A Gardening Journal

The Best Season Ever: Naranjilla

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This Ecuadorean relative of the tomato defines "fierce beauty." The huge fuzzy foliage is studded with purple spines, and the heavy stems bristle with hundreds more. When the green leaves are heavy with dew, they are silvery white.

 

Gorgeous but also territorial, Solanum quitoense demands to be appreciated, carefully, from as close a range as you dare.

 

The plant is subtropical, and self-seeds readily as long as seeds and plants are both kept frost-free. The plant in the picture below is a volunteer in a large potted purple-leaved pineapple lily, which overwinters, dormant, in the basement.

 

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There's quite a contrast—collision is more like it—between the chilly purple and silver foliage of the Solanum and the sunny yellow-leaved forms of ornamental raspberry in the front and paper mulberry at the back. Better color partners for the Solanum include pink, blue, burgundy, and white. In the picture below, burgundy-leaved ninebark, silver-leaved fountain buddleia and, at the back, the subtle pink of the immense cloudy flower clusters of variegated tree angelica all contribute to the easy and yet dramatic harmony.

 

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Mature foliage of Solanum quitoense is the breathtaking silver in the pictures above because it's covered with dew; when the weather is warmer and the humidity lower, the large leaves are green. The small young foliage is still an intense silvery-white, thanks to its thick covering of fuzz.

 

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The round shapes at the base of the leaves are flowerbuds. They, too, are completely covered in fuzz—but some of it is lavender.

 

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The flowerbuds open into modest white flowers, held so close to the spiny stems that only an agile, careful, and small pollinator could access them safely.

 

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The flowers develop into round fruits the size of ping-pong balls. When ripe, they become juicy and turn orange, giving away this plant's near relative, the tomato.

 

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In its native South America, Solanum quitoense is grown as a fruit crop. Thankfully, there's a spineless form, so the fruits can be harvested without blood loss. They can be eaten out of hand, or juiced into a tangy drink whose flavor recalls, not tomato, but citrus. Hence, the Spanish common name: "Naranja" is the orange citrus fruit."Naranjilla" is the word's diminutive, literally, "little orange."

 

Here's how to grow this prehistoric-looking subtropical shrub:

 

Latin name

Solanum quitoense

Common name

Naranjilla "nah-RON-hee-yah" / Lulu

Family

Solanaceae, the Potato family.

What kind of plant is it

Subtropical herbaceous short-lived shrub; can also be grown as an annual.

Hardiness

Zones 10 to 11.

Habit

Upright, wide-spreading, shrubby.

Rate of growth

Very fast.

Size in six months

From seed, young plants can become impressive shrubs three to four feet tall and wide. With ideal conditions—see "Culture," below—naranjilla can mature to a bulky shrub six to eight feet tall and wide. Shrub or not, individuals of the species are not long-lived: Five to seven years is usually the upper limit. 

Texture

Lush but threatening, with sharp-bristled stems bearing huge fuzzy leaves that are studded on all sides with inch-long spines. The plant is so well armed it doesn't have to worry about being browsed.

Grown for

its large spiny foliage: The foliar spines are purple, and are so strong and so profuse—on the bottoms as well as the tops of the leaves—that they give pause. Just how rough a neighborhood is this plant's native habitat in low mountains in South America? Leaves can be eighteen inches long, with a gently scalloped edge, and are as striking at a distance as they are at close range. They are green, but are covered with a rough fuzz that gathers a myriad of tiny drops of dew; in the morning, the foliage is a shimmering silver. The contrast with the purple veins and purple spines is thrilling.

 

its fuzziness: New growth of the plant is densely covered in trichomes—that's the latin for hairs—that are lavender-purple when they emerge, and quickly change to white.

 

its vigor and size: Seedlings grow fast, and starter plants at a nursery are usually sold in one-gallon containers. Provide encouraging conditions—see "Culture," below—and you can expect a mighty shrub by August.

 

its aggressive vibe: Solanum quitoense shares the same "Cool, eh? Now, stand back!" appeal of the thorniest succulent. Most plants that are highly thorny have leaves that are comparatively small or quickly dropped—think cacti, roses, pyracantha, locust trees, and citrus—and the plants' prickles are formed on the stems and trunk. Plants with larger foliage that also would seek to protect that foliage with thorns or spines would need to bear them right on the leaves themselves; think agaves, with razor-sharp teeth along the edges of their sword-like leaves, and a painful spine right at the tip.

 

The leaves of Solanum quitoense are wide as well as large. Even the largest thorns on the stems and the fiercest spines along the leaf edges wouldn't begin to protect them. Hence, the solution of naranjilla: Spines arise all over the leaf surface, top and bottom, erupting with precision spacing from the outer surface of the leaf veins. Despite the network of spines, there is still a lot of leaf surface that is unprotected if you are small or nimble enough to work between the spines. Naranjilla would seem, therefore, to be arming itself against foraging by megafauna, the large herbivores, such as those that are plentiful in Africa and Asia: Elephants, horses, bears, cattle. Megafauna in South America, the native range of Solanum quitoense, were wiped out millenia ago; naranjilla is still at the ready should the need arise. To my knowledge, the plant's protective strategy for its large and wide leaves is unique.

 

Protection also extends to the flowers and fruit. The flowers are on very short stems that emerge at the base of the leaf. No animal larger than a pollinating insect is likely to be able to access the flowers, or the small round orange fruit, juicy as their tomato relative, that they mature to. Fruit also have a fuzzy or even bristly surface that further repels any but a committed and strategic attempt at harvesting and eating. Ripe fruit are heavy for their size, and when they fall from the shrub they could roll a short distance away. It's no surprise that naturally-occurring plantings of naranjilla are often in multi-plant colonies. It's also no surprise that spineless forms of naranjilla are preferred when the plant is grown agriculturally. 

 

its imperviousness to browsers: Given the shrub's comprehensive prickliness, as well as the fuzziness of the foliage and fruit even if you can, somehow, get past the spines and the bristles, naranjilla foliage is safe from predation. Your garden is not plagued by the megafauna that naranjilla is armed against—now-extinct South American giant sloths and tapirs, for example—but it may well be visited by hungry deer, woodchucks, and rabbits. They'll all leave Solanum quitoense alone.

Flowering season

As an annual, mid-Summer to frost. Born at the base of the large leaves, the flowers are not showy. They mature to small round orange fruit, similar in size and coloring to cherry tomatoes—if those tomatoes also had fuzz, that is—that are curious more than showy.

Color combinations

The purple spines, white flowers, lavender trichomes, and (when be-dewed) silvery foliage make naranjilla an easy partner to pink, blues, whites, and burgundies. The orange fruits are visible from high Summer through frost, and have just enough presence to make Solanum quitoense a daring partner  to oranges and reds, too. Only yellow seems left out of the possibilities.

Partner plants

Naranjilla is almost agnostic about the color of its near neighbors, and its prehistoric persona makes most flowers (its as well as theirs) seem either prissy or irrelevant. Instead, pair with plants based on the strength and diversity of the interactions among their foliage. If the colors are similar, the contrasts of size, shape, and texture can be all the sharper without becoming discordant.  

 

Grassy foliage is the natural contrast to big foliage (spiny or fuzzy or not). The plumes of Muhlenbergia capillaris are pink, a cousin of the lavender of the naranjilla's trichomes. The foliage of Pennisetum setaceum 'Rubrum' or Saccharum officinarum 'Pele's Smoke' is burgundy, as are the sword-like leaves of purple forms of Phornium tenax; burgundy is a cousin of the purple of naranjilla's veins and spines.

 

I often plant Solanum quitoense in an elevated planter, with the narrow silver foliage of Buddleia alternifolia 'Argentea' to the back, and the maple-like dark burgundy foliage of Physocarpus opulifolius 'Summer Wine' at the front. Stunning. This Summer, I'll add  Gynura aurantiaca to the planter. It's the only plant I can think of with fuzz that is even more dense and bright purple than that of naranjilla. The plant's habit is scandent; stems would be as welcome if they find their way up into the Solanum as if they cascade from its base. Gynura has small apetalous orange flowers that usually look weedy. Naranjilla's odd orange fruits will finally have have some coloristic company that's a match in misfittity.

 

It might be interesting to experiment with growing Solanum quitoense in dappled shade; the resultant foliage might be even larger. Shade-tolerant partners with foliage or stems that are either burgundy or silver include Hedychium greenii and many forms of Begonia and Fuchsia. Someday I'll plant a pot of naranjilla that I place at the base of my potted 'Summer Chocolate' mimosa. The tree's lacy canopy would provide dappled shade; its leaves' dark purple color would combine well with the lavender and white of the Solanum. Even better, the mimosa's peculiar flowers, seemingly of nothing but pink-and-white filaments, would echo the lavender-and-white fuzz of the Solanum.

 

Avoid pairing naranjilla with plants with similarly large foliage; the look would be heavy as well as repetitive.

Where to use it in your garden

Solanum quitoense is large as well as distinctive, and would be difficult to use as anything but a focal point. You're unlikely to have access to nematode-resistant plants (see "Propagation," below); the seed-grown ones that are usually available will be highly susceptible. Plant in a (very) large container to protect from possible attack.

 

Any shrub-sized plant in a large container automatically has considerable presence. A huge tub of naranjilla would be the star of any garden.

Culture

Full sun in climates where temperatures are rarely above ninety degree Fahrenheit; dappled shade is better where temperatures are hotter. Rich but well-draining soil. Plants are quickly intolerant of poor drainage. Better in very large containers in climates and habitat where nematodes can infest the soil. Check with your local office of the USDA Cooperative Extension Service to determine if nematodes are a problem where you're gardening.

 

Here is more information than you can imagine on a century of efforts, quixotic to date, to grow naranjilla as a food crop in the Caribbean and North America.

How to handle it: The Basics

Plant in Spring only when any danger of cool nights, let alone frost, is past. Because sheer size is part of the appeal of naranjilla, any steps to reduce early-season shocks, as well as to encourage steady growth, will be rewarded with bigger, larger-leaved, and more impressive specimens.

 

Buy starter plants at the nursery as soon as they become available, to minimize their chances of being pot-pound. Repot right away, in a two- or even three-gallon container of potting soil that is compost-enriched and nematode-free. Keep the plant in a sunny window or greenhouse until weather is settled and benign. If necessary, repot into a still-larger container. When warm weather is assured, place the permanent container where it will stay for the season, and then plant the by-now shrubby naranjilla in it. Use as big a container as is practical and attractive; a fifteen- to twenty-five gallon container is not too large!

 

Water as needed, while still allowing the soil surface to become dry between waterings. Add fish emulsion to the water twice a month.

 

Thankfully, given the plant's comprehensive prickliness, such usual tasks as pinching or deadheading are not necessary. Reach into and beneath the shrub to remove spent leaves. It would be worth it to have a pair of giant rubber-tipped chopsticks for the job; try wrapping the tips of a pair with thick rubber bands. Wear gloves and long sleeves when handling Solanum quitoense; even spent leaves and dead stems are painfully prickly.

 

After frost kills the shrubs, dig them out of their soil. For a species whose roots are supposed to provide insufficient anchoring when grown agriculturally, the shrubs are powerfully rooted into potting soil. In my experience, plants cannot simply be pulled from the soil even when you have maximal leverage and are wearing heavy gloves. Chop all around the "trunk" of the shrub with a sharp spade, and use a soil knife to complete the job of releasing the roots.

How to handle it: Another option—or two?

Solanum quitoense grows so quickly that there is little need to attempt overwintering. Even if it were easy to move a plant in such a large container into shelter, the plant's forbidding spines would make it a dangerous space-hog.

Any (other) quirks or special cases?

None.

Downsides

As is often the case with plants in the Solanum genus, S. quitoense is extremely susceptible to attack by nematodes. These tiny soil-dwelling creatures are not generally found in climates colder than Zone 7 but, even so, naranjilla grows well in large containers, so why risk planting in-ground?

Variants

There are many indigenous forms where naranjilla is native, varying in degrees of spininess as well as in the color of the trichomes. Spineless forms are planted where naranjilla is grown agriculturally, in Peru and Ecuador. The spiniest forms are reported to occur in northern Columbia and up into Central America. The form available in North America certainly seems aggressively armed, but who knows what the extreme is? Given how colorful the leaf spines are, forms with spines that are unusually long or profuse would be welcome.

 

Many forms of Solanum are native to South America, tomato and potato among them. There are a number of species closely related to Solanum quitoense, all with similarly large foliage (usually not spiny), and juicy fruit (often larger but not as flavorful). They all hybridize.

 

Availability

Seeds are available on-line; young plants are available, rarely, at specialty and "destination" nurseries. To my knowledge, only a moderately-thorny form, identified only as Solanum quitoense, is available as an ornamental in North America.

Propagation

By seed. When grown as a fruit crop, Solanum quitoense is often propagated by grafting seedlings onto Solanum species whose roots can better support the plant, which are reported as becoming top-heavy and vulnerable to wind. Species with nematode resistance are also important; hybrids of Solanum quitoense and Solanum sessiliflorum combine much of the tastiness of the fruit of S. quitoense with the nematode resistance of the roots of S. sessiliflorum.

Native habitat

Solanum quitoense is native to subtropical (but still frost-free) uplands of northwestern South America and southern Central America: Columbia, Venezuela, Ecuador, Panama, and Costa Rica. Quito is the capital of Ecuador; the latin name means "the solanum from Quito."   

 
 
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