The tropics, grown against the odds. Sub-tropicals bring bold leaves, vivid flowers, and a whiff of the jungle to gardens well north of the frost line, thriving through a hot Southern summer and, with a little shelter, holding on through the cold.
'Pam Puryear' is the soft-pink small Turk's cap, a lovely departure from the usual fire-engine red of this tough native mallow. The furled, never-quite-open flowers keep the charming Turk's cap form, less than two inches long and produced without pause through the hot months, but here they glow a gentle shell pink that reads cool and quiet in the summer border.
The purple firespike answers a quiet complaint of the warm-climate gardener, that the tropical border runs to reds and hot corals and forgets the cooler end of the spectrum. Odontonema callistachyum carries erect spikes of tubular, lavender-to-amethyst flowers at the tip of nearly every branch, each spike lengthening to almost a foot as the buds open in succession from fall into spring. The genus name joins the Greek odous, a tooth, with nema, a thread, for the small toothed filaments within the bloom, while the epithet callistachyum means, simply and accurately, beautiful spike. The leaves are broad, glossy, and faintly fleshy, a lacquered dark green that holds the plant together as a handsome mound even between flushes.
Podranea ricasoliana, the pink trumpet vine or Port St. John's creeper, is a fast-growing evergreen climber from the warm regions of South Africa, a member of the trumpet-creeper family, Bignoniaceae, prized for showy, trumpet-shaped flowers.
Polygala x dalmaisiana, the sweet pea shrub, is a fast-growing evergreen hybrid of two South African species (P. oppositifolia and P. myrtifolia), grown for a nearly year-round show of orchid-like flowers on an open, informal frame.
The Sunquat began as an accident in a Beeville, Texas dooryard in the early 1940s, when a man named Leslie Cude noticed a seedling carrying fruit that looked like a small lemon and behaved like a kumquat. Walter Swingle, the great citrus authority of the day, took one look and guessed a cross of Meyer lemon and kumquat, which is where the name Lemonquat comes from and how it entered the collections as Citrus limon × Fortunella. The trouble is that the curators who have kept the tree at Riverside ever since have come to doubt him. The fruit, they think, points to a mandarin somewhere in the parentage rather than a lemon, which would make the plant a mandarinquat wearing the wrong label. Nobody has settled the question. The plant has gone out as Sunquat, Lemonquat, Lemondrop, and Marmaladequat, four names for one tree, each a different theory and not one of them proven. Asking a citrus to hold still long enough to be classified rather misunderstands the family.
Tibouchina granulosa, the purple glory tree, is a Brazilian showstopper long grown in Florida and the warm South, a large shrub or small tree in frost-free gardens and a root-hardy dieback perennial where winters brush freezing. Glossy, deeply pleated, prominently veined leaves set off the flowers, which come smaller but far more abundantly than those of the better-known princess flower, Tibouchina urvilleana, so the whole plant seems dusted with purple through the warm months.
Woodlanders has long been a leader in offering citrus and citrus hybrids hardy well beyond the usual citrus belt, and the 'Razzlequat' is one of the odder and hardier of the lot. The plant is a cross between the Australian desert lime, Eremocitrus glauca, a tough, drought- and cold-tolerant native of the arid Australian interior, and, most likely, the familiar 'Meyer' lemon. From the desert lime parent come thorny, wiry branches, small narrow gray-green leaves, and a hardiness and drought tolerance rare among citrus; from the lemon come size and flavor.
A cold-hardy citrus with a Woodlanders pedigree. Woodlanders has long led in offering citrus and citrus hybrids that stand outdoors beyond the usual citrus belt, and the calamandarin is one of the toughest. Likely a hybrid of a mandarin, Citrus reticulata, and a calamondin, the calamandarin blends easy-peeling, tangerine-like fruit with the cold tolerance that calamondin brings to the cross.
A hardy evergreen ginger of unsettled name, this Alpinia forms dense, upright clumps of lance-shaped leaves that hold their fresh green right through the year in a mild climate, bringing a lush, tropical structure to the shade garden. In the warm months, bright yellow flower spikes rise above the foliage for an unexpected lift of color in deep shade.
Called Philippine violet, though neither Philippine nor a violet, Barleria cristata is a showy subtropical shrub that saves its display for the close of the year, opening dark blue-violet, trumpet-shaped flowers through late summer and autumn when much of the garden is winding down. A perennial in zones 8 and 9 and a four-to-six-foot shrub in zone 10, native to India and Myanmar.
Hardiness
Zones 8–11
Light
Full Sun / Part Shade
Height
4–6 ft.
Spread
24–30 in.
Bloom
Blue
Plant type
Shrub
Traditional use
respiratory support, topical applications, pain relief, general wellness
Native to Central and South America but naturalized across the tropics, this fast-growing shrub flowers not in spring or summer like a well-behaved plant but in autumn and into early winter, hanging great loose clusters of clear, saturated yellow at the ends of arching branches, each bloom built around curved stamens that give a vaguely butterfly-like silhouette. Cloudless Sulphur and Sleepy Orange butterflies find the shrub irresistible as both nectar source and larval host, and tend to arrive in numbers when the flowers open, a fact that either delights or mildly alarms a gardener, depending on how attached one is to the foliage. The caterpillars, for the record, are a vivid chartreuse and genuinely handsome. That is the bargain on offer.
'Buttercream' is a pale yellow-flowered form of Cassia bicapsularis, a softer, more refined take on that shrub's late-season show. Where the species blazes a saturated gold, 'Buttercream' carries clusters of cool, buttery cream-yellow flowers through autumn and into early winter, the same butterfly-like blooms at the ends of fast, arching branches, and the same draw for Cloudless Sulphur and Sleepy Orange butterflies that feed and breed on the plant.
September is a difficult month to write for. The garden is still technically in summer, but the light has shifted, lower and more golden, arriving at an angle that changes everything it touches. Cassia corymbosa reads that shift and answers it. While most summer shrubs are winding down, this one is only beginning, throwing dense corymbs of deep golden-yellow flowers at the branch tips with an enthusiasm that seems almost contrarian for the season.
Cestrum elegans var. smithii is the soft, blush-rose form of the elegant cestrum, a fast, arching shrub that carries dense terminal clusters of slender tubular flowers in a warm pink, mildly fragrant in the evening and a steady draw for hummingbirds. Where the species runs to hot red-purple, this variety keeps things gentler, blooming from late spring well into fall, and year-round under glass.
Few plants announce themselves the way Cestrum nocturnum does, and never by daylight. Through the afternoon the shrub keeps to a quiet, almost ordinary green, the slender branches arching and half-climbing, the small tubular flowers furled and unremarkable. Then dusk arrives, the cream-green trumpets open, and the night-blooming jasmine releases a perfume so far-reaching that it carries across a whole garden on still, warm air.
The Ponderosa lemon is grown for spectacle as much as for the kitchen. The fruits are enormous, often two to four pounds each, thick-skinned and gloriously bumpy, hanging like green-gold cannonballs among the glossy leaves. For all the size, the flesh is tart, juicy, and true lemon in flavor, and works in any recipe a regular lemon would, with the novelty of a single fruit that can fill a hand.
The Rangpur is not truly a lime at all, but Indian gardeners have used the fruit as one for more than five hundred years. Citrus x limonia, an old natural hybrid of mandarin and citron, bears small, round, deep orange fruits that look like tangerines and taste fiercely sour, with the aromatic bite that makes a fine lime substitute for cooking, cocktails, and marmalade. In India the fruit goes by surkh nimboo, the red lime, prized for exactly that intense, tart juice.
Among the very first of the citranges, Citrus 'Rusk' dates to 1897, when Walter Swingle crossed a Ruby orange with the tough, cold-hardy trifoliate orange, Poncirus trifoliata, in the great effort to breed citrus that could take a freeze. The result is a vigorous, tall-growing, notably hardy tree, evergreen to semi-evergreen, and dense with the distinctive three-parted trifoliate leaves.
Named for Walter Tennyson Swingle, the pioneering citrus breeder who spent his career crossing tender oranges with the iron-hardy trifoliate orange, the Swingle citrumelo is among the toughest citrus hybrids ever raised. A cross of grapefruit, Citrus paradisi, and trifoliate orange, Poncirus trifoliata, this vigorous, thorny, semi-evergreen shrub or small tree carries fragrant white citrus blossoms in spring, followed by pear-shaped yellow fruits about the size of a large orange.
Woodlanders has long led in offering citrus and citrus hybrids hardy well beyond the usual citrus belt, and the Troyer citrange is a classic of the kind. A cross of the Washington navel orange and the inedible but iron-hardy trifoliate orange, Poncirus trifoliata, the Troyer was raised in 1909 under the direction of the great citrus breeder Walter Swingle, and later named for A. M. Troyer of Fairhope, Alabama, where the tree first bore fruit, a nice southern footnote for a hardy citrus.
