They aren't exactly house plants, and you may have some trouble trying to grow them indoors where conditions are far from perfect.. for four entire months.

Any reason you don't want to just let them stay dormant until you can move them outdoors in the spring?

Also.. how cold is your basement?

I leave some of my cuttings in the cold basement until March and I am in zone 8b. PNW and most are very happy in the cold and dark and just keep growing more and more roots. Some of the cuttings are in a protected spot in the garden and those tend to leaf out a bit earlier but by June they are all about the same. I put some new babies - still in pots that came from Tenn. in. I was not sure how much cold they could take so to be safe, I brought them into the basement. If they are inside, occasionally check to make sure they have not completely dried out. They need slightly moist soil - not too wet and not too dry..... I also do NOT fertilize until they are potted up and then very little - if any - is added to the pots.

Some of the cuttings are in a very protected spot in the driveway, right next to the bulkhead and that spot seems to be fine for most cuttings. If we get a really cold snap they could be brought in but it would have to last for several days. The driveway is on a good slant so the drainage is perfect for the all the rain that we get.

luis_pr(8 Hurst, TX)

you are right Nikko Blue is not resistant enough to Zone 5b same like Summer Endless (blue) cant flower in my place 5b. I am planing to keep them in containers much easier for me and easier to control colour because I prefer blue colour, Thank you very much.

illsstep(6a)

I would keep them longer in cold room but I got this so called "Winter Blues" ? and my head could not handle it any more so I wanted to speed up spring coming, winters drive me nuts. My basement cold room is about +2 to +8 *C . Thank you very much

ophoenix(8b PNW)

You are lucky you leave in nice climate place, I would love to grow blue coloured hydrangeas without winter prep

I agree yovan..sometimes I hate where I live..

I would not bring them into your living area. You may do better with them on a heated mat (appropriate for plants) and overhead lighting in a month or two. The mat would provide warmth for the root system. Good roots are key to a healthy plant.

Of the Woods Hydrangea and Peony Farm(5-6)

Thank you very much for the advice, I will try to leave them in cold room to hibernate