Lobelias for Your Landscape

Late summer is probably not the most exciting time to hike through our native woodlands. Weekend rambles present varying shades and textures of green. It’s pleasant, but not engaging. A cool breeze may flutter a yellow leaf or two to the ground, a mere portent of the colorful autumn-kissed leaves to come. Then suddenly, across the greenness, a brilliant scarlet spike appears. It’s nearly luminous – it’s lobelia!

Specifically, it’s cardinal flower, Lobelia cardinalis, named, like the songbird, after the bright red vestments of the clergy. And surely, in all nature’s palette, no other wildflower can compare with the sheer intensity of its fire-engine red color. Even in the deepest shadows of a quiet marsh, the chest-high racemes of its flowers flash out like beacons across many hundreds of feet.

Cardinal flower is all the more remarkable as red is seldom found among our flowering native plants. Yellow, white, pink and purple: sure -- but seldom red, save for the odd bee balm. And when added to the lackluster canvas of a waning summer, you’ve got a bona fide phenomenon.

Botanically, cardinal flower is an herbaceous perennial, best suited to moist areas like stream banks and wetlands, as well as moist woodlands and meadows. The plant and its cultivars can also thrive in a garden setting, even in full sun, although the soil must be kept evenly moist. Applying a layer of mulch can help, although it might be best to select a site with filtered light. Cardinal flower can easily survive flooding and the soggiest of yards, but it will not tolerate drought or excessive heat.

There are some important cultural notes to consider when growing cardinal flower. For one, the plant, while long-blooming (until frost) and perennial, is unfortunately somewhat short-lived, lasting roughly three years. However, the plant readily self-sows, and will produce a substantial number of seedlings year after year to keep the lobelia colony growing. Two-celled seed capsules are formed in mid to late autumn, split open and scatter numerous tiny seeds upon the ground. Those seeds will sprout in spring, although they do require exposure to light. Therefore a heavy layer of mulch might prevent reseeding.

More importantly, mulching might smother the basal rosette of leaves that hug the ground in winter, after the central stem has died back. That might hinder growth early in the year, or even cause crown rot and the death of the plant.

Cardinal flowers can also be propagated by dividing large established clumps, or by separating basal offshoots from the mother plant in fall, after the flowers have faded. And much as you cannot have red states without blue states, our scarlet-blooming cardinal flower is complemented by a twin species: great blue lobelia (L. siphilitica).

Both lobelias share a wealth of splendid features, such as easy propagation and care, and both bring a burst of color into the natural landscape when it is most appreciated. However, to its credit, great blue lobelia is generally more forgiving of moisture and heat conditions, and even more flexible in garden uses.

The flowers of both plants feature long tubular florets uniquely adapted to pollination by hummingbird. The relationship is especially symbiotic as the ruby-throated hummingbird is significantly dependent on the nectar from these late flowering plants to keep them “fueled” during their migration south. The flowers are also popular nectar sources for the spicebush, pipevine, and black swallowtail butterfly.

Our lobelias have also played an important medicinal role among Native Americans, who used different portions of the plants, from leaves and seeds to mashed roots and stems, to create poultices and infusions to treat headaches, nosebleeds, typhoid, respiratory ailments, common colds, and even as a culinary preventative for divorce. In fact, the botanical name of blue lobelia is derived from its use in treating venereal disease.

Of course, our lobelia cousins have been subject to hybridization over the years, and there are a number of truly striking cultivars available, often referenced as Lobelia x speciosa, including one of the most popular hybrids: ‘Queen Victoria’ with scarlet flower spikes up to three feet tall rising above bronze foliage. ‘Bee’s Flame’ offers bright red flowers and purple foliage, as does ‘Dark Crusader.’ ‘Russian Princess’ is another very popular selection with magenta flowers and maroon foliage. ‘Alba,’ naturally, is a white-flowering cultivar, while ‘Twilight Zone' and ‘Heather Pink’ have soft pink flowers, and 'Angel Song' is a blend of muted creamy salmon.

Beyond our two native subjects, there are almost another 360 species of lobelia found worldwide, including several popular garden favorites. Chief among these is Lobelia erinus, commonly called edging lobelia, which comes in two useful forms, both attractive to butterflies and profusely covered with small, intensely colored flowers in midnight blue, purple, violet, scarlet, rose, pink or white, often with bronze or greenish-bronze foliage. A fast-growing trailing variety features long, sprawling stems covered with half-inch wide flowers which gracefully cascade over the sides of hanging baskets and window boxes, or add a touch of casual elegance to formal container plantings.

The compact, bedding variety is forms dense, brilliant mounds about six-inches tall, ideally suited for use as a ground cover, an edging plant along sunny or partially-shaded pathways, tucked into rock gardens, or artfully blended together in lush masses of mixed colors. Blur your vision while looking at such a planting and you’ll think you’ve slipped into a Monet canvas! Most garden centers carry a large selection of flats in spring, including such varieties as ‘Paper Moon,’ ‘Monsoon,’ ‘Rapid Blue,’’ Crystal Palace,’ ‘Lilac Dream’ and 'Horizon Light Pink.'

Whether red or blue, native, hybridized, or introduced, there is surely a lobelia (or five or six) that would make a welcome addition to your landscape. And if you go native, remember that you’ll also soon welcome those ruby-throated hummers, and the fluttering color of butterflies.

Copyright 2009, Joseph M. Keyser

Natural Color for Shady Landscapes

One of the most daunting challenges facing the average gardener is planting in full shade. Not the partially sunny, light-dappled kind of shade that feels so lovely in midsummer, but the deep Amazonian shade so dark that moss will grow on your garden trowel if you don’t keep moving. Not surprisingly, many folks facing full shade simply give up and resign themselves to a dull landscape of invasive ivy and much over-utilized liriope, little realizing that there are ways to foster splashes of vibrant color even in their horticultural twilight zone.

One possible approach is to treat a fully shaded yard more like a natural woodland area, selecting a variety of native plants which are generally well-suited to low light conditions.

You might start by seeing whether your landscape can use some small trees and shrubs. For example, while many yards are full of tall, mature trees, such as oaks, hickory, and poplars, there is usually little else growing between the sky-high canopy and the ground below. Filling that space, the “understory,” is the first best place to begin adding color.

Some suggested specimens include Shadbush, which provides white flowers in spring and brilliant foliage in autumn, and Redbud, which also features pinkish-purple spring flowers and red leaves in fall.

Fringe tree is one of the true delights of our local woodlands with extremely fragrant, pendulous clusters of bright white flowers, as is Sweetbay Magnolia, with large aromatic white flowers and brilliant red berries.

Virginia Sweetspire produces long, fluffy racemes of fragrant white flowers in summer, followed by wine-red foliage through autumn and early winter.

And finally, round out these aromatic offerings with Sweet Pepperbush (Summersweet), with its tempting midsummer display of apple-pie scented, pinkish-white flower spikes, usually heavily-visited by butterflies, and an encore of yellow foliage in fall.

Beneath the understory, you will want to introduce a full array of woodland wildflowers, which can expand or reflect the key elements of this region’s natural habitat. Be sure to keep succession bloom in mind as you select your plants. For example, a great many woodland plants will put on a fine show in early through mid-spring but these “ephemerals” will soon fade, leaving you with foliage and fond memories.

That is not to say that you should not include spring ephemerals, which are often among the most spectacular plants around, such as Virginia Bluebells, which explode in April yet sadly fade in May. But think in terms of plants which will flower at different periods throughout the year, and which can do double or triple duty with autumnal color and/or colorful fruits and berries.

Some native selections, such as Great Blue Lobelia and Columbine, also readily attract butterflies and hummingbirds, which is yet another way to introduce color into your garden – and into your life!

Great Blue Lobelia should also be greatly valued for its brilliant bluish-purple tubular flowers. These appear on one-to-three foot long spikes which bloom from August through October. The species is cousin to the showier Cardinal Flower, but performs far better in partial to full shade. Moreover, the spikes also make for excellent cut flowers, if you can bear the thought of removing them from your garden.

Our native Columbine is favored for its nodding, bell-shaped flowers with tubular red petals or “spurs” and yellow center or “lips” which appear through April and May. The foliage provides a variety of color as it changes during the year from green to shades of maroon. It also reseeds easily, helping it to fill in spaces like a ground cover. Note that in addition to the native species, there are cultivars available which can offer extended blooming periods and exquisite color combinations, such as creamy white flowers with golden centers.

Dutchman's Breeches is another ephemeral native with small, fanciful white and yellow flowers on arching stems or “scapes” and delicate, fine-cut light green foliage. Unfortunately, the flowers only appear from early to mid spring. On the other hand, a close relative, Wild Bleeding Heart, provides the same light touch with wispy mounds of seemingly etched foliage, but with delicate rosy-pink, sometimes purplish, heart-shaped flowers that last from mid-spring through fall.

Alumroot (Heuchera) provides year-round interest with semi-evergreen ruffled leaves which often appear silvery-white with a network of green veins. Some plants also show splotches of reddish-purple, which will spread across the leaf surface and turn progressively darker as summer creeps towards cooler weather. Slender stems or panicles with small bell-shaped flowers appear from April through June. Alumroot makes an excellent ground cover or edging plant if established in thick masses. And look for some of the popular cultivars, like ‘Coral Bells’ which features much darker green leaves, bright, almost reflective silver highlights, and deep red veins.

Foam Flower is another excellent ground cover which spreads readily through underground rhizomes and seeds. Like Alumroot, it is also semi-evergreen, with green foliage that turns maroon as the weather gets nippy. White flower spikes appear from early spring through midsummer, although hybrid varieties, such as ‘Spring Symphony,’ develop spikes of flowers in a pastel pink, almost 18 inches tall, which will last from summer through fall.

For a bit more height in your understory, consider planting several masses of the native aster, with several species readily available which will produce dense clusters of snowflake-like flowers on two-to-three foot upright stems starting in late summer and lasting until close to November. White Wood Aster produces a cloud of butterfly-friendly flowers with very small white petals and a yellow centers which will gradually turn reddish-purple.

Blue Wood Aster has even showier flowers ranging from pale blue to violet, and have inner pale yellow disk florets which turn reddish-purple as the flower matures over several months. Both White and Blue Wood Asters naturalize (spread) rapidly in the garden using both seeds and rhizomes.

And because no woodland is complete without ferns, consider adding ferns to fill in empty spaces and provide some interesting texture or structure against which your other wildflowers can shine. Christmas Fern will provide evergreen, leathery fronds, while New York Fern offers both a more delicate array of pale green fronds, and it will also spread rapidly, closing ranks with your other ground covers.

Copyright 2009, Joseph M. Keyser