After a long cold winter, gardeners are itching to get some color outside, even as early as St Patrick’s Day. Most hardy annuals tolerate light frosts, but not freezing. St Patrick’s Day marks the start of my container season. Including edibles such as kale, lettuce, and spinach gives my containers double duty. And the leafy greens are attractive too.
I use the following cold hardy annuals:
Pansies/Violas-technically not an annual, but I treat it like one
Calendula-great orange and yellow color
Lobelia-a small flowered blue or white trailer that is a non-stop bloomer. It creates masses of flowers that cascade or trail out of a container
Alyssum-honey-scented white or purple trailer
Dusty Miller-good foliage foil with felted grey leaves
Nemesia-comes in a variety of colors and the scent is fabulous
Ranunculus-multi-petaled flower which loves the cold; looks like a rose
Snapdragons-upright flower used for height, seen in cottage type gardens
Ornamental Cabbage-Yes, this looks like a full grown cabbage!; Great foliage in pinks, greens, and whites
Dianthus-The quintessential cottage flower, pinks are treasured for their blue-green foliage and abundant starry flowers, which are often spicily fragrant. They come in pinks, whites, and reds and are sweetly scented
For an excellent chart of frost hardiness of annuals, go to Cold Tolerant Annuals a publication by the University of Minnesota. If anyone knows cold, people who live in Minnesota do! Some flowers can take ice and snow, like Ornamental Cabbages and Pansies; others can take a light frost and temperatures in the thirties, like Nemesia.
Lasting for 6 to 8 weeks, the containers will have run their course by mid-May, and it will be time to plant for the summer using heat tolerant plants. Most people wait to plant their containers until May in the mid-Atlantic region when the danger of frost is past. But why wait? You are missing out on all the wonderful cold hardy varieties that will be done in by the coming heat, like Ranunculus and Violas.
Ranunculus is actually a corm, a small type of bulb, and the flowers look too perfect to be real. Exquisite, rose-like blossoms, they are often seen in wedding bouquets. Silky petals are layered like a rose in bright, paint box colors.
Buying my plants from a variety of sources- big box, wholesale nurseries, and independent nurseries with a good selection – I hold my plants in my cold frame. Staying about 10-20 degrees warmer than the surrounding air, it is convenient to stash the plants somewhere and to look at all my color combos before planting. Sometimes, when I place them in my cold frame without any thought for color, a new pairing of texture or color will leap out at me. If you don’t have a cold frame, storing in an unheated garage or shed will work too.
It is really important to acclimate your annuals to the cold by gradually exposing them to colder temperatures than the warm temps in a greenhouse.
Using accessory elements like statues, balls, and twigs, will make the container pop.
Having flowering plants out in March and April is extremely important for the pollinators that are flying in chilly weather and have trouble finding nectar sources. You are providing a vital source of nectar and pollen for these important native bees by planting out early, as well as giving yourself a boost of color therapy after our cold winter.
Trailing white Alyssum makes this container look lush
Perennials like Coral Bells, Carex, Bergenia, Hellebores, Scabiosus, Lamium, and Evergreen Ferns, can be used in the early spring container as accents and fillers. The worn out annuals can be pulled out leaving the still performing perennials and newer heat tolerant annuals inserted in their place.