I would look to buy in springtime. Go careful though as they can become quite invasive. Once you have mature plants you can propagate by root division in the autumn.

I agree with Jimmy, Springtime and try to plant them immediately

Never would be my answer.

OB, I have to say that I have planted quite a few in my garden in the last few years but have to admit that this wasn't one of my best decisions as they will take over if left too long.

I have spent 20 years trying to get rid of them. They destroy every other plant in their path and weed killer has very little effect on them. They should come with a Health warning in my opinion.
P.S. I did not plant the ones I am trying to remove, they were already here.

Doubt we would give them garden room, they're thugs!

Even Whirlwind? Just wondered if it is less vigorous - doubles often are? The common pink ones are thugs but my single white Honorine Jobert was always well behaved and I have a Whirlwind ready for planting - anybody with several years experience of this one please help quick! I know Paul has one.

The single white ones are worth having in my humble opinion - and shouldn't spread too much in Linda's clay soil . . .

Love this question!! And the answers, so varied! I agree with OB, we 'inherited' them with the house and can't get rid. Digging, pulling regularly to weaken, weed killer just won't touch them. Little blighters just spread and colonise another area.
They are the common pink ones of course, but wouldn't touch any of the others, unless I have a four foot deep barrier to keep them in place.
I presume Sheila you are only talking of the single white when you say it shouldn't spread on clay. We are on heavy clay, sets rock solid in summer, but it doesn't deter the single pink!

Yes I said "single white" Honeysuckle! (which scarcely spreads at all in our clay . . . )