If you live in areas of the Southwest that freeze in winter, you’re already beginning to empty and clean out containers and deciding how to preserve your annual flowers, herbs and other container plants.
Move containers with hardier plants to a warmer exposure
Although a plant might be listed as perennial in your growing zone, the roots of container plants get much colder than roots of your perennials in the ground. Any plant hardy to your growing zone might only be hardy to a half-zone or zone higher (warmer) if left in a container all winter. For example, I am in zone 6B, and there are rosemary plants hardy to zone 6. In some winters, they have survived in containers, and in other winters, they haven’t. If possible, move containers to an area with full sun (southern exposure) and near the house or hardscaping, such as paver walls, that will help absorb and retain heat and cut wind exposure. You also can insulate containers of prized plants with bubble wrap or mulch (with a simple netting or other way to hold the leaves or straw against the container).
Take plants inside
Other plants are snowbirds – they live outside in summer and inside in winter. Not all plants thrive indoors, but succulents, geraniums, begonias and fuchsias can. Before bringing containers inside, check for insects. If it’s a warm, sunny day, you might spray them lightly with a hose and let them dry for a few hours before transferring indoors. Or transition the containers by first bringing them into your garage and then into the house after a week or two. You can check for hijacking insects and ease them into the indoor environment. It might help to hit tropical plants with a light spray of water daily for a few weeks. I worry less about that in the Southwest because our humidity already is low outside, and we use less forced-air heat than some climates. Gently trim geraniums and similar flowering plants to conserve their energy and help support winter blooming in a sunny location.
Replace heat-loving flowers with cool season edibles or pansies
Many heat-loving plants survive in warmer Southwest gardening zones for year-round interest. In moderate Southwest locations, you also can replace annual flowers with cool-season vegetables in containers throughout fall and even into winter. I love having lettuce and arugula right outside my door, although I only can grow them in spring or early summer and late summer to fall. But where nights are warmer, kale and other greens can survive in containers, as can peas if you have a spot for trailing.
In colder areas, pansies are the go-to winter plant for color. Their name defies their toughness. Most pansy varieties survive frosts; even if the blooming flowers burn, the plants survive. Cheer yourself up by planting pansies in your front entry or back patio container for winter color.
Empty, clean and stack unused containers
I have put off cleaning out containers too many times. We all seem to lose our enthusiasm, especially for chores like that, in fall. But it is better for the container life, and to ease the spring burden, if you empty potting soil from containers before it dries and compacts. You can save potting mix from healthy plants in a large bucket and reuse it for filling the bottom of next year’s containers (adding fresh compost and potting mix when you plant in spring). We often empty our potting mix into wheelbarrows and transfer it to beds that are compacting or as fill dirt in raised beds. We’ve never transplanted insects this way, but have had surprise cosmos and portulaca flowers pop up among potatoes in summer. Stack unused, clean containers in a shed, garage or protected area to extend color and life of the pots.
Increase sun exposure for indoor containers
Even plants commonly grown inside might need to move further from a window’s draft but in as much winter light as possible. Those that do well with eastern exposure in spring and summer might need a dose of southern sun in winter. However, too much of a good thing can harm even succulent leaves, so keep an eye on all plants on window sills. It is a good idea to move or rotate the plants, and maybe move them a little further away from the window. We get some exercise moving succulents and violets around to follow the sun through our southern windows each year. The least amount of light typically falls on your windows in spring as days are shorter but the sun’s path is rising in the sky. This might be the time to place or rotate plants in and out of grow lights.