Mirabilis jilapa

KeenOnGreen

I hope to over-winter these in an unheated greenhouse.  Do i just leave them in their pots and avoid watering till next Spring?

Obelixx

Yes.  Water them well once you've moved them - so they're not too heavy - then let them drain and leave them till spring.  You could put a mulch over th etop for extra insulation once they du-ie down and, if the pots are small, wrap the pots, but not the plant, in bubble warp for a bit more protection.   

They should be fine as long as it doesn't get below -5C in there.  If you get a really heavy frost forecast, protect them with a couple of layers of fleece over the top but held off the plants with canes or some other support.

KeenOnGreen

Thanks @obelixx   Sounds similar to the process I follow for some of my other tender plants