The Lobelia Family includes nearly 400 species of shrubs, perennials and a few are even small trees. There is also one annual, L. erinus, the classic Edging lobelia with its many delicate and pretty hybrid cultivars.
This hardy, semi-trailing groundcover is one of the world’s most popular bedding plants, producing some exquisite brilliant blue and purple shades as well as lilac, mauve, pink , white and many two-toned cultivars. These are unrivaled as a garden edging for the colourful annual or perennial warm-season border.
Edging Lobelias or Border Lobelias are often used in rockeries, window boxes, baskets and as edging to highlight taller plants. These are delicate in appreance but tougher than one might expect.
They are very thin-stemmed creeping, sprawling and trailiing plants with small simple or softly lobed and toothed leaves in light to dark green and sometimes nearly purple or bronze. They thrive in sun or part shade in porous, well draining soils enriched with general plant food and aged cow manure. These Lobelias dislike heavy wet soils, especially in partially shaded sites. most prefer a rather neutral of slightly higher pH.
Seed germinates easily and quickly. Growth is usually rapid provided contidions remain airy, bright and warm. Seedlings transplant easily with little problem. Seedlings are best planted in sheltered spots quite early as final frosts will allow and will often start flowering almost immediately for Spring flowering or in Mid/Late Spring for a Summer and Autumn display
The other members of the Lobelia Family are less well-known and look very different. All are perennials with shallow root systems that demand plenty of moisture and some shading from scalding sun. Many produce showy flower spikes that are good for cutting and dramatically enhance the perennial border.
They are excellent around ponds, streams, bog gardens or grown in pots partially submerged in a pool. Most prefer enriched moist soils with a relatively neutral pH. Foliage produces a small rosetted of leaves which will survive Winter freezing, even in colder climates if well-mulched.
Then in Spring shoots begin to develop which usually attain 1-3ft/30-90cm sometimes more to 1.8m. Dramatic, somewhat orchid-like flowers open up the long stems starting in Summer to Early Autumn. In some species these like L. cardinalis the brilliant red flower spikes are nearly one-sided. In the L. syphilitica species and cultivars the flowers appear all around the stems creating loose cones of flowers.
Once flowering finishes, cut back canes and foliage as the plants die away. Crowns and rootstock are best split every two or three years and can be divided from Late Autumn through to mid Spring. Container-grown plants can be transplanted with care at almost any stage of development. But they do not transplant all that easily when shifted during active growth and flowering. While they were once widely distributed throughout much of North America, they disappeared largely due to their being dug up from the wild while in full flower. Usually these transplants fail to survive the shift.
Yet when transplanted as small semi-dormant rosettes in Early Spring or later in the Autumn and over the Winter months, they transplant easily. But unfortunately, they are much harder to recognise without their flamboyant flowers, which is possibly why they are so less frequently found in the wild today.
The Cardinal Lobelia, L. cardinalis, is a Family member native to lake sides, damp meadows and streams in North America. It thrives in temperate cliimates from the near sub Arctic to the sub tropics. This handsome species produces mostly one-sided, somewhat open spikes to 1.8m/-6ft. that glow with 3-4.5cm scarlet red flowers in Summer.
Dappled shade enhances colour. A similar sometimes larger species with many hybrid cultivars known as Lobelia splendens, comes in cerise, lavender, lilac, amuve, pink, white and red shades. They need constant moisture but more sun. Most lovely Hybrid cultivar, 'Queen Victoria' has highly attractive bronze-red foliage complimenting the vivid velvet red blooms. These are highly attractive to bees, butterflies and Hummingbirds.
Tiny seed of all species are as fine as black dust. Sow these thinly over seed raising mix and barely cover or just lightly water them in. These plants enjoy freely draining positions and failure to germinate is often because the seed has been kept to cold and wet or attempted in heavy, soggy, peaty soils. Usually when started properly these seeds germinate quickly in Spring, especially when started in an airy, very bright and warm position.
The annual species can sometimes throw their first flowers in 6-8 weeks. While the perennial species take several months but will often flower the first year. By the second season they will produce at least one handsome spike. Thereafter they will produce two or three times that number, multiplying each year into tightly packed rosettes.
Lobelia siphilitica, the Giant Blue Lobelia, is actually usually shorter and more stocky than the other spiking species. But the flower spikes are more dense and robust, even though each flower produced is smaller. This lovely species produces hardy, thick spikes in many lovely shades of blue, purple and occasionally white. They create a very pleasing and cooling Late Summer and early Autumn display around water features and are ideal subjects for moist soils in the Blue Garden. Several hybrids cultivars have created orchid and purple spikes.
The most unusual family member is L. tupa from Chile. This 2.5m/8+ft perennial shrub thrives on moist but well drained sandy hills and along the coast. It likes hot, dry Autumns and good drainage. These plants are hardy, spreading or sometimes sprawling shubs. They are easily started from cuttings or seed, but can be difficult to find. Soft, downy leaves support thick, fleshy stems and dramatic 1m/3.3ft red, red-orange or bronze-red flower spikes mostly in Summer and Autumn.
In mild Mediterannean climates they can start flowering in Spring. There they are stunning when planted near Cytisus and Genista species of Golden and yellow-flowering Broom. They make a truly bold and dramatic statement in almost any airy and sunny location when seen on a mature bush.
The Lobelia Family are always well behaved in the garden both on show in pots or in the background. While they may not be the most impressive or showiest member of the garden, they always earn their place and make a fine contribution to nearly any garden design or display
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