There are two types we are familiar with and prefer the low expansion type. Additional container planting information follows below. Gardening isn't just for the country and suburbs. Many of us in cities that would like to have gardens, have stuck to annuals shoved in pots to improvise gardens - and that's nice, but it somehow feels a little like a wax flower until it develops a history.
Potted perennials can give that essential permanence that is so necessary to feel real.
The following is a brief list of perennials that will reliably repeat in containers of an average size. The ability of clay to breathe may cause a faster loss of moisture which is not preferable. Plastic or any other material which does not breathe is ideal. Plants that are now in clay pots will be fine if you water them well before they freeze. If you intend to leave plants in their pots this season, you do not really need to transplant them to plastic containers at the end of this coming season, just wrap them in plastic and all will be well.