Yes.....I did the same with a couple white Agapanthus I bought last week.....?Out in the day, in the greenhouse at night.
I suppose it's a good idea to harden off all our plants before planting , just in case they have just come out of a poly tunnel or similar.

Very difficult one Diane. There are lots of plants imported from Holland that are grown 'soft' in polytunnels. A giveaway is the labels are often in several languages. It is best to buy from British growers who usually harden their plants off outside before supplying our garden centres. You can look out for labels such as Hilliers, Farplants or in some cases they will have a 'grown in the UK' label. But if in doubt then why not ask when purchasing as their buyer will know where they come from? If still unsure as Paul says, we will have to harden them off ourselves as a matter of course when the temperatures are still quite low.

I think the only way is to ask yourself 'would I expect to see this plant in full bloom in a garden at this time of year'. If it appears to be wonderfully early then it has probably been grown in a tunnel.

Thank you all for the good advice. I hope other members read it and remember. I have Dianthus in full bloom in
my garden, probably after15 years they are now used to
the North winds we get here. Although Bathgate has this theory that strong winds strengthen plant stems. My old Dianthus proves this is true.

Another point is that its often better to buy hardy
perennial plants from the little stalls at open gardens, or charity events.
They have been grown locally, and put out for weeks as space is needed in the grower's frame.

Buying from garden centres I'm also guided by whether plants are out in the open or under cover or even indoors.

Thats not such a good idea Urbi. They will not harden
just by being stood on staging outdoor for a few days.
My Diathus was under cover.
Might as well have spent the money in Sainsburys.

But by my method, the dianthus wouldn't have gone straight outside when I got it home.

Today at the GC I asked to speak to the Manager. Didnt realise it was a joint appointment.
Man came forward. Listened to me. Said as expected
"We havent had any other of these plants brought back."
(usual tactic - no one else has complained, only you)
I explained that if the plants are grown for months in polytunnels, then brought over to this country, bought as hardy plants and put outside in the cold winds we had recently, they will suffer, and show it.
Therefore there should be notice on the stall stating that these plants are not fully hardened, and should be placed
indoors at night. (I still stick by this.Customers have a right to be informed.)
He said he would tell the other manager as she does the
buying. He thinks the Dianthus plants came from Belgium.
I repeated that I am putting this plant (£8) in the greenhouse at night, and outside in the daytime.
He said he thinks they came from Belgium.
I repeated that the weather conditions are not the same in this country as Belgium or anywhere else.
He repeated he would tell the other manager.
I said people are not going to buy plants from this GC if they have this experience.
He said he will tell the other manager.
I said I had reported this matter on the GOY website,
so if he reads it he will know I have.
The other manager should tell the grower these plants should be hardened off before being sent to this country.
Diane

I think it may be more than simple hardening off.....Danthus are a large group of plants, a couple of years ago I bought some.....one I remember was called 'cherry pie' it was lovely and died in the winter....(in gritty soil)

Then last year I changed my patio pots to perennals rather than bedding plants, I specifically asked for dianthus that were bone hardy, I was thinking of pinks etc but not too tall....

All except one died over the winter, the compost is open and gritty... theone that survived is magnificent its pink and has filled the very largest of blue glazed pots...not a space to be seen.....

On none of the labels was hardiness mentioned, only sun or shade....that in my opinion is where the problem lies....

Well, this all goes to prove that the customer has a right to be informed by the garden centre staff. A proper notice
should be displayed by any plants they are not sure of.
Or they should contact the actual grower, before displaying them. I hope my detailed complaint letter will bring forth some action in this direction.
Customers should complain more often, or go elsewhere.

I can remember a time when £8 was a bus conductor's
weekly wage for shift work. Nowadays its spent on one plant that is chucked out when two thirds of the flowers drop off.

Or "Nobody else has complained, only you." Thats what
annoyed me.

Diane, just as an afterthought, if your garden centre is a member of the Garden Centre Association, then they will have a hardy plant guarantee. Some are for 2 years and my local garden centre guarantees their hardy plants for 5 years.

Good point Jimmy, I take dead things back to Wyevale....or send a photo to customer care.......always courteously replaced.....
managers don't like dead plants in the gc!