Overwintering Gaillardia & Dahlia in containers
First foray into both these plants this year (both of which we have enjoyed immensely) and we previously just left everything in the pot outside in the hope that it will pop out again in spring (with mixed results as you can imagine!). However I want to take care of these so would I be right in thinking I would be better off cutting them back fully after a decent hard frost and then moving the containers into either a small greenhouse (which could be heated) or an unheated garage? If so which would be best? Thanks in advance!
Gaillardias are hardy I think - although it may depend on the variety, as not all of them are perennials. Assuming it's one of the hardy perennials, they should be fine, although I'd keep them against a sheltered wall somewhere so that they don't get too wet/frozen as they're in a pot.
They tend to be short lived perennials, so many people would take cuttings of them at some point. That would probably be best done in summer, but I'm not sure on that.
I live in west central Scotland - not where that photo is...
S & W England and S Wales : Gaillardias: as above as an insurance policy. Otherwise, levae them out, but cover with transparent plastic to give them both light and to keep them dry. Same thing for Dahlia tubers, but no need for light, so compost will do. Lift a few as an insurance policy. Remember the old maxim " Cold and wet, send for the vet."
Are there any disadvantages to cutting them back and lifting them before a frost actually blackens the foliage.
You always see it mentioned to wait until then but I've yet to see a reason.