OK thanks for the info. I'll cut back on the fertilizer. Maybe next year more vertical growth will happen! Any issues with adding the soil acidifer per Espomas directions? I live in the New England region of the US so we naturally have acidic soil. Just trying to get a really nice shade of blue in the flowers.

If your soil is already acidic - which it should be in your location - then you can also skip the acidifier. If anything, you might want to topdress the area surrounding the hydrangea (dripline) with aluminum sulphate, aka "hydrangea bluing", this fall or very early next spring. It is the amount and availability of the aluminum in the soil that increases or intensifies the blue color.

I would not try to acidify soil that is already acidic either. The only advantage is when the soil is slightly acidic (which produces a light shade of blue) and you amend the soil to make the blooms more blue. Amending the soil requires doing this forever as the soil will revert back to its original level if you stop amending.

Be advised that currently, the shade of blue in your blooms is due to the minerals in the potting mix. In the future, that may change all on its own. As the roots extend beyond and into your garden soil, the next set of blooms will reflect what minerals it then gets from your garden soil... then the blooms' shade of blue color will become slightly(?) different. This color change will stabilize after a few years (once the roots grow larger and get most minerals from your garden soil). It is at that time when you might want to amend the soil... provided that you do not like the shade of blue that the shrub is then producing.

You make a very valid point... Never thought of that. Thank you for this advice.

GG. Noob here with baby hydras nurturing them to full size. For usenortheasteners that see cold weather, would you concur that at least cutting the bloom to let the stem bounce back vertical before winter so it can get hard and woody before winter ? instead of getting woody at horizontal scale ?

My ES look just like that. While I'm enjoying the blooms for now, I am planning to deadhead them to help it get vert before it goes hard

Yes, by all means go ahead and deadhead whenever. Removing the older flowerheads should help things to become somewhat more vertical. And if that doesn't seem like enough of an assist, I might go ahead and loosely stake it as well. It wil be a lot easier to winter protect if the stem are growing more vertical than not ;-))

Might want to take a read through this before you deadhead. It does say after August you want to cut it between the bloom and the first set of leaves so you don't destroy next years blooms.

https://plantaddicts.com/pruning-hydrangeas/

You can take macs back to the next set of leaves (always in pairs on either side of the stem) at any time of year without worry. In fact, it is recommended to cut back to right above a leaf node so as not leave any stubs. Any latent flower buds are formed and located well below this point.

Is there anything wrong with not deadheading? I was planning on leaving my Nantucket Blue completely alone the first couple years.

If you don’t deadhead or stake, the branches will harden and become woody in their current shape, which I assume you don’t want. In general, it doesn’t matter if you deadhead or not, though doing so in the spring for any old bloom parts will make the plant look tidier, but in this case, it will help the plant develop a better form than it currently has. Deadheading isn’t the same as pruning, and while it isn’t recommended to prune plants for the first couple of years, deadheading doesn’t remove leaves, just old flowers, which in your case will be a good thing to improve plant shape.

One other note. You don’t mention where you are in New England, but location will make a huge difference with the amount of bloom you get without winter protection. If you are on Cape Cod or south along the coast you can get blooms most years without winter protection, but inland or north of the Cape usually requires winter protection if you want reliable spring bloom on a macrophylla like Nantucket Blue.

if you want your location to post automatically by your name as most of us have done, go to your My Houzz in the upper right corner, choose edit profile and settings. Choose advanced settings on the left and scroll down to climate zone for Garden forums where you can add your zone and also the state or region if you want. Then go up top and click save edits. This will help others help you better, and you won’t have to add it every post.

I'm in 6a. The Nantucket Blue tag says it's hardy to 4 (-20 to -30). It should be fine without protection but I was going to protect it anyways to minimize freeze damage.

The plant is perfectly hardy, but the flower buds may well not be. I get blooms maybe 1 year in 5 on unprotected macrophyllas and have been growing them just north of Concord NH for yonks. There are many threads on this forum from various folks bemoaning lack of blooms due to winter die back or late freezes after the plants have started getting ready to bloom in the spring.

For me I don't have a problem protecting. I only have two macro's. If I had 10..... That's a different story =)