Ideas on overwintering plants?

I'm not sure if this is the right section to post this. Sorry if it isn't.

Living in a rather snowy climate, there are many trees, perennials, and bushes that cannot survive the winter in this zone. Bringing them indoors is not a viable option for me at the moment due to limited space, and it seems the most useful varieties are also the most delicate. I've tried looking online for ideas on what to do, but everyone just recommends mulching the roots deeply and covering the top with a commercial frost blanket. Obviously this isn't a cost-effective or sustainable option. Anyone have any ideas on how to lower the temp around a plant by at least 1 zone/10 degrees?

Thanks all.

You can plant near a house wall or near a huge water tank. You can mulch thickly. You can construct or plant windbreaks.