Not many garden plants flower in December. The hardy bloomers at this time of year fall into three categories: a few shrubs that start flowering now, a few perennials (if you stretch the definition of “perennial”) that begin blooming, and perennials that are still blossoming months after they first began.
The Charleston Horticulture Society (chashortsoc.org) recommends tea olive (Osmanthus fragrans) and camellia (Camellia japonica) as shrubs that bloom starting in November. These broad-leaved evergreen shrubs are common in a typical Charleston landscape.
Both shrubs are rather particular about the amount of light they receive. Tea olive needs part sun to grow lush and full; with too much shade, it drops some of its leaves, leaving bare branches. Tea olive also needs protection from “nor-easter” winds in late winter that will blast the very tender new shoots.
Camellias, and the closely related sasanquas (Camellia sasanqua) and dwarf sasanquas (Camellia x hiemalis), need part shade to survive the hot summers. They also need slightly acid soil, so they are well adapted to life under tall pines.
One of my favorite dwarf sasanquas is ‘Shishi-Gashira’ with thickly set, dark green leaves and hot pink double flowers (monrovia.com/plant-catalog/plants/660/shishi-gashira-camellia).
Another shrub that often starts blooming the end of December is leatherleaf mahonia (Mahonia bealei). The bright yellow flowers are a welcome sight on cloudy days. Leatherleaf mahonia is a different species than the better-known Oregon grape holly (M. aquifolium), which is not suited to the hot summers of the Lowcountry.
The herb rosemary is one of the few “perennials” that begins to bloom in December. The small, pale blue flowers that appear at the tips of branches attract honeybees. Paperwhite narcissus, a dependable perennial bulb, usually opens in November and continues for a month. My first ‘Ziva’ just appeared this past week.
The date of the first hard or “killing” frost is one factor that determines how many summer perennials still are in flower at the end of the year. A late frost may not happen until New Year’s Day (2009, 2011), while an early frost (Nov. 19, 2014) shortens the season of those perennials that “bloom until frost.”
The other factor is the typical blooming time. Some perennials, such as Stoke’s aster (Stokesia laevis) or ‘Goldsturm’ black-eyed Susan, blossom mainly in summer and may rebloom in fall. A few others, like lantana or plumbago, never seem to stop, although they may “rest” for a few weeks between blooming cycles.
Based on observations in my West Ashley yard between 2007 and 2013, the following perennials are most likely to still bloom in December.
The two most consistent ones are trailing lantana and Lemmon marigold, also called Copper Canyon daisy (Tagetes lemmonii). They bloomed every December, even when there already had been a light frost. Note that my Lemmon marigold and some of my trailing lantana are located near the garage, where they receive some protection from cold. After frost, the dead tops should not be cut until late February to ensure these tender perennials overwinter.
Autumn sage and ‘Hot Lips’ sage often still have flowers this time of year. Both salvias start blooming as early as the end of March, so they are among the perennials with the longest blooming seasons here.
Dwarf coreopsis (Coreopsis auriculata ‘Nana’), also known as dwarf-eared coreopsis, blooms sporadically during the later fall and winter, even though its main blooming time is spring. This diminutive perennial grows only a few inches high during the winter; when the weather warms, the leaves grow taller (4 to 5 inches). It is tough and long-lived. If it gets leaf spot in the fall, lightly rake the dead leaves off in late winter and dispose of them.
Finally, bottlebrush, both full size and dwarf forms like ‘Little John’ or ‘Compacta,’ still has a few flowers in December about half of the time. As with the other plants mentioned, its main show time is May to June, but it continues to bloom sporadically whenever it produces new shoots.
Plants that bloom in December may not have as many flowers as during warmer months, but growing flowering plants 12 months of the year is one of the wonderful things about gardening in the Lowcountry.
Anthony Keinath is professor of plant pathology at the Clemson Coastal Research & Education Center in Charleston. His expertise is in diseases of vegetables. He is also an avid gardener. Contact him at email@example.com.