Blue flowers are appropriate for the summer because of the cooling ambiance they provide.
Speaking of which, are you familiar with blue lace, also known as throatwort (Trachelium caeruleum)? If not, perhaps you should be. In the Armstrong Nurseries plant catalog from 1936, it reads: “Many enjoy it more than any other plant in their garden … In late summer it produces great spreading panicles of bright blue flowers which keep for days in the house after cutting.”
Recently, at the entrance to the Jerusalem Botanical Gardens, I saw a mass planting of blue lace. Generous clusters of flowers in lavender-blue, violet and purple riveted my attention. Growing in clumps to a height and girth of three feet, there really is no late summer bloomer in its class. Flower clusters are four to eight inches wide yet somehow lacy. Added bonuses are its attractiveness to birds (at xeraplants.com it’s described as “hummingbird manna”) and butterflies, resistance to pests and diseases, and its longevity in dry flower arrangements. Flowers also carry a sweet fragrance and, if religiously deadheaded once they begin to fade, new blooms will keep coming into October. This plant is not too often seen in the nursery trade but it is grown by San Marcos Growers (smgrowers.com) so you should be able to special order it from one of the nurseries they supply.
The botanical name of Trachelium is based on trachelos, the Greek word for neck, and references the plant’s reputation as a sore throat remedy. Although with throatwort, the lavender to purple color spectrum is most commonly encountered, white, green, pink, and red cultivars are also available, although not as sturdy as the familiar type. To emphasize ithroatwort’s affinity with the color blue, the species name of caeruleum is derived from Latin words meaning “blue” and “sky.” Incidentally, the -wort suffix in throatwort is seen in the common names of many plants. It is an Old English word for plant or root and invariably refers to a species with vaunted medicinal qualities. Take note that you will probably need to water throatwort more often than typical garden fare.
While throatworts are evergreen, they need to be cut back nearly to ground level at winter’s end to revitalize themselves. Expect them to last for three to five years but there is a good chance, in the meantime, that they will self-sow if the soil around them drains well. You can also propagate from 4-6 inch cuttings by dipping cutting ends in root hormone before insertion into a 50:50 peat moss and perlite mix. Preserve humidity by covering the propagation pot with a humidity dome (bottom of a large plastic soda bottle will do) or large sandwich bag. Throatwort is a fine candidate for container growing both outdoors and indoors as long as it receives most of the day’s sun. Grown indoors, it would benefit from the presence of a humidifier. Enter “humidifer for plants” in an online search; recommended models for single rooms cost between $45 and $75.
Several other species that are members of Trachelium’s plant family — the bellflower family (Campanulaceae) — are noteworthy garden selections. The Campanula genus is the flagship genus of this family. The word campanula is derived from “campagna,” meaning little bell. (You may recall the campanile or bell tower on your college campus.) No one I know has ever failed to be charmed by the bellflowers seen on Campanula species. Several hundred species exist yet only a few are locally encountered. However, a greater variety of these long-blooming, carefree plants is sure to be seen in the not-too-distant future as advances in propagation and hybridization techniques offer an increasing array of bellflower selections.
Bellflowers are meant for viewing close-ups. Bellflower beauty is always whispered, never shouted. Serbian bellflower (Campanula Poscharskyana) is the most recognizable member of the bellflower group. It is a popular ground cover with flowers that are typically lavender-blue although Alba, a white cultivar, is occasionally seen. “Tranquil” is a fitting adjective for describing Serbian bellflower due to its soft, heart-shaped foliage, conveying a “touch me” message.
Serbian bellflower is well-suited to containers and hanging baskets because of its trailing growth habit and prolific flowers throughout the spring and most of the summer. It is a reasonably drought-tolerant selection that you can use as a filler in semi-shade exposures around impatiens, begonias and ferns. Campanula grows rampantly at times but its roots are shallow, making it easy to control.
A common mistake is to use Serbian bellflower as the only plant in an area more than a hundred square feet in size. When planted over a large expanse, Serbian bellflower becomes invisible. It needs to be seen up close, in small to medium-sized flower beds next to an entry, along a walkway, adjacent to steps or in pots, to be appreciated. It demands sun protection as much as any other ground cover, yet eschews deep shade, and blooms well as long as it gets a few daily hours of good ambient light.
The plant with the most imposing bellflowers is known as Canterbury bells (Campanula Medium). Its chalice-shaped blooms are 2 inches long and nearly as wide. Canterbury bells is a plant that, when you first lay eyes on it, you will wonder about its origins: Is it part of the plant kingdom or did it come from the artificial flower shop? It is the ideal plant for stimulating horticultural interest among children and other potential gardeners. Unfortunately, you will rarely, if ever, see Canterbury bells at the nursery, but it’s readily available in seeds. Give it half-day sun to partial-shade exposure.
Another noteworthy blue flowering plant in the bellflower family is Lobelia, even if its blooms look more like tiny birds or butterflies more than bells. Everybody loves lobelia. How can you resist it? Lobelia (lobelia erinus) is a lovely botanical wonder that grows into a tidy globe around eight inches in size. It does well in mixed flower beds or as an edging plant in perennial borders.
One of lobelia’s virtues is its slow growth rate, making it one of the best plants for container growing. The petunia, for example, whose brilliant red, pink, blue and purple colors give it a unique presence, simply grows too fast to be of lasting value in a flowerpot or garden bed. Yes, you can – and really must – cut petunias back after three or four weeks of growth, but even then they will only grow for another month or so before becoming leggy beyond redemption. Lobelia, by contrast, will hold up well for at least four months, and its good looks may persist for six months or beyond, depending on the weather. If it should stop flowering, cut it back by half and wait for rebloom.
Two notes of caution are in order regarding lobelia. First, it needs sun protection as temperatures warm; second, it requires above-average soil moisture. By planting it in partial sun, you can extend the life of lobelia in the summer garden. Although lobelia is most well-known for its dark, marine blue varieties, it is also available in light blue, violet, white and carmine.
An additional member of the bellflower family, not to be forgotten, is the balloon flower (Platycodon grandiflorus), a perennial whose silky mauve-blue flower buds look like expanding balloons as they enlarge. Eventually, the buds open into pentagram-shaped flowers. Like the other blue plants mentioned above, the balloon flower is cold hardy and combines well with lobelia and throatwort in an all-blue flower bed.
Other blue bloomers you might want to try would include Veronica species, with dense arrays of blue flower spires; Geranium ‘Johnson Blue’ and other true geranium cultivars, whose flowers and foliage are more delicate and understated than the coarser and flashier ivy and zonal geraniums; bluebeard (Caryopteris incana), whose ethereal blue inflorescences surround the stem; butterfly flower (Clerodendron ugadense), so-named because of its flowers’ exact resemblance to porcelain blue butterflies, antennae included; and ‘Blue Fortune’ giant hyssop (Agastache), with robust flower spikes reaching nearly a foot in length.
Regarding these or any other flowering plants, there is one rule that cannot be repeated often enough: Plant in well-composted soil. Plants look good in nurseries because they have been fertilized since birth. When you place them in your garden or in containers, plants used to a steady mineral feed may go into a funk if the minerals they need are not immediately available to them. If you lack a rich compost, it is advised to add a slow-release fertilizer to maximize flowering. Apply it topically so that, when it is exhausted and disappears, you will know it’s time to add some more.
I mentioned in a previous column that I could not find a source for California sea lavender (Limonium californicum) but have been gratefully informed by several readers that this plant is available at both the Theodore Payne Foundation (theodorepayne.org) in Sun Valley and the Tree of Life Nursery (californianativeplants.com) in San Juan Capistrano.
A week from today, on August 24th, from 9 a.m. to 5 p.m., The American Begonia Society is holding a convention at the Staybridge Suites & Holiday Inn, 2680 & 2640 N Lakewood Blvd., Long Beach.
Candace Nakanishi, Orange County Begonia Society Secretary, describes the event as follows: “There will be a show and sale featuring hundreds of Begonias of unique types and forms which grow well in our climate. There will also be terrariums with tropical and subtropical Begonias as well.”
On Aug. 24th and 25th, from 10:30 am until 4 p.m., there will be a Hibiscus and Plumeria show at Sherman Library & Gardens, located at 2647 E. Coast Hwy., Corona del Mar (thesherman.org). Expert talks and demonstrations will be presented courtesy of the California Hibiscus Society and the South Coast Plumeria Society. Admission is $5.
California native of the week: Many Artemisias are native to California and our most prominent member of the genus is California sagebrush (Artemisia californica). It is generally short in stature but may grow up to five feet tall while its ‘Canyon Gray’ cultivar hugs the earth and California sandhill sage (Artemisia pynocephala) is a compact subshrub whose ‘David’s Choice’ cultivar grows only a foot tall. California mugwort (Artemisia douglasiana) is not as well-known as the above species but it should be. The California Native Plant Society (cnps.org) extols its foliage as follows: “When rubbed on the skin, the leaves have a natural moisturizing effect and are said to counteract the oils of poison oak if applied immediately, which is handy since they are often found growing near one another.”
Do you have any plants with blue, violet, or purple flowers to recommend? If so, send your experience growing them to [email protected]. Your questions and comments, as well as gardening predicaments and successes are always welcome.
