Garden centers are awash with pumpkins, mums, pansies and kale in celebration of autumn. If your potted plants are looking a bit tired after a hot summer, now’s the time to pop in a few fresh ones to carry the display until the cold weather settles in.
“This is a peak time for color,” says Ingrid McGuire, container gardening expert at the Chalet Garden Center in Wilmette, Ill. “We sell a lot of the Pelee mums (Chrysanthemum x morifolium ‘Pelee’), and they start out red and go to orange, gold and then yellow.”
She’s also planted perennials in containers. “I like Heuchera, yarrow, coneflowers and Rudbeckia. I like to focus on a lot of texture and fall color. There are a lot of new Heucheras coming out in beautiful colors like caramel, deep purple and rust.” For other colorful foliage, McGuire may include common or golden sage or ‘Chocolate Chip’ ajuga. “I’ll start with two main plants – something that strikes my eye or is unusual – and I’ll build around them.”
There’s a short window of time before very cold weather, McGuire says, but there’s a bonus to refreshing fall containers – it’s less work. “You don’t have to fertilize plants in pots or remove the spent flowers, except for pansies. Remove finished pansy flowers, so they’ll continue to bloom even when the temperatures drop.” And, because the air temperature is cooler, plants are not as stressed by hot weather when they quickly wilt without water.
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One of McGuire’s favorite combinations is white ornamental cabbage with Redbor kale. “As the temperatures get cooler, the kale turns dark purple.” Kale and pansies can tolerate cooler temperatures, frost and even a light snowfall. “They’ll be fine,” McGuire says. “A hard freeze is a different situation.”
The Chicago area tends to see its first fall frost – the formation of thin ice crystals on the ground and on plants – about mid-October. According to the Illinois State Climatologist office, a temperature threshold of 32 degrees is used for frost and 28 degrees for a hard freeze. You can protect your containers on cold nights by covering them with one or two large garbage bags or with frost cloth, which is sold at many garden centers. Covering the plants can keep the surrounding air temperature as much as three to five degrees warmer than the actual temperature.
Joliet, Ill., garden designer Patti Kirkpatrick refreshes her containers of edibles. “I like to fill in empty spots with perennial and cool-season herbs such as sage, oregano and parsley,” she says. “Greet your guests with a taste of things to come in your holiday feasts – use the herbs in your cooking as well as fresh fillers in a centerpiece for a beautiful table later this fall.”
Kirkpatrick also uses twigs to give height to pots. “I add curly willow branches that can be used natural, or you can spray paint them.” For texture, she adds cut flowering stems of ornamental grasses. “Panicums (native switch grass) work well, as do Calamagrostis (feather reed grass) and some Miscanthus. And yes, you can spray paint them all too.”
When designing fall containers, McGuire looks to plant combinations that offer contrasting foliage and texture. In the center of a pot, she may use Toffee Twist sedge (Carex flagellifera ‘Toffee Twist’) because of its beautiful toasted coppery brown corkscrew leaves. “It makes it much more interesting than just flower color – I just love it.” You will too.
The pros share these fall container gardening tips:
Fill in the blanks. Where there’s an empty spot in the container, Kirkpatrick says, “Plop in a real pumpkin or two for color.”
Wait for the display. For long-lasting chrysanthemums, McGuire suggests buying plants when the flowers are just in the bud stage, so you can enjoy them as they open.
Free them from the cabinet. “So you no longer use those turkey salt and pepper shakers that belonged to Aunt Mildred?” Kirkpatrick asks. Remove the plugs on the bottom, place the shakers on a stick and pose them in a pot. “Pilgrims and pumpkins work well too,” she says.
Use perennials. “You can take them out of the pots and plant them in October in the ground, so you can enjoy them next year,” McGuire says.
Anticipate the winter. As the weather gets cold, replace the plantings with evergreen boughs, Kirkpatrick says. “But leave the curly willow and herbs in the pot. If you use fresh curly willow branches, they may even root in the pot. You just may be surprised next spring.”