March 20 marks the first official day of spring. As ice melts and soil thaws, the Arboretum’s horticulturists ready for the growing season.
Once snow is gone, crews can reach the ground and prune those shrubs that have hardy roots, but delicate stems such as beautyberry, butterfly bush and bluebeard. Known as rejuvenation pruning, this practice requires all but six to 12 inches of the plant to be removed to allow for more vigorous new growth.
Mid- to late-March is also the time to start working the soil, though Abbie Rea, manager of horticulture, cautions against digging in when soil is still wet from past snowfall. Arboretum staff will use this time to tidy the edges of garden beds. Gardeners can create a crisp line dividing the soil of a garden bed from the rest of the yard by using a sharp square spade along the rim. Clumps of turf that arise are perfect for the compost pile.
Then comes a light layer of mulch.
“This way when the garden wakes up, it is ready to grow,” Rea said.
When it comes to planting, the Arboretum staff holds off until the first week of April or even later if the forecast is still cold. Certain flowers such as pansies can tolerate some frost and cooler temperatures—as low as mid-30s by night. As the days warm, gardeners can expect to greet the first of the spring bulbs that were planted in the fall. These include tulips, daffodils, anemone and scilla.
Early April is also the time for vegetables that can handle soil temperatures below 50 degrees. Cool season veggies include celery, lettuce, beets, peas, onion, radish and kale.
As spring progresses, our experts turn their attention to shrubs that need pruning after flowering, such as white-forsythia and viburnum, to ensure they’ll remain vibrant in future years. They will also deadhead some flowers, such as daffodils, once blossoms have faded to accelerate the return to dormancy for the following spring.
Look for these blooms all around the Visitor Center and Children’s Garden as winter melts into spring and turn to The Morton Arboretum’s Plant Clinic for your plant concerns and questions.