Is it safe????

I have just bought a couple of root Paeony's for a fiver and have now put them into a large pot for the time being. I just want them to grow as the last time we tried this they did not do so well.
Asda are selling them at 2 for a fiver, the ones we got are called Sarah Bernhardt, which is a lovely pinkish white.
They have been placed in compost so as the top of the root is just about surface level and have watered them in.
Now the trouble is I am not sure if I should place them in the greenhouse to protect over night or not.
Weather being on the cold side at the moment would suggest that I do keep them there as the cold frame is to cold.
Having had this plant in the last property, which had been rotovated and dug through prior to showing itself one year, we fell in love and have been trying to grow them ever since.
We have got roots, plants and still no joy, from what I can gather we have to wait a while to get any decent growth from the plant and even longer to see it in flower.
Could somebody point me in the right direction of getting the best from this plant Please?

 

Trouble is Marley, weather on a downer again. Looks like frost at the weekend again for us, I have put them into a large pot for now and hope that when the time is right I shall transfer them to the spot in the garden which will give them the best aspect.
Also, I shall incorporate plenty of sand and compost to the hole before I put them in as they like a light free draining soil. We have claggy clay here and it is so hard to break up.

 

I have 'Sarah Bernhardt' as well Landimad and paid £1.20 for it. I potted it up about five weeks ago, meanwhile digging out the new bed it's to go in. I kept it in the greenhouse hoping the extra warmth would trigger it, last week when it's first shoot appeared I moved it to an open porch to semi harden it off. I will plant it out next week but I don't expect it to do much this year though and it will make up root growth if nothing else.

 

If I can just get things to grow here then I would be a bit more enthusiastic about the garden.

 

Yippee, I have new growth on both of the roots. I shall keep an eye on them to see if there is a need to move them or leave them where they are for now.

 

I bought a Sarah Bernhardt last year which I shoved in a smallish plastic pot with some compost. Got some leaf growth last year and it's been in the same plastic pot outside over winter and has rewarded me with a single flower this year (not opened yet but nearly there)

I do plan to plant it out somewhere but haven't decided where yet.

 

I have a Sarah Bernhardt and I think it has been quicker to settle and start blooming than the other peonies I've had. It is almost more lovely in the shoot and bud stage than when it flowers as they are very top heavy and need support. Great for cutting, though, I have some on the mantelpiece right now. I love the way ants crawl all over the big, round buds - I believe this helps them to open, it happens every year.
They are extremely tough and hardy so if the ground is ready I think you could plant directly at most times of year.