Dunno :-) Do you plant them deeply and prune back hard the first couple of years? Both of those practices encourage better root system development and more stem development from the root crown. I also like to mulch with alflalfa, bunny poop or use an alfalfa meal fertilizer as alfalfa has a natural growth hormone that encourages basal shooting or the development of more stems from the root crown.

Some clematis varieties die to the ground in winter and new stems come from the plant in spring. Other varieties, like the ones you apparently have, retain last years stems and new growth comes from them. This is normal. Since the new growth is weak, the problem is probably related to where they are growing, the condition of the soil, how they are fed etc. You need to tell us about those factors.

Hmmmm.....other than the fully herbaceous, nonvining types of clematis, none of mine has ever died all the way back to the ground! And I have grown all types :-) That might be something that happens in colder climates but here, all vining clematis will develop a thick, woody trunk (or mutiple trunks) in time.

I’m by no means an expert but my beginning experience with clematis was much like yours. I had two (nelly moser and jackmanii) that were amazing from the start but all the rest were just....ehhh. For years.

And them I found this site and learned about how deeply they like to be planted and wow, night and day difference.

Now I get new shoots growing from the ground on all of them. So while I think water and fertilizer are important I 100% believe that if you dig them up and plant them deeper you will be pleased with the results.

Clematis like Jackmanii bloom on new wood so the old stems can be removed in early spring.

Not all the way to the ground :-) New wood blooming clems - pruning group 3 - can be pruned back to the 2nd or third set of leaf axils....or 12-18" from the ground.

And with Jackmanii, you also have the option of pruning like a type 2. Or not at all if that method floats your boat...although that does leave a rather messy tangle of old vines and elevates where the flowering starts on the vine.

Gardengal, I prune Jackmanii to the ground. The new stems emerge at ground level and the plant stays neat and tidy.

OP here.

I do remember the names like Nelly Moser and Jackmanii as two of the types of clematis that I have. None of mine become woody over time. They look like dry grass stalks, as well as having same texture, and pretty much look dead, until such time as the new spring growth pops up from one of the leaf nodes, leading me to realize there is still life in that particular basal stem. But it means I feel like I have to be extra careful because the weak and dead looking basal stem looks so weak, I could basically break it just by brushing up against it wrong.

As the growing season goes on, I don't really get more basal stem. I just get that new growth (from the leaf node) being the one that grows for the plant that year.

I planted mine about 3-4" deep as a bare root. Once it was growing up year after year, I did not re-do it (plant it deeper) since I always worry about disturbing it. I mulch around the area for giving it added moisture retention as well as breaking down and adding to the nutrients in the immediate area. I do not add other kinds of fertilizer very often, such as spraying or watering it with foliar feedings or root feeding fertilizer.

Do you ever cut them back? As said above, deep planting and pruning will help create fuller plants.

I didn't cut them back in the early years because each spring, I saw this kind of condition -- a weak , dry looking stem, and I thought the root would need whatever growth was there, coming out, to get stronger. However, that seems to be what I should have done anyway.

Pruning, even severe drastic pruning HELPS Clematis. I would cut them all back drastically and mulch with alfalfa pellets/meal. I buy a big bag of alfalfa pellet horse feed for ten bucks at the feed store rather than a little box of meal at the nursery.