Growing Purple Basil

Last year, I fell in love with purple-leaved basils and could think of little else all summer. My ­season of obsession ended with a garden of nearly a dozen varieties, from the petite New Guinea with its arrow-shaped leaves to the voluptuous, ruffled foliage of the massive Italian Genovese Grande Violetto.

If you see green when you think basil, it’s time to take another look. The purple varieties shimmer with tender iridescence, and when the light is right and soil conditions have been just so, you can see highlights in the leaves that might seem purple or red or blue or maroon or violet or burgundy, or even green. These are the kinds of rare, joyful subtleties that startle the eye when viewing the impressionist canvases of Cézanne, but they can happen every day in the herb garden.

Whatever color you see in these basils, they have the same range of spicy anise scent and flavor, and the same uses, as green varieties: in fresh-picked salads, with fruits and cheeses, as garnishes, even in purple pesto if color-rich food is your pleasure. If you’ve a mind to be experimental, you can create a sinfully unusual treat by adding liquefied purple basil leaves to crème fraîche. Need I mention that purple basils excel in their traditional use for flavor and color in herb vinegar? Just ­because they aren’t green doesn’t mean that purple-leaved basils skimp on flavor; research conducted by Dr. James E. Simon at Purdue University in 1986 showed that the leaves of Dark Opal basil produced more ­fragrance- and ­flavor-producing essential oil than ­fourteen of the ­fifteen other basils tested.

Purple basils, like green ones, have the typical four-sided stems of the mint family, Lamiaceae (Labiatae), and carry their flowers in whorls of six blossoms each on spikes of varying length. Blooms begin opening at the base of the spike and work their way to the top. And purple basils have wild, flirtatious genes that give rise to many varietal changes. Botanists with a sense of humor like to lift an eyebrow and explain, with a twinkle in their eye, that basil varieties are “promiscuous” and cross among themselves and with other Ocimum species with abandon–a charming but frustrating trait. This lack of fidelity complicates our untangling of the lineage of the many offspring created by basil garden parties, but it also gives rise to an interesting collection of stories about how these basils have come to be, with and without the intervention of botanists, horticulturists, and growers like myself.

Ocimum basilicum ‘Purpurascens

The granddaddy of purple-leaved garden basils may well be Ocimum basilicum ‘Purpurascens’, first identified in the 1830s by George Bentham, a British botanist. What is striking about this bushy, 2-foot-high basil is that as many as four pairs of leaves at the top of each stem are dark purple while the leaves lower on the stems shade to a pure, even light green. All the leaves are egg-shaped (about 11/4 inches wide and 2 inches long) and sparsely toothed along their margins. Whorls of small, light lavender to light purple blossoms are carried on 3-inch-long dark violet stalks, and the scalelike bracts at the flowers’ base and the calyces which encircle the corollas are both dark purple. The leaves, when brushed, release a pleasant anise scent.

O. b. ‘Purpurascens’ came to me in that haphazard, unexpected way in which nature presents its variants to gardeners: it popped up unexpectedly in a flat of otherwise green Greek basil seedlings, and at almost the same time in a flat of Thai basil–just as I was beginning research for this article. I should say that these two surprise guests looked like O. b. ‘Purpurascens’ in most regards, though they turned out to have slightly different flower colors and one possessed branched flower spikes.

Much of what is sold in this country as O. b. ‘Purpurascens’ probably is not: the word “purpurascens” has become a handy, if incorrect, all-purpose tag for almost any purple-leaved basil.

A seemingly close relative of O. b. ‘Purpurascens’ is O. b. ‘Thyrsiflora’, which I have yet to see for myself and which may not be available in commerce. It has a branching habit that forms a plant somewhat like an upside-down pyramid; the flower stems are short and branched, and the flower whorls are so close together that they appear to be spirals.

Dark Opal Basil

With its depth of color and subtle iridescence, O. b. ‘Dark Opal’ is ­indeed gemlike, though more than thirty years after its introduction, its developer, John Scarchuk, told me he couldn’t recall any particular reason why he chose that name for the plant he selected and nursed into commerce. Dark Opal is probably the best-known purple-leaved basil sold today, and many cooks prefer it over other purple varieties for its flavor. It is sometimes incorrectly offered as O. b. ‘Purpurascens’.

There is excitement and romance in the story of how Dark Opal came into being. In the mid-1950s, U.S. Department of Agriculture plant explorers harvested wild basil seeds in Turkey, and Scarchuk, a young instructor just beginning his career at the University of Connecticut, was lucky enough to receive some of them. Working at the university’s Storrs Agricultural Experiment Station, he planted the seeds, and up came what he later termed “a mixed batch” of plants. Scarchuk and his partner, the late Joseph Lent, selected a dark-purple-leaved basil with toothed leaf margins; then they spent several years crossing it with itself until they achieved the uniformity they desired. Dark Opal basil was an All-America Selection winner in 1962, the first of seven such awards Professor Scarchuk was to receive for his breeding work during his thirty-eight years at the University of Connecticut.

The Ferry-Morse Seed Company, which first brought Dark Opal to the marketplace, devoted an entire page in its 1962 garden catalog to announcing the new cultivar, and the prose was as purple as the plant. “It’s a flower! It’s an ornamental foliage plant! It’s an herb!” the catalog exclaimed. “You are looking at a plant never before seen in any American garden. The foliage has the deep, almost-black purple of a purple plum. Over it, a bronzy-green sheen, iridescent, changes each time a breeze moves the leaves.” All this and “little spires” that “are sprinkled with delicate lavender blossoms.”

I do not see lavender when I look a Dark Opal in the blossom; in the best of them I see deep fuchsia blossoms with black-purple bracts on a reddish purple stem. (A packet of Dark Opal seed today will provide a variety of flower color: everything from that described above to a light lavender, almost white flower.) Dark Opal holds a unique place in the history of cultivated basils in the United States because its influence goes far beyond its awards; it lit the imaginations of many breeders who subsequently used the plant to develop other purple-leaved basils.

Rubin Basil

One of Dark Opal’s direct and most recent descendants is O. b. ‘Rubin’, which made its North American debut in 1993 in the mail-order catalog of Richters, the noted Canadian herb seed and plant specialist. This basil is a “reselection” of Dark Opal made by a European firm, according to Conrad Richter, the son of the company’s late founder, Otto Richter. Rubin was intended to provide gardeners with more uniform plants from seed than may be obtained from Dark Opal today. “Rubin,” Richter says, “still is not a dark, dark purple . . . . There’s some fading, but you don’t get streaked leaves. It’s a step in the right direction.” Rubin closely resembles Dark Opal, and whether it merits a completely new name may be a matter for debate among taxonomic nitpickers, but one commercial grower I interviewed lauded Rubin as “more uniform, vigorous, and disease tolerant” than the plants produced by the current Dark Opal seed. (The uniformity of Dark Opal seed has declined in recent years. Professor Scarchuk said he had noticed the problem and thought it could be rectified with improved production techniques, but improvement may be more elusive than that. At least one seed merchant advertised last year that he had an “improved” seed lot that eliminated much of the variation; I questioned this claim after looking over several thousand seedlings.)

Purple Ruffles Basil

O. b. ‘Purple Ruffles’ grew from a large herb breeding program begun for W. Atlee Burpee and Company in the late 1970s by the late Ted Torrey. In a reminiscence at the 1989 conference of the International Herb Growers and Marketers Association, Torrey recalled how he had noticed the variability of many herbs grown from seed soon after he went to work for Burpee in 1947; thirty years later he was able to put to work his knowledge of this genetic delinquency, introducing a number of important new herb varieties. Torrey created Purple Ruffles in 1980 by crossing Green Ruffles (another of his creations) with Dark Opal. By 1984, the variety had been “fixed”, and it was entered in the All-America Selections. This was, as Torrey recalled, “the shortest breeding project in my over forty years with Burpee.” The delay until 1987 for the introduction of Purple Ruffles occurred because of the need to produce the quantity of seed to meet anticipated commercial demand.

Purple Ruffles is a robust basil with large, savoyed leaves; it may grow 2 feet high and act as a significant accent in the garden, especially when paired with green or silver herbs. Its flowers are light lavender with a dark fuchsia throat. Purple Ruffles lacks the more assertive anise fragrance of Dark Opal. In recent years, the quality of Purple Ruffles seeds has declined to the point that in 1993 herb plant producers complained that Purple Ruffles had gone the way of Dark Opal and the seed line was headed toward extinction.

Two basils that resemble Purple Ruffles are sold in Italy and are sometimes available in the United States. I first imported O. b. ‘Genovese Grande Violetto’ in the late 1970s, well before the introduction of Purple Ruffles, but I have been unable to track down the story of its development; all appeals to my seed source in Italy for details have gone unanswered. The plant has large, heavy, ruffled leaves that are decidedly purple but have a red undertone when light shines through them; the leaves are so heavy that the weight of the ­foliage sometimes causes the stems to split. While the seed does produce some variants, it produces far more plants true to type than does that of Purple Ruffles. Seedlings of Genovese Grande Violetto appear to be quite susceptible to damping-off and root rot.

Nichols Garden Nursery in 1993 offered imported seed of a variety called Italian Red basil that was similar but came from a different Italian source from mine; seed for this variety is in short supply for 1994, according to the nursery’s owner, Rose Marie Nichols McGee. The background of this basil is also unknown.

African Blue Basil

Dark Opal’s genes also appear to be an influence in another purple basil variety. Peter Borchard of Companion Plants in Athens, Ohio, feels certain that African Blue basil (O. ‘African Blue’) is a natural cross between O. b. ‘Dark Opal’ and O. kilimandscharicum, the African camphor basil that can grow 5 feet high and is named after Mount Kilimanjaro. The two basils grew in adjoining beds in Borchard’s seed production area, and in 1983, Borchard spotted a curious, blue-veined seedling growing in one of the beds. He potted it up to see what would happen, and named the resulting plant African Blue. By 1985, the basil was in Companion Plants’ mail-order catalog. Such hybrids are generally propagated by rooting stem tip cuttings and sold as plants only. Propagation by cuttings preserves the characteristics of the original seedling, which isn’t true with seed propagation.

African Blue basil is a large, bushy, energetic plant that produces profuse lavender blossoms arranged on 6-inch-long purple-blushed stalks. The leaves are egg-shaped and pointed with a slightly serrated edge; new leaf growth is often heavily brushed with purple, which fades in time to green on top with purple veining. Leaf undersides are more heavily colored with a reddish purple, and the stems are suffused with violet. Plants grow 3 feet or more high and as wide in a season and create a splendid effect in the garden. Their aroma is quiet, a bit camphorated, and at times hits you with a whiff of fresh bologna sandwich–or is that my imagination? Although I have seen recipes recommending use of the leaves, African Blue basil is primarily ornamental for me.

Purple Bush Basil

Dark Opal played an important role in the creation of O. b. ‘Well-Sweep Miniature Purple’ by Cyrus Hyde of Well-Sweep Herb Farm in Port Murray, New Jersey. Hyde remembers reading an article in the early 1970s in The Herb Grower by Gertrude B. Foster, an author and herb pioneer who has had a major role in the modern popularity of herbs in the United States. The article mentioned that Mrs. Foster grew a small-leaved purple basil on her farm near Morristown, New Jersey, in the 1940s; Mrs. Foster and her husband, Philip, produced herb seeds for many American seed companies and had an extensive selection of rare and unusual plants.

Thirty years later, Hyde could find no one who had the Fosters’ purple bush basil or seeds from it. As luck would have it, a customer came to Well-Sweep one day with a plant he wanted to share with Hyde: a compact green basil from Armenia with a rounded shape and small, pointed leaves. Hyde saw the possibilities and crossed the Armenian basil with Dark Opal and got a few small-leaved purple basil plants from the resulting seed. Hyde told me he spent several years breeding these dwarf purple basils with themselves, trying to improve the variety and stabilize it, but he was dissatisfied with the results. He heard of a purple basil in the collection of Helen Darrah, author of a monograph titled The Cultivated Basils, that he thought might help, but when he grew it, only the flower bracts were purple; the leaves were green. “I figured it carried the purple gene because it had purple bracts,” Hyde recalled recently, and he crossed the green basil that had purple bracts with his dwarf purple plants. This last cross satisfied him, but the seed line remained unstable. “From seed you’ll get everything,” he explained, and his purple bush basil must be propagated from cuttings.

Well-Sweep Miniature Purple, which exudes a sweet, spicy scent, is a striking annual shrublet about a foot high with pink flowers. Cuttings, when pinched back several times, mature into rounded plants with leaves that are pointed and about 1/2 inch wide and 3/4 inch long; older leaves lower on the plant tend to be green suffused with purple while leaves farther up the stems are dark purple; the undersides of all leaves are reddish purple.

The plant possesses a colorful, soft charm in the landscape. In 1983, the U.S. Arboretum in Washington, D.C., through its National Herb Garden, gave Hyde’s creation a rare honor by distributing it to herb growers and nurseries in the United States. (The plant was identified at the time as O. b. ‘Minimum purpurascens’, and Hyde was not credited as the developer.) This delightful little basil is rarely seen in mail-order plant catalogs today (probably because of growers’ unwillingness to propagate an annual herb from cuttings), and a decade after the plant was distributed, it is no longer in the collection of the National Herb Garden.

Holly’s Painted Basil

O. b. ‘Holly’s Painted’ was introduced in 1993 and is one of my own selections from a group of Purple Ruffles variants; the name honors Holly Shimizu, now of the U.S. Botanic Garden, who has done so much during her career to popularize herbs. I spent several years selecting variants from Purple Ruffles until I found one that would keep its color through the winter; one of the least charming characteristics of most bicolored variants I have handled is that they tend to revert to solid green after being carried over the winter in the greenhouse.

The light green ruffled leaves of this selection are splashed irregularly with purple across the surface and undersides. Plants grow to a little over 2 feet high and may spread to as much across; I produce all plants from cuttings to maintain the best character­istics. Flowers are a delightful pink on a dark stalk 3 to 4 inches long; the leaves give off a sweet anise scent that has olfactory echoes of the Italian green basil called Napoletano, which I suspect is somewhere in the background of Purple Ruffles. Holly’s Painted is excellent in salads and makes a colorful garnish for fresh fruits.

New Guinea Basil

O. b. ‘New Guinea’ is a delightful little plant 12 to 16 inches high with narrow, pointed, anise-scented leaves that look like inch-and-a-half-long arrowheads; their dark purple centers fade gradually to green at the slightly toothed leaf ­margins. The undersides are reddish purple. The lavender flowers with dark violet throats grow in a loose purple spike. This basil’s background is mysterious. Kim Kuebel, a Texas herb collector, is apparently responsible for distribution of seed to commercial growers in the United States. According to Kuebel, the English botanist John K. Morton, a professor at the University of Waterloo in Ontario, mailed him a packet of New Guinea basil seeds in 1980. “All the packet said was ‘Lae, New Guinea’,” Kuebel told me. In a telephone interview thirteen years later, Dr. Morton, a precise man of few words, could not remember sending the seeds nor where they came from, but he speculated that a European colleague, since deceased, may have collected the seeds in New Guinea and shared them with him. New Guinea basil grown from seed (currently available from Companion Plants) produces a few variants, most of which resemble Dark Opal; others have ruffled leaves that are deeply ­serrated and have the appearance of a demure Purple Ruffles.

A Note on Basil’s Genetic Variability

All these purple-leaved basil varieties are fine plants, but there is one thing wrong with most of them: they are rarely uniform when grown from seed. As an experiment, two years ago I selected a Dark Opal plant as typical and reproduced it from cuttings; I then harvested seed from these carefully segregated plants and raised a crop of seedlings; I thought this might give me an idea of the natural variation in the plant. To my surprise, 18 percent of these offspring were green or variegated; 24 percent were, to my hypercritical eye, a pale purple/green combination, while the remaining plants were dark purple. Unfortunately, some seed available for purple-leaved basil varieties has considerably more variability than did my test seed. The purple basils with the least variability in my trials were New Guinea and the large-leaved Genovese Grande Violetto; other growers indicate that Rubin is in this category, too, although I have not tested the seed myself. Variability has some advantages because it allows the gardener to pick the style of growth, and the leaf and flower color that is most suitable for a particular garden situation and personal preference; the selections may then be propagated from cuttings. If you’re a stickler for uniformity and want dark purple plants, it might be best to carefully select from the garden center or herb specialist a few plants that meet your standards and then take cuttings from them.

Uniformity from seed is not the only problem facing basil growers. The lower leaves on purple basil plants have a tendency to drift to green over a summer of growth; this is especially true if the plants have not been provided with strong sunlight and if nitrogen levels have not been maintained in the soil or the container. Frequent pruning of the plant deep down the stems also helps to renew the purple color with new leaves. (Even green basil plants often have better color in the top leaves than in the lower, older leaves.)

The genetic variability of purple basil seed as it comes from the pack can get hopelessly crazy; just ask Rose Marie Nichols McGee of Nichols Garden Nursery in Albany, Oregon. While any gardener who has ever planted a packet of purple-leaved basil seed has seen variability, McGee saw her prized seed stock of Burgundy Beauty diluted by genetic variants over two years until it disappeared. She told me she had first spotted what was to become Burgundy Beauty on a visit to Alan Kapuler at Peace Seeds in Williams, Oregon. This striking new plant caught her attention with its robust appearance and large, relatively smooth, long maroon leaves with deeply serrated margins. Nichols and Peace Seeds both produced seeds of the variety in 1989 and 1990, isolating the seed stock from other basils and roguing out atypical plants. Despite this devotion to maintaining varietal integrity, “We had a couple of good generations,” said McGee, “before we lost it.”

The genes that cause purple in basil appear to be so unstable that even vegetatively propagated plants can lose their purple color. I tried for years to maintain stock plants of those delightful purple-splotched plants produced from seeds of Purple Ruffles, but, alas, the leaves eventually turned green. Then one spring, a seedling with a purple blush in a flat of green Greek basil struck my eye. The adult plant had a medium-sized, pointed leaf, considerably larger than that of Greek basil, and from the base of the leaf, purple spread like a thumbprint until it feathered itself into the green of the midsection of the leaf. I called the plant Carrie’s Violet Blush basil for Carrie Fortescue, who worked unblushingly for me a number of years and had noticed the seedling while transplanting in the greenhouse. I propagated the plant vegetatively for several years, and then one spring the stock plants turned green; this occurred, coincidentally, the same year Carrie left for Kansas.

The story of Carrie’s Violet Blush doesn’t end there, however; the same summer she left, a purple variant showed up in a flat of Thai basil seedlings that was to take the prize for variability. At the branching of a single stem were two distinctly different forms: one had a puckered wide, rounded leaf blotched with purple over a light green background while the other held leaves that were smooth and green and pointed with an area next to the stem that was suffused with purple just like Carrie’s Violet Blush.

The kind of variability shown by purple basils can cause heartache for commercial growers and consternation for home gardeners, but it also opens many opportunities for new varieties. I don’t think we should stop producing purple basil seed because of it, but the natural variability and unpredictable nature of many purple-leaved basils does seem to call for some production changes. After growing purple basils for nearly twenty years, it’s my opinion that nurseries should produce these stunning purple-leaved annuals from cuttings rather than seeds to preserve the uniformity of the plants they sell. Unfortunately, I don’t believe this change will happen soon because of the additional expense of vegetative propagation and the ready availability of inexpensive, if variable, seed.

My summer of purple-leaved basils was an exciting time of personal and horticultural discovery. For many years, my attitude toward herbs was that if a plant was practical, I liked it; if it was merely beautiful, I wasn’t interested. Now I had all these purple-leaved basils that were both practical and beautiful, and I found them enchanting. These fickle little purple-leaved herbs also allowed me to see varietal creation in a new and more organic way, and the force of randomness and chance in nature took on new importance. The “creation” of lovely, exciting new herb varieties is still largely chance even when tempered with a breeder’s knowledge, and the randomness of these varietal changes, for all its charm and mystery, makes one wonder if other, less inquiring eyes have not viewed the beauty of these changelings in some lost and wild past.

While I have always relished uniformity, I gained a new appreciation of the untamed essence of many herbs with their frustrating and lovely ability to re-create themselves by seed with unexpected variations. These simple basil plants with their iridescent purple leaves reminded me of humanity’s inability to tame even this small part of nature. (Is it any wonder that we are unable to civilize the rest of the world?) Now when life seems hopelessly out of control, I retreat to the herb garden with all its daring and unpredictable variety and realize how helpless and fulfilled we can be in the arms of nature.

Sources of Purple Basils

• Companion Plants, 7247 N. Coolville Ridge Rd., Athens, OH 45701. Catalog $2.
• Richters, Goodwood, ON L0C 1A0, Canada. Catalog $2.50.
• Well-Sweep Herb Farm, 317 Mt. Bethel Rd., Port Murray, NJ 07865. Catalog $2.

Tom DeBaggio lives in Arlington, Virginia, with his wife, Joyce, and two cats; he makes his living growing and selling potted herb plants on his urban “farm” called T. DeBaggio Herbs. He thanks Dr. Arthur O. Tucker for his patience with dumb questions and willingness to share valuable information.

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