Surrey,
United Kingdom 
Would you say that if you go away for months in winter and haven't got a proper greenhouse a garage with one small window will do? can most perennials do with lack of light I left my plants this summer for a month pre-watered in garage and found that they didn't dry out much.
6 Oct, 2018
Answers
For a couple of weeks, maybe OK. For a couple of months, or more, they are going to be starved of light and dried out. Overwatering in summer is fine but in winter a hard spell will likely freeze the pots, even in a garage. As Bamboo says, a sheltered spot outdoors is much better.
6 Oct, 2018
Light wouldn't matter much if they are deciduous would it?
6 Oct, 2018
Depends how many months, Steragram - plants are stirring beneath the soil in response to increased light levels during February, sometimes earlier, not to mention they might dry out completely inside. Without knowing the time span, this is impossible to answer properly....
6 Oct, 2018
Goodness. How can they tell there are increased light levels when they have nothing above the ground? Nature never ceased to astonish...
7 Oct, 2018
Well, I should have said increased light and warmth levels ...too subtle for us to notice, but plants do.
7 Oct, 2018
Tender plants that can't take the cold away for about 3-4 months I found in the past geraniums,brumansia, salvias can be left for long periods without water in fact watering will rot the plants just my experience anyway
7 Oct, 2018
If those are the sorts of plants you mean (tender perennials) then you;ll have to put them in your garage, failing a cold frame or greenhouse. But my garage is usually colder than outside in the winter; after a cold night, it still tells me its -4 deg or something at midday when its 7 or 8 outdoors. Pelargoniums (I assume that's what you mean by geranium, not actual Geranium) withstand up to 10 degrees of frost - it is, indeed, the combined damp/cold that kills them here.
7 Oct, 2018
Interesting to learn that it can be indeed colder in the garage than outside indeed I have in the past many bulbs/tubers rot out even when left airiated in netting in the garage..l find new buys usually suffer death in winter I was a sucker for buying plants at summer/autumn plant fairs like great dixter only to never see them again
9 Oct, 2018
What's wrong with just leaving them clustered together outdoors in a sheltered area, if the pots are good sizes? Are they tender perennials? And what does 'months' in winter mean- October to end of March? less?
6 Oct, 2018