I wouldn't rule out all the branches being dead yet. Not for another month or so. You can trim non-leaf producers after Memorial Day.

Nothing I know of will get quite as large as Nikko, which is a disadvantage in a large garden. In some places, Nikkos have spread up to 12x12'. Penny Mac could probably reach 6'.

Behind that you have Dooley, Endless Summer / Bloomstruck, David Ramsey, Blue Heaven, [a few other lesser known remontants] and maybe some other old fashioned ones like Brestenburg (mine blooms from the crown but hasn't been able to get larger than 2' in 3 years). None of these would likely get larger than 4'.

Others you can try at your own risk include things like Big Daddy, where there have been mixed results with hardiness.

That's still about it for now. Most newer products haven't undergone decades of testing, and are bred for smaller gardens.

I think that the biggest difference you will find will be if you plant a reblooming hydrangea. I am at the northern edge of the Hydrangea macrophylla range, and so usually the plant dies back to the ground, losing the spring blooms. I like having remontant H. macropyllas since even when they die back to the ground, I still get blossoms for the rest of the summer when the plants resprout from the roots. I have the original Endless Summer, and although I have read comments by folks from warmer zones weren't totally happy with it, I am thrilled with it and the other really hardy remontant H. macrophylla that I have, All Summer Beauty, which is mainly white.

Have you checked out Nantucket Blue? It is supposed to be a rebloomer version of Nikko Blue so if it were on your garden now, the new growth would produce bloomage (albeit later, maybe around July).

Caveat: somewhat new but I have not seen anyone complain about it so far. It is not sold in large qtys everywhere so you may need to order by mail. ivysmom has one in Houston. You could GW Mail and ask how it is performing for her over there.

You could do a forum search for "nantucket blue" and see who else has it. I do not recall anyone located up north like you though. You could also post a question asking if anyone is growing it and how is it performing.

Info:
http://www.naturehills.com/hydrangea-nantucket-bluetm

Nantucket Blue has been picked up by Garden Debut plants.

Use the link below to find retailers in your area (site is down as of this posting - apologies).

I've seen 3-gallons in my area for $34.95. Considering replacing a Penny Mac with this plant to test it out.

Here is a link that might be useful: Garden Debut - Find a retailer

How much sun can the Nantucket Blue handle? Every thing I read says "partial shade".

If you're anywhere in zone 6 or below, or north of about the Mason-Dixon line (MD border) you can probably go with partial shade. South of that you'd probably want mostly shade after noon, or "part-sun". Same goes for most macs, except the whites whose blooms can scorch the easiest, so they need the most shade.

Reviving a very old thread..... Apologies if i'm breaking a rule. I actually picked up a Nantucket Blue this past May. Knew nothing about the plant other than it looked the healthiest out of all the big leafs at my local nursery. Come to find out after I bought it, its a highly sought after variety in my location due to my cold winters and it's supposed zone 4 hardiness.

My Info:

1) Planted in zone 6a (Massachusetts)

2) Planted in a location that only gets mid day sun (roughly 3-4 hours worth of direct sun). Location was my only option for direct sunlight as close as I could get it to morning hours. Rest of garden is shade based or late afternoon direct sun based.

Impressions so far:

1) Bloomed like crazy from the day I bought it in May all the way up to end of August. Very impressed with it's blooming characteristics in its first season. Blooms were HUGE.

2) Most of the growth was horizontal in the first season. I didn't get a lot of vertical growth this year. I did have a couple stems go vertical but the weight of the blooms bent them down to a horizontal position. My understanding is this is expected with a new plant. As the root system becomes more established, it will have more vertical sturdier growth in the years to come.

3) It's a thirsty plant like any other newly planted macro. In July I had to water it twice a day to keep it happy. Huge drink in the morning and then again when I came home.

4) Color is a light blue. I wouldn't consider it a dark blue. My soil pH hovers around 6. I could probably make it a darker blue but would require regular soil acidifer applications.

Unknown:

1) Since this is my first season with it, I'm not sure how well it's going to survive a 6a Massachusetts winter. It does say it's cold hardy to zone 4 so it should be fine. Debating on if I should winter protect it......

On reblooming/remontant hydrangeas in MA, I would not look for flowers from the current season's growth until late summer....August or September. In northerly locations, bigleaf hydrangeas do not even bloom from old/last season's growth until typically July!!

Saying a macrophylla hydrangea is hardy to zone 4 isn’t saying much since many will, in fact, survive up here. Question is will they ever bloom.

Also, to say they are only ‘root hardy’ up here is not completely true either. Of course there will be variation amongst the cultivars and the winter but the ones appropriately marketed as zone 4 have most years have some stem survival and bloom in July with more flowers in August and September.

Billy—how is the Nantucket Blue faring? I live in zone 6a in MA and am on the hunt for the right macrophylla hydrangea! Thank you!