Question
Hi! Am in zone 5/b. Have a balcony that is  exposed to the west/north/east [boo hoo]! Have failed @ over-wintering my perennial container plants; and so I mostly grow annuals! Can you please tell me just how I should do my next over-wintering attempt?

I know:
1. to mulch w/leaves/straw ect.. surround  
all with; say, black plastic bag/bubble wrap
2. can wrap pots in burlap
3. use as large a container as possible
4. provide as much shelter as possible
5. try to grow stuff 2 zones lower
6. tilt pot at an angle

Have thought to build a wooden surround [NO bottom to it?] for the perennials - fill in spaces with leaves and mulch with chopped up leaves. Also have some thick pieces of styrofoam that could also be used to surround containers.

Have read to try to keep water/snow from getting into containers? - to help with: freeze/heave.
Have no ground space to "plant" pots in --- do have a cool/dark entryway!

Have only been gardening for 6/7 years; have tons to learn!

Thank you for any advice! Ann  

Answer
Shelter is very important. I have all of my winter perennial containers on a covered deck, against the house.
The thing to understand, is that container soil is colder then the soil in the ground. It will freeze sooner, and stay frozen longer. Many of the things you have on your list are things I would suggest. Insulating the pots with the things you have listed helps. Set small pots inside larger pots with soil or other fill. Many people use the garage, or basement to store plants over winter. The cool/dark entryway, may be the cover you need to keep the frost off. The light isn't as important in winter, because the plants are dormant. But, they will need to be moved into the light, when the spring temperature heats up.
The other thing is that plants don't like sudden changes.
They like to slowly adjust. This goes for all things, but especially temperature. So, keep that in mind when you watch the weather report on the news. Most damage is done by the sudden freeze you didn't see coming. You can relax a bit when the plant goes dormant. It is sleeping. As long as it has plenty of soil around it, no heaving out of the soil, it will be okay. Keeping the soil on the dry side, will prevent rotting, because it isn't using much water.
That is why it is better to keep rain or snow off of it and just water when it is dry.
The choice of plants is also important. This may take some experimenting, and research.

bakerplanter