In the main if things are outside in pots Ive always found its best to leave it to nature,never had any problems that way,whereas if you get watering and it freezes,since water expands upon freezing, you could end up cracking pots etc your bulbs though since many appear very early, may want some help perhaps,especially if its been very dry,be guided how you feel at the time,unless they are bone dry then they are probably ok (Im talking about the bulbs here of course) everything else I just leave well alone till about the end of February,then I might water if its been very dry (unlikely) as things are now starting to move again slowly ...in the past if I have moved stuff into the greenhouse for a bit of extra protection,I have still found they retain enough moisture right through the Winter as they are dormant anyway .....hope this helps ...take care
On the other hand you might want to be guided by this copied from another site
First, it is EXTREMELY likely that pots made of terra cotta, clay or any other heavy, stone-like material will indeed shatter if left outside over winter. When the soil inside freezes and thaws, it cracks the poor pots wide open. I’ve even lost EMPTY pots left outside during really severe winters. So lesson #1: Don’t leave stoneware containers outside over winter if you’re gonna get all whiney when they break.
Second, there is a strong possibility that plants left outside in any kind of pot in areas where the temperature drops below freezing will die. Pots simply don’t provide the kind of protective insulation for those roots that being buried in the soil does. And you ladies can’t use the trick I detailed last week—bringing peppers, impatiens and other tropical plants indoors to provide color in your home over the winter—because the plants named in this week’s questions require a certain number of hours of winter chilling to flower correctly, OK?
Now—here are your four basic potted perennial plant options for winter.
1) Plant the plants. Even if you intend to dig them up again in the Spring, these kinds of perennials do best when their roots are tucked into good old garden soil over the winter. (And now through fall is the perfect time to plant!) Just take them out of their pots and put them in the ground anywhere you can find that drains well. If there’s absolutely NO room at your place, ask a friend or relative if you can plant them at their house for the winter. Plant at the same depth they were in their pots, and water them well. Water once a week from now till frost if we don’t get any rain, and again if we go a month or more without moisture over winter.
2) Plant the pots. Again, not if they’re terra cotta. But plastic pots can be ‘planted’ right in the ground. This may seem foolish, but it actually provides all the benefits of in-ground insulation without any risk of transplant shock—and it protects the plants’ roots from underground winter gnawing by voles. Just bury the pots, water as directed above and dig them out again in the Spring.
3) Gather all your pots together, place them against the North or east facing side of your home and cover them a good foot deep in shredded (NOT ‘whole’!) leaves after the trees give up their previous “Fall Gold”. To be safe, I’d remove plants from terra cotta pots and lay the plants down on the ground sideways with as much soil still attached to their roots as possible. (Leave plants inside plastic pots for that little extra vole—and rabbit and mousey—protection.) Dig them out of there as soon as the weather warms up in Spring and put them back out where you want them. You don’t have to wait until after the last frost—they can take a chill, just not a really deep freeze.
4) Take the pots into a cool, dark place that will remain between 40 and 50 degrees and allow them to go dormant. Water them once when you put them down and then leave them alone till Spring, when you will take them back outside as soon as the weather warms. Water them well right away, and until we get rain......