Just give your Clematis "Jackmanii" some rose fertilizer or tomato fertilizer...the "P" is higher in the N-P-K ratio..clematis prefer an Alkaline soil..that is one with a ph higher than 7..did you hard prune your "Jackmanii"?..Mine is about 4 feet tall now..so with you being in a colder zone sounds about right...water it well...Jeanne

Yes, I did prune it all the way back to the ground. Is Alkaline and acid soil related? I have fertilizer for azaleas, would that work? If not, I can buy rose or tomato fertilizer.

I would buy Rose or Tomato Fertilizer...You mean you pruned it FLAT and even with the soil?..You don't prune that hard..you leave about 3 leaf axils..and those will swell with leaf buds and then start sending out vines..if you pruned it back to the ground then that is why it is so slow coming back...
No Alkaline and Acid soil have different phs ..Azaleas love acidic soil..don't use that fertilizer..your soil is probably ok or your clematis wouldn't have flourished last year and the years before..just top dressing your flowerbeds with an inch or so of composted cowmanure or compost is just fine...before you start messing with the ph balance of your soil..you'd need a soil test..which I doubt you need....Jeanne
Check my link..it has a pic of how they look after pruning..

Here is a link that might be useful: Hard Pruning for Group 3's

When is the correct time to prune it? I pruned mine just last month, and all I had was dead vines, so all I was really doing was pulling up dead wood. Am I doing something wrong here?

Donna..pruning time varies with each zone but you can calculate doing it the same time you either Prune your Roses for Spring..when the Forsythias are in bloom..late winter/early spring..that time for me is around Feb 14th..the vines you saw weren't dead...they just look it in winter time...but in saying that the pruning group 3/viticellas BLOOM on new vines grown that season..hence the reason for hard pruning...if you saw my link and pic on that link then you should have seen those "Pruned dead-looking sticks" has green leaf buds forming at the leaf axil...Jeanne

Your picture looked really good. The wood looked so smooth, if that is the right word to use. Are you saying my dead looking vines will look as nice as yours once the new bloom starts? What I pruned looked like a tangled mess of dry, dead sticks, nothing like in your picture. Also, what is this 3's and 2's that I'm reading about?

Yours looked like a tangled mess because yours is older than mine (and probably never had been pruned?)...clematis have different pruning groups..so when you say "pruning group 3"..you are referring to viticellas/those clematis that bloom on the new vines that are produced in a growing season...they must be hard pruned in order to grow new vines for blooms ...those that aren't hard pruned usually have just blooms at the top.
your Large Flowering Variety which bloom in spring and later on in late summer/fall are pruning group 2's they bloom on the old vines produced the season before..some of these can bloom on both new and old vines..they aren't pruned EXCEPT to keep in bounds/to shape and ONLY after they have finished their bloom cycle..
When hard pruning..I just grab each vine at ground level and count up to the 3rd leaf axil and prune above it..and continue on until all vines are done..then I yank the top/cut vines away...it really is very simple..it doesn't have to be the 3rd leaf axil..it can be 4th,5th etc where ever you want your clematis to start growing and blooming...Jeanne

I was doing a search on pruning, and it looks like my jackmanii is a group 2a, I think (?) So I need to wait until spring to see if any new shoots come up before I prune, so that I can tell the dead wood from the new growth? Not until last summer did I cut mine more than half-way back because I thought I would get another flush of flowers (nope, didn't work). All other times, I've waited until spring and just cut all the wood flush with the ground. This is confusing....I think I need someone to actually be there and guide me through this process. I hope I do learn someday LOL.

hi donna. i'm in the same zone as you.

i don't know how you reached the conclusion of your clematis being pruning group 2a. if you have a jackmanii, then it is definitely prune group 3. which means they bloom on new wood.. which means you did the correct thing by pruning it in spring! it should grow back vigorously over this summer and bloom for you around june/july.

the reason you cut back group 3s is because when you don't, what invariably happens is it blooms on current season's growth and thus you get bare leg syndrome - flowers all at the top where the new growth is and nothing at the bottom.

my jackmanii has new growth barely 4" long and i'm in the same zone as you. but spring for us here has been a bit slow in coming, so i am not worried. once consistent 60 degree weather hits, i'm sure the shoots will rocket up.

to summarize, for group 3: prune only in early spring to about 1 foot off the ground. don't be alarmed by dead-looking stems in winter - they are not dead. i prune my clematis in march, i assume it will be roughly the same in your zone.

hi kitove, Jeanne was telling me it was a prune group 3, and something about large flowering varieties that bloom in the spring and then later again in the late summer/fall being a group 2. I got confused, sorry. I'm not that experienced with a clematis, and I do have 2.

Last spring I planted The President Clematis. That one is coming up well. I can put a plant in the ground and it will grow, but knowing how to prune is another story. I will remember to prune 1 foot from the ground next spring.

hi donnas, ahhh i see. don't worry it is not as confusing as it at first seems, i'm sure you will be a pro next year!

as for your clematis "the president", it is prune group 2, so you need not prune that one at all.

if you get any more clematis and want to know the prune type, just look it up on the hull database, link below. it is a great resource and has pruning types and instructions too.

Here is a link that might be useful: hull clematis database

You should know that pruning 3's as 2's or 2's as 3's won't really hurt the plants. It just changes when and where they bloom.

Pruning all the way to the ground won't hurt them either as they sprout up from the roots. Several of mine did die all the way back, there was no life at all in the vines.

No worries. Clemmies are tough.

kitova, I'm looking at my little ID card that came with The President clematis. It says "In late Feb. or March, remove weak and dead wood and prune as follows. Prune lightly spacing stems so that next year's blooms can open well". Are you sure I'm not going to have trouble with this one too LOL.

Another thing I'm wondering about, is I have this clematis (The President) in full sun, not full sun to partial shade. It is in my front yard and is growing up against my house. This area really gets HOT in the afternoon in summer, as my house faces NW. I hope I don't have to relocate it. I guess I'll have to see how it does?

Prune it hard the first two years and then you don't have to prune it at all unless it has dead stems or gets really tangled. Or you can prune it hard every year for simplicity.

It should be fine in the full sun. Full sun to Partial Shade on the tag means either not both.

hi buyorsell888, I haven't pruned the president clematis at all. Right now, one stem is over a foot tall with some smaller ones maybe 4 inches tall. It was fairly small when I bought it last year, so I didn't bother with it. I wasn't really sure about the full sun to partial shade thing. It would get shade in the morning, but scorching heat in the early afternoon/evenings.

My jackmanii clematis has now grown taller than my mailbox in a little over a month! I really didn't expect it to get this big since I pruned it all the way back even with the ground earlier this year. Now if it just blooms all over I'll be happy. I've noticed though, that mine always bloom later than others in this area. Is that because of me pruning it back to far? Thanks.

Donna...yes, by your pruning it so severely It will make it bloom later than normal..Jeanne

Next year you might want to stagger the length of the stems you cut. This might give you earlier bloom on the taller stems first and later bloom on the more severely cut ones. This is just based on my reading, not experience yet.

Marie in ME

That's what I figured Jeanne, I think I really asked a stupid question here :) eden_in_me, I'll try staggering them next year. I do know I'll NEVER prune them all the way to the ground again.

I have gone out and gently wrapped it around my mailbox so that it spirals. I used one piece of twine to tie it to hold it in place. It was just growing straight up behind the box. I thought it would automatically climb around the mailbox post itself, but it didn't.

A mature Jackmanii is really too big for a mailbox unless your mailbox is on a 8' post.

You need wire fencing or bird netting on the post to get a Clem to climb.

No questions are stupid.

um....you are kidding me aren't you ;) I'm sitting here looking at my wall from the top all the way down to the floor. That's a TALL mailbox post...LOL. I guess I should move it. But I'd be afraid if I tried digging it up, even if I waited until this fall after it has finished blooming I would kill it. And knowing my luck, I would.

Kidding about mailbox being 8' but not kidding about a mature Jackmanii being too big for a mailbox.

Jackmanii generally matures to over 10' tall.

Clematis won't spiral around a support usually they grow straight up.

They need something to grab on to, they can't grip a post, it is too wide.

transplanting shouldn't be a problem but it might take another year or two to get too big and you might decide to move by then and not worry about it.

Is there a clematis suitable for a mailbox or do they all get 8-10 feet high? There is a lady who lives several blocks from me and she had her clematis spiraling her mailbox. It was full of large purple flowers. I don't know if it was a jackmanii or not... I didn't stop to ask her. I thought it was so pretty, that is where I got the idea of clematis/mailbox.

There are many that don't grow that tall..you can go to Cotw and Click on search and then you can even check by color/pruning type/bloom period and Mature Height...Jeanne

Here is a link that might be useful: CLEMATIS ON THE WEB SEARCH

Jackmanii is a common purple Clem but there are many more that are purple and shorter growing.

There are many people who plant big Clems on small supports and don't have problems the first few years but then when they hit their stride, watch out.

They will spiral around if they have a wire, string or net to cling too. I have an online friend who uses grapevine wreaths, cut apart to spiral around lamp posts for them to climb on.