Container gardens offer option for the season
They're on sale now, big time. Even while restocking for fall planting, some garden centers have marked down trees and shrubs to irresistible prices. So many trees, so little space. How to snag a sale when your garden overfloweth?
"You can plant them in containers," suggests Abbie Rea, the Morton Arboretum's assistant manager of horticulture. "It's a way to focus on something traditionally out in the landscape and bring it to your front door."
At the arboretum, there are nearly 50 container plantings adorning the Visitor Center and Children's Garden alone. Along with unusual mixes of trailing plants and eye-catching annuals, you'll find containers with tree and shrub varieties such as dogwood, ginkgo, maples and willows.
There are many uses for trees in containers - and let's stipulate right away we're talking about small, young trees. Trees can bring interesting height and structure to a container planting that simply couldn't be achieved with annuals and even vines. Containers are also a temporary solution to house trees or shrubs until fall or when planting conditions are optimal.
With protection, some trees and shrubs can be overwintered in their pots to rebloom again next spring. And - the Holy Grail of potted plants - some can even survive in pots outdoors during winter.
Twisted willow (Salix erythroflexuosa) stands up to our winters and showcases interesting spiraling branches after its leaves fall. Red twig dogwood, a deciduous shrub with brilliant scarlet branches also can survive in a pot outdoors. Conifers such as weeping spruce and false cypress (Chamaecyparis) will enhance your entrance year 'round.
Plants that need to be overwintered with protection include many shrub roses, dwarf pines, boxwood and hydrangea. During the growing season, their foliage, blossoms and shape will add interest to any container. Before the first hard frost, move the potted plant into a sheltered area such as an unheated garage where the temperature will remain between 32 and 45 degrees.
For these overwintered plants, Rea recommends using bubble wrap around the bottom of the pot, and burlap covering the top for extra insulation. Water during the winter about once a month. Overwintered potted plants are often less vigorous than their in-ground counterparts, so don't expect them to last as long. Yet, if bought at a good price, these woody plants could even be a less expensive alternative to buying new annuals for containers each year.
Plant selection and care are just as important for any container tree or shrub as in the landscape. Of course, if you plan to leave your container outdoors, the pot itself should be winter-proof, and harmonize with the plant.
"The tree or shrub should be in scale with the planter," Rea cautions.
Trees and shrubs can be kept in the nursery-provided plastic pot within a decorative container. Prune any roots sticking out from the bottom.
"Hide your mechanics," Rea advises, noting that the tops of black plastic pots can be cut to size if taller than the container. Cover the top of the soil with mulch to retain moisture and further camouflage utilitarian pots.
Choices of woody plants for containers depend on your plans after the growing season. If you intend to plant the specimen later in the landscape, your choices are virtually limitless. Rea likes sweet bay magnolia for its "great foliage." Plum and cherry trees have great structure and spring blossoms. Kousa dogwood flowers in late spring and offers interesting fruit.
The arboretum even displays young ginkgo trees in containers. Not every home can sport a mature ginkgo, which can grow to 150 feet. But a young one in a pot is surely striking - as long as you remove the sale tag.
• Cathy Maloney writes for the Morton Arboretum. Her column appears monthly.