Bloom times are going to depend a lot on your growing zone compared to the zone that the information posted is gathered in. In your zone, I would definitely believe that your clematis would bloom much earlier than what is posted. I wouldn't ever begin to mistrust that I have the correct clematis based on its bloom time compared to a published bloom time.

Frankly, this is an issue I've thought about before, also :-) Not that ID was in question because of differing bloom times, but rather why so many posters in other areas are reporting blooms on various clems while the majority of mine are still very firmly in bud.

I live in a very firm zone 8 (close to shoreline) and in various areas have a zone 9 microclimate with regards to winter hardiness. However, my weather is always slow to warm up in spring and never gets very hot in summer. Montanas and the atragenes are in full bloom in my area now, but very few of the LFH's are. In fact, the only one in my garden showing any blooms (and she just started) is Nelly Moser. Quite a few others are budded but no signs of color, yet. And I don't expect to see any signs of flowers from any of the viticellas until mid to late June.

I guess this is a long way of saying the same thing that Miguel did :-) Climate plays a big factor in bloom time. Since my climate is very similar to that of most of the UK, including the cool summers, and that is where the majority of the published info on clematis originates, the bloom seasons on my clematis mirror those in published sources. I'm just a bit jealous of those in warmer spring/summer climates that already have wonderfully blooming vines in their gardens!

Of course, you throw micro climates into the mix and it really is confusing. My garden blooms at least two weeks earlier than a friends who lives in the same zone and only 20 miles from me. Some of my clem's have been blooming for at least two weeks. I live in zone 7b and I had a clematis bloom in December this year. Go figure. I take everything that they say about bloom time and ultimate size with a grain of salt since it varies so much in different areas. I use the information as a general guideline but know it may vary somewhat.

Carol

"I'm just a bit jealous of those in warmer spring/summer climates that already have wonderfully blooming vines in their gardens!"

The grass is always greener Gardengal! I will pay for my early blooms by having them be out of bloom cycle when others will have clematis just coming into bloom. I will also be dragging hoses around earlier and more frequently than those in areas with cooler springs.

If I could snap my fingers and have my way, I would garden in a zone where the temps. never got higher than 72-75 and have rain twice a week! LOL I would willingly trade my earlier blooms for that type of gardening environment!!

I'm a couple hundred miles south of Gardengal but still in the grey and cool Pacific Northwest and my Type II Large Flowered Hybrids are all in full bloom. They don't wait until June.

Gardengal, I have to tell you this - although I have no blooms yet, I do have flower buds on Ernest Markham and Hagley Hybrid already. The buds are getting fat and are probably only a week or two from blooming. Have no idea why so early on these. It has been a cool spring. High today was in the low 50s, nearly 20 degrees below our normal for this date.

Both of these bloom fairly early each year for me, but this is sort of ridiculous. Ernest is on a west facing brick wall, but HH is in the open on the south fence (fake iron type).

Even tho I don't have any open flowers yet, except some extremely tiny Wada's Primrose, my older ones have a lot more fat buds than usual for this early in May.

Marie in ME

I have a lot of Internet friends who live on the East Coast or in the Midwest and they get Waterlily blooms months before I do. Even though their winters are much colder and they have much more snow. They have much more sun in spring.

The Pacific Northwest isn't terribly cold but it is very grey and overcast in spring.