I have, at last count, more than 50 container plantings on various terraces, porches and decks around our house.

And while the plantings themselves may change, the pots are reused over and over again. It's a great system - until, of course, that inevitable day when your terra cotta, ceramic and/or cement pot cracks, flakes or breaks completely into pieces.

In harsher climates, gardeners simply empty, clean and sanitize before storing the pots in a basement, shed or garage that never dips below freezing.

That isn't necessarily feasible here in Western Oregon, where gardeners want or need to keep some of their more mature container plantings outside over the winter months. Potted trees and mature shrubs are typically just too darn big and unwieldy to even consider moving, unless you are gifted with a stately greenhouse - and hired muscle!

That said, outdoor winter temperatures do dip below freezing at various times between late October and April. Sometimes it's just overnight. But on occasion the mercury can linger in the teens and 20's for days at a time. This type of stress, especially when the cycle seesaws between freezing and thawing, is tough on plants and extremely challenging for containers.

With inexpensive terra cotta planters now widely available, it's tempting to indulge in a variety of shapes and sizes. They're relatively lightweight and the natural clay looks terrific in any setting.

But terra cotta has an insidious enemy: winter moisture. Add a freeze-and-thaw cycle (or two) and the resulting expansion and contraction can weaken even the strongest clay pot.

Drainage is critical if terra cotta planters are going to last more than a year. Water needs to drain from the pot and away from the pot if the clay is to stay relatively dry. All pots should be up on pot feet.

Pick a time (I always try for the weekend after Halloween) to give outdoor containers and their plants a grooming. Trim back perennial foliage; remove whippy branches from trees; add a slow-release fertilizer if you'd like. Water one last time.

Wash dirt and slime from the outside of your pots, then dry well. Have on hand a large roll of bubble wrap (look for it at your favorite office supply or packaging store). Dry the sides of your containers again, and then wrap the outside of the container with an insulating thickness of bubble wrap.

Allow the wrap to rise three to six inches above the sides of your container. After taping it secure, fill the inside with cocoa hulls or shredded autumn leaves for added soil insulation.

The idea is not only to protect the pot, but also the plant growing inside. Remember: during the winter months, the soil inside of a container becomes colder than the soil in the ground - approximately one zone colder. I've lost plants that are normally hardy here simply because they were grown in a pot, with nothing to buffer the root system but a thin layer of Italian clay.

The folks at Urbanweeds, a modern and environmentally friendly garden shop located outside Seattle, Wa., adore terra cotta pots and refuse to give them up during the winter months. Despite their location (it's even more rainy and often colder), they rarely have problems with cracking or flaking terra cotta. How do they do it?

First, it helps to review the physics. Water expands as it freezes, a phenomena exacerbated by poor drainage. The force generated from on-the-way-to-being-frozen water-logged soil can easily burst a clay pot.

So, how best to remedy this problem?

n Elevate! The Urbanweeds experts agree that getting a pot even an inch off of a deck, stone terrace or concrete patio is the easiest method of keeping it from freezing.

n Add air! This gives freezing soil room to expand, thereby reducing the likelihood of a burst container. Simply line the bottom of your pot (during the initial planting phase, or during repotting) with two to four inches of styrofoam popcorn or packaging material. This creates air pockets which the frozen soil can essentially freeze into.

n Finally, do bundle. Bubble wrap, hay bales, mulch - whatever you use, the idea is to keep your container just toasty enough that it does not crack, flake or disintegrate.