I do not know about Greenwood Nursery, but you can read reviews here.
As for Wayside, I ordered several Clemmies from their last year sale. They send bareroot plants. It takes a lot of TLC to nurse them.
Bluestone Perennials sells Donahue's Clematis in small pots. Tiny, but vigorous plants with good root system.
Silver Star Vinery has it on sale now. My first experience with this company was a little dissapointing, but usually people are very happy with their plants.
It is a very common variety, I saw it at Home Depot and Lowe's many times.
Good luck!

Wayside is over priced for tiny starts. I'd buy from Silver Star Vinery instead. Although I would not mail order Jackmanni. I see it everywhere, cheap.

Thanks for the replies. This afternoon I decided to try one nursery that I forgot about and I found one, actually they had two, plus other varieties!!! I am so happy, though, I did pay $40 for it, but it is about 3 ft. tall. I had my DH husband plant it already. I just love it.

$40.00 for a Clematis? Ouch....
Congrats on your new Clematis.
If you would like more, try Brushwood Nursery. It ships you gorgeous Clematis. Some would bloom the same year. Many others will bloom the following season. I bought several last spring based on recommendations on this forum. They all are doing extremely well. Since I ordered them a little late, I could only find 'Huldine' at Garden Crossings. The plants arrived in very good shape too. I highly recommend these nurseries.
Have fun.

Here is a link that might be useful: Brushwood

Wow, and I thought I had overpaid a few years ago when a local expensive nursery charged $30 for a one gallon pot.

Oh, I agree that the price was high, but I paid $29.99 for my other two a few years ago. The nurseries in my area are high.
Hey, at least I got what I wanted and it's blooming.
I am going to try an post a picture of it in a new thread.

now i'm curious, where are you in NJ? I can think of many local sources for clematis at better prices.. But I'm on the border of morris & union county.. easy pickings for me..

OUCH!!!!! I saw Jackmanni today for $14.99 in a gallon pot. Doesn't matter how tall they are, when buying Clematis, you want multiple stems rather than height as ideally, you should prune when you plant. I've seen it for $9.99 at Home Depot, in a gallon pot.

kitova, I'm in Colonia. I shop at Parkers in Scotch Plains, Bartell's in Edison, Miele's in Clark. But this clematis I bought at Rising Up in Colonia. Believe me, I hated paying $40, but I got what I wanted.