Before all our minutes are swallowed by the holidays, and while there’s still space in the greenhouse—pending the onslaught of spring seedlings—let’s consider a special winter bonus for greenhouse-owning gardeners—the privelege of enjoying winter-blooming plants! All the plants suggested below will thrive in bright sun and cool temperatures—ideally between 40 and 50 degrees. Remember that cooler temps encourage healthy, stocky plant growth, and also discourage the growth of pest populations.
Anisodontea x hypomadara, or “African Mallow” is perpetually covered with cheerful rosy pink mallowlike flowers, and is well-suited for standards.
The fragrant flowers of many cestrum species have made them valuable conservatory plants since Victorian times. Cestrum nocturnum, is also known as “Night Jessamine” due to its intoxicating evening perfume. Other cestrum are prized for their visually attractive flowers—Cestrum‘Smithii’ has clear pink ones.
Heliotrope makes an ideal greenhouse subject, with flowers that range in color from white to deepest purple; they exude a wide variety of scents as well, from vanilla to baby powder. Heliotropium ‘Alba’ may have the strongest vanilla scent. The flowers of Heliotropium ‘Iowa’ certainly are the deepest violet shade, and have a fragrance both lovely and complex.
Most “Jasmine” are grown for their pungently sweet-scented blooms. Jasminum polyanthum is covered by midwinter with small, waxy white flowers emitting that unmistakable perfume. Jasminum officinale ‘Fiona Sunrise’ adds handsome golden foliage to the allure of its fragrant white blooms.
Michelia figo, also known as the “Banana Shrub,” is actually a member of the magnolia family, a fact hinted at by its shiny leaves and fascinating cream flowers tinged with purple. The common name refers to the truly banana-like fragrance of its flowers.
Osmanthus fragrans is one of my favorites, and its period of bloom is ideal for the winter greenhouse. Both leaves and flowers are not particularly noteworthy in their appearance, but the exquisite fragrance of the small, creamy white flowers is outstanding.
Plumbago was a popular resident of Victorian conservatories, and should be in yours too; its powder blue phlox-like flowers are nearly continuous. Plumbago auriculata ‘Powder Blue,’ a recently selected form, has exceptional vigor and startling ice blue flowers.
When the hustle and bustle of the next month seems overwhelming, step for a moment into the greenhouse and take a breath. That wonderful perfume, with its promise of verdant growth, might just carry you through the darkest season until we all can garden outdoors again.
For more plants that bloom during the winter, as well as detailed information about how to grow them, see Alice’s book, “Bulbs in the Basement, Geraniums on the Windowsill,” and her website, alicemcgowan.com.