The bright and bold: Variegated plants

Coleus ‘Sky Fire’ could light up your patio. — Proven Winners

The quintessential color of the vegetative world is green in a thousand shades, and language reflects this reality — we talk of greenery, green thumbs and the green, green grass of home.

But that’s hardly the whole picture or the whole palette.

While devoted to chlorophyll, the ruling green pigment that’s responsible for photosynthesis, plants exhibit a far wider array of leaf color. Wander through any nursery and you’ll see leaves of silver or gray, yellow, blue, red, purple and nearly black.

These anomalies occur when other pigments in the outer leaf cells mask or replace chlorophyll. Carotenoids, the substance that gives carrots their bright orange color, are responsible for reds, oranges and yellows; anthocyanins produce red-purples, and lutein yields a range of paler yellows and chartreuse.

Some speculate these pigments may shield plants from excessive light, or fend off animal attack. Others believe that plants struggling in the shade of taller brethren — say, tropical species living on the rain forest floor — lean toward colors that help them absorb light in a different part of the spectrum than that used by green plants.

Especially among the tropical species, treated as annuals in our northern gardens, these are plants that have you reaching for your sunglasses. Traditionalists may recoil, but adventurous gardeners can’t get enough. These bold, overstated, attention-grabbing plants are hard to ignore.

Relatively rare in nature, variegated leaves are only found among houseplants and hardy ornamentals because they have been preserved and propagated by human hands. Most often, plant stocks are increased vegetatively, rather than by seed, since variegation is not usually passed along with other traits in the usual way.

Botanically speaking, these plants are known as “chimeras,” after the mystical Greek monster who sported the head of a lion, the body of a wild goat and the tail of a serpent.

Plant chimeras can have as many as five deviant cell layers that override the simple green and are responsible for not only gaudy coloration, but puckered and pleated surfaces that give the leaves of a croton, for instance, their extraordinary appearance. While X-rays, chemicals and certain viruses can produce a variegated appearance, it is most often the sun’s ultraviolet light that stimulates the transformation from Plain Jane to Chiquita Banana.

Variegated plants have traditionally been the province of the plant collector, that individual who can’t resist the maverick and the oddball.

Canna leaf - who needs flowers? — HorsePunchKid/Creative Commons

Trends do tend to have their cycles, and with at least three of the most sought-after tropicals, there is a remembrance of things past. The Victorians, who witnessed the first great wave of unusual and exotic plant introductions, were in love with bizarre forms, colors and shapes in their ornamentals.

Not surprisingly, one of their favorites was coleus, a native of Indonesia and Africa also known as painted nettle. The Victorians doted on these colorful plants, using them in bedding schemes, growing them in conservatories and flaunting them in ornamental urns. Back in the “70s, they enjoyed a revival, and rare was the plant-minded individual who didn’t have at least one potted specimen on the windowsill.

Their ease of culture and propagation — cuttings will root in water in 5 to 7 days — made them ripe for amateur enthusiasts and easy to trade around. But they fell out of favor until recently, when new cultivars from Asia worked their way into the market with colors, textures and leaf shapes never before seen.

The croton is another plant making a comeback. Its leaves emerge as green, but mature into a pigment-splashed cacophony of blood red, sunset orange, chartreuse, white and gold on a leathery, puckered canvas. This Malaysian plant is loud, no doubt about it, with a palette that would put Gauguin to shame.

Crotons were last popular in the 1920s and ‘30s, when Miami was the croton capital of the world, but 50 years later were hard to find. Their revival can also be attributed to new blood — in this case, new species from Thailand that sported even brighter color on smaller plants, ideal for container culture. Bearing names like ‘Stoplight,’ ‘Gloriosa’ and ‘Bravo,’ new hybrids are flooding the market.

Another big player in the color explosion is the canna, formerly consigned to public plantings around municipal buildings and street plazas in the South, where their towering forms loomed as much as 10 feet overhead. New, more dwarf varieties brought these plants down to a size that makes them suitable for home gardens, and hybridizers went to work to give the broad, supersized leaves as much — or more — eye-appeal as the bright, lily-like flowers.

Now you can have ‘Pretoria,’ the Bengal Tiger canna, whose orange blossoms are offset by leaves boldly striped in bands of yellow and green, or ‘Durban,’ sporting purple leaves with red veins and scarlet flowers. Or ‘Tropicana,’ a wild one whose leaves emerge an intense purple, but become striped in green, yellow, pink and red — with vivid orange flowers on top like the cherry on a sundae.

None of these grow much more than six feet, and some are a petite four feet. Cannas turn out to be more versatile than you might think, and since they are water-loving, can be incorporated into a water garden or planted beside a back-yard pond.

Variegated plants can sometimes throw off shoots that revert to solid green. These should be removed immediately, since they are more vigorous and can take over from the less stable variegated parent. If you leave green shoots in place, you may wonder where the color went as your plant undergoes an identity change.

Variegated plants and their bright-foliage cousins will never take over the garden world, but add that certain spice of variety to the otherwise tame green of our domestic landscapes. Sure, they make you gasp and bring you up short. But if your garden is in danger of being too staid, too square, or too predictable, go for the color gusto. Why? Because you can.