put them in a greenhouse or cover them in a transparent plastic sheath to protect them from frost.

my globes are fine just as they are .

My agapanthus, in pots, are always fine....even in -13c of frost.
Never had any problem with them outside.

Hi, welcome to GoY, globe artichoke, or Cynara scolymus, is completely hardy, just leave it alone, Agapanthus is a genus of 10 species, ranging from fully hardy to half hardy depending on which species you have, the deciduous species are usually the fully hardy ones, so if the foliage dies back on your plant, it is probably hardy, if it stays evergreen, it may need some frost protection, having said that I have a deciduous 1, and that hasn't died back yet, Derek.

oh I thought it would need protection but oh well :)