December, people further north can get away with it even sooner.

Here in the wacky Midwest, Fall pruning might stimulate new growth b4 the onset of Winter. In 5 of the last 10 years, we've had temps in the 50s & 60s for several days at a time, well into November. We can go from temps in the 60s to highs in the 20s within 48 hours (or less). And a gardener can never know which year will be the 1 with the very warm extended Fall. To be safe, at least here in Northern IL, it is better to wait until late Winter. Besides, the plants are still green in Fall, & near Winter's end, I can tell what is dead & what is not. With Type IIs, if I pruned in Fall, I'd have to prune again b4 growth begins in early Spring. I'd rather do the pruning once. I suppose it may not matter with type IIIs.

Interesting Entling. I would have thought you in that zone would not have to worry about things regrowing in December. Curious that I can get away with it here in NC and you can't in IL. I have found that once the clematis in my garden get hit with a cold spell, a minor warm up causes no issues with any of them thinking about resprouting or growing new foliage. In fact, I am more concerned with stimulating growth by pruning too early in the spring. I believe that day length may also play a factor in whether pruning will cause regrowth as well as temperature. I also like pruning then since I am usually overwhelmed with gardening chores in late winter/early spring. Guess we all have to find out what works best in our own gardens and growing zones!

I'm thinking mostly of 1998, the really weird Fall. People around here had roses blooming in December. Of course, most of those roses died because they could not harden off & go dormant b4 the freeze came. One writer has described the Midwest as the "Zombie Zones." The point is, around here, better safe than sorry because the only thing predictable about our weather is its unpredictability.

They say the same thing about our climate Entling. I guess any zone can have a freaky late fall/early winter season but I am going to continue with my pruning regime. I figure that most of mine are established enough that they should withstand any freeze back after a weird warm spell. If they can't, I view it as Nature's way of telling me which clematis to grow and which are left for other zones! LOL

I can't speak for all clematis, but I don't think, as a rule anyway, that they are as fussy as most roses.

My clematis don't suddenly put on new growth after being cut back during the growing season, in fact, it's the opposite. They sit there for a long time doing nothing, so I don't expect much, if any growth in late fall. At least I haven't seen any yet.

One thing I would caution your parents on is applying mulch. I had a jackmanni that came with the house and did beautifully every year. Last year I decided to heavily mulch (6" of shredded leaves) that plant along with all the other beds in my garden in October. I lost that clematis along with a couple of other hardy perenials.

The winter wasn't much different than the ones preceding it...The only thing I can think that may have happened is that I applied the mulch before the ground had frozen.