I prefer that new plants spend their first year or two with me just developing a good root system. If they wish to bloom, well, I definitely will not complain.

I am obviously not in your zone 5, but I would wait one or two weeks after my avge date of last frost before planting anything outside. I just do not like having ole man winter zap the new tender leaves (the plant produces new leaves of course, but still....).

I'd be interested to know what type of hydrangeas you ordered before I'd comment on their likelihood to bloom this season for you - generally very young plants will not bloom their first year and even more likely the case with most macrophyllas.

If you acclimatize the plants correctly to harden them off, you shouldn't need to wait until last frost date - last frost date in my area is not until later next month, but my hydrangeas are leafing out nicely. They'll tolerate some cold weather. Put them outside during the daytime and bring into a protected area if temps drop a lot at night. If you do this for a couple of weeks, gradually increasing the time exposed to the elements, they should be good to go in the ground early next month.

Blue Moon Hydrangeas, and yes they are macrophyllas.

I was thinking I'd harden them off, but I just needed some recommendations from more expert gardeners. I'll start this process this weekend.

flshimmer, did you purchase these from Michigan Bulb? 'Blue Moon' is not a registered cultivar name and the only place it turns up is in the MB catalog. If so, the plant in question is Hydrangea macrophylla 'Nikko Blue' and its hardiness in zone 5 will be questionable. I would offer it winter protection as I would any other mac in your climate. True 'Nikko Blue's often display a remontant tendency or the ability to bloom on new growth as well as old but it's not a sure thing. Reliable summer blooming will require some effort with winter protection.

And with regards to Michigan Bulb, you should be aware they have a horrible reputation in the mail order industry, both with plant quality and customer service. And the mislabeling of plants or the spontaneous and illogical renaming of plants that are really something else entirely, as in this case. You might want to reconsider doing business with them in the future.

I did, and after I've posted a few things to this forum, I've learned a lot about MB. I'll prob not make a purchase from them from now on.

I've stuck them in the greenhouse and I'll prob move them outside when the weather is a little warmer. If I end up losing them, at least I didn't spend $50 for each plant.