What to do with container plants before winter arrives

With the approach of winter, it's time to start thinking about what to do with all those plants in containers: some can be salvaged and stored for winter while others won't survive and should be dumped. Here are some tips to help prepare your container plants for the cold months ahead.

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The first few autumn touches of frost spell the end for most annuals grown in containers. They are best dumped onto the compost heap, potting soil and all. Then what?

• After dumping the annuals, give the empty pots a good scrubbing with a solution of soapy water and household bleach, allowing them to dry before storing the pots for winter.
• Cleaning the pots is essential to ensure that any plant diseases that could have been in the soil are scrubbed off. It also means the pots will be ready to use next spring and not encrusted with the previous year's hard-to-remove dirt.

Ideally, you should store the pots in a place where they will not freeze.

• Pots that are kept dry and protected from ice and snow can usually withstand the cold without cracking or splitting.

If you've been growing potted hardy perennials, trim back the dead foliage with sharp pruning shears and move the containers to a place where it is cool enough to foster dormancy, but not where plants are subject to constant freezing and thawing cycles.

• Depending on your hardiness zone, it may be sufficient to place the pots against a wall of your house or beneath a bench, where they'll be protected from the wind.

For tight storage spaces

Should your house be tight for space there are other ways to shield your container plants from the ravages of winter.

• If your storage space is limited to a deck or a patio, place dormant potted perennials in an insulated, foam picnic cooler tucked into a protected corner and cover the pots with several centimetres of loose, fluffy mulch, such as evergreen boughs.

Insulation alternative

You can also use plastic bubble wrap as pot insulation.

• Simply wrap it around the outside of individual planted pots and secure it with water-resistant tape, or stuff the bubble wrap between and over the top of a group of stored containers and secure it with tape.

Leave hardy shrubs and trees outside

Hardy shrubs and trees usually need to remain outdoors in winter, because prolonged exposure to warm, dry indoor air is as stressful for them as hard freezes.

• Move your hardy shrubs and trees to a place where they won't be tortured by winds and be prepared to move them indoors for short periods of time in extreme cold.
• Even if light levels are low, it's usually better to store hardy evergreens in a cool garage or storage building over winter than it is to bring them into heated indoor spaces.

Watering requirements

Keep the soil around the roots of container plants lightly moist by watering once a month, but do not apply fertilizer to these or any other dormant plants until early the following spring, just as they begin to send up new leaves.

• Give similar treatment to hardy bulbs that you pot up in the fall.

Moving container plants

Most daffodils, hyacinths and tulips need at least six weeks of chilling in early winter, after which they can be moved to a less frigid place as they start to grow.

• Wait until you see green shoots poking through the soil before you shift them to a spot on a warm windowsill indoors.

While container gardening is more convenient for most people, winter always brings a bit of work to ensure your annuals are dumped and your perennials are stored properly. These tips will ensure your pots will remain intact for next year and your perennials will survive the winter.