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Thanks for that advice I too have fuchsia bushes still flowering in the garden, they are years old and obviously hardy. I also have a trough full of a variegated leaf geranium still in flower, that's gone in the greenhouse as well, but as usual I've taken cuttings from them that will over winter in a heated porch. I've kept these geraniums going from one plant for 17 years so I know the cuttings will survive.
I'll keep the watering of the baskets in the greenhouse down to a minimum and will cover them with fleece if it's exceptionally cold (like last winter) and hope that they survive.
Last year a nepeta plant in a tub outside survived the serious frosts, it's replanted in one of the baskets so it'll have another chance this year.