Tropicals for Temperate Gardens

Today’s hottest horticultural trend is all about tropicals. Avant gardens boast big-belled daturas and brugmansias, shamanistic plants from South America whose huge, flaring flowers look like something Ginger Rogers would wear. Red and green banana trees and paddle-leaved cannas are again admired as they were in Queen Victoria’s day. Although few truly tropical plants are hardy here in the Northwest, many grow exuberantly enough to grow as fabulous, showboat annuals, even when our interesting climate provides less than tropical temperatures. Thus, a jungle garden full of flagrant, flaunting foliage and flowers is surprisingly easy to accomplish.

The tropicals trend has created an interrelated series of new and still developing garden styles. All combine large-leaved plants with potently architectural lines, yet they vary in ambience and planting pattern. Like true jungle understory, Hardy Tropical gardens spill over with dramatic foliage. Groupings of boldly scaled plants create an exotic treeline with strong lines and powerful mass. Mediterranean Basin gardens combine palm trees and sun roses (Cistus) with silvery evergreen herbs in gravel-based dry gardens that suggest the shimmering heat of Southern Italy, Greece, and North Africa. Big, blatant flowers that look gaudy in prim borders fit perfectly in salsa-based Tropicalismo gardens, which glory in gigantism and extravagance. They also celebrate Pan and the panic; that neck-prickling recognition of the ultimate dominance of Nature.

Most tender tropicals can be coddled indoors over the winter, where they should be treated as evergreen houseplants. Give them plenty of light, along with regular but moderate water and food, and many will grow as happily indoors as out. Indeed, a well-fed angel’s trumpet may bloom all winter, though less generously than it would in high summer.

If you can’t imagine growing tropical plants in the garden, an angel’s trumpet or blue glory bower will make a splendid introduction to the exuberant pleasures summer tropicals can offer. These eager growers can put on six or eight feet in a couple of months and begin producing flowers very quickly. To give them a jump start, provide ample food and water on a regular basis. Then stand back, because they grow FAST, especially where summers are warm. In cooler gardens, place tropicals in large, deep containers, where an extra degree of warmth will encourage rapid root growth. Remember that timed-release fertilizers don’t become activated until soil temperatures reach the 70’s; thus, coastal gardeners may need to supplement with fertilizer spikes or liquid feeds in early summer.

ABUTILON Flowering maple is grown for the dangling, full-skirted bell flowers which flower in a delicious array of colors. The maple-like foliage is equally attractive, especially in the variegated forms. These do best in partial or light shade, where the muted colors develop fully without scorching. Flowering maple makes an excellent pot plant, moving readily indoor and out each season. Pinch back in spring to reduce legginess.

ALOCASIA amazonia ‘Compacta’ Luxuriant and sleek of leaf, taro looks delicious in borders or containers. Protect these fabulous foliage plants from wind and scorching sun, but offer plenty of light, water, and warmth to get the greatest growth. Taro roots are edible, but the bold foliage is even more delectable, especially in combination with red bananas, bright-striped cannas, purple Persian Shield, and silvery plectranthus. Midnight dark, white-veined ‘Black Widow’ makes for instant drama with lime green ‘Margarita’ sweet potatoes and variegated orange Abutilon. Lusty Alocasia x calidora boasts five foot long leaves when pleased. Compact, green-leaved ‘California Shield’ is perhaps half that size, but utterly reliable and can be hardy to zone 8 in mild years, as is the narrow-leaved ‘New Guinea Shield’. Compact Amazon taro produces boldly marked purple leaves with white-veining, a natural companion for riots of Purple Wave petunias and swags of Arabian jasmine. Slim ‘Portodora Shield’ looks splendid with swirling Fountain Rush and hardy hibiscus.

ALPINIA zerumbet ‘Variegata’ Majestic variegated shell ginger belongs to the rich flora of subtropical China. Tall stems may reach 8-10 feet, with long, lance-shaped leaves. In summer, showy clusters of white, purple-tinted flowers produce an enticing perfume. Shell ginger prefers filtered or partial shade and blooms best when given plenty of water and light but regular feeding. Both in containers and in the ground, open-textured, humus-rich soils will encourage fast growth.

ALTERNANTHERA Calico plant or parrot leaf was a favorite of our grannies, who grew these fancy-leaf foliage plants indoors and out. Today, these playful plants are indispensable ingredients for those who love filling the pockets of ornate knot gardens or recreating intricate Victorian bedding-out patterns. Most make small mounds or run in low, spreading ribbons. All grow well in containers or in the ground, enjoying full sun or light, partial shade, deep, rich soil, and lots of water.

BREYNIA Rose snowbush has enchanting, rounded leaves, dappled with white, rose, and green and set like delicate coins on slim stems. The pronounced zigzag pattern of the leaves makes a handsome contrast to strappy, broad-bladed carexes and boldly patterned coleus. A shrub in its South Pacific homeland, this lovely foliage plant rarely achieves great size in the Northwest. For best performance, give Breynia rich, well-drained soil and light shade, with protection from drying winds.

CALATHEA warscewiczii Costa Rica is home to hundreds of ornamental plants, among them this dazzling prayer plant. The striking foliage of ‘Jungle Velvet’ is boldly striped in green and purple with burgundy backsides. A natural understory plant, Calathea thrives in moist shade but prefers well-drained soils. It grows well in containers and can overwinter indoors with ease.

CENTRATHERUM intermedium Brazilian button flower is a plump, bushy shrublet that blooms at the stem tips all summer long. Small but profuse, the fluffy, lavender-blue blossoms are set off by deep green leaves with neatly pinked edges. In less than full sun, pinch any leggy stems to keep plants compact. In hanging baskets, let the lax stems tumble over the sides.

BRUGMANSIA & DATURA The angel’s trumpet clan is gaining popularity in a hurry. The family has two main divisions; tree-like Brugmansias, whose great bell flowers dangle downward, and shrubby or herbaceous Daturas, whose flared trumpets face up. Both are splendid growers that only want the best of everything—full sun, plenty of water and lots of food—to give of their own astonishing best. In both groups, the flowers may be single or double, ruffled or flaring. The color range is wide, but largely limited to soft tints, running from white and cream to yellow and peach, salmon and pink, rose and mauve, lilac and muted purple. A few flower in exotic combinations like dim purple lined with café-au-lait. The large leaves are generally unremarkable except for size, but some Daturas have handsomely lobed leaves and certain Brugmansias are marbled with butter and cream.

DURANTA Skyflower adapts readily to a wide range of garden conditions, taking dry or damp soil, sun or light shade in stride. A small tree in South America, it rarely exceeds 3-5′ in the Northwest, where it makes a compact, open-textured shrub that blooms on arching, feathery wands, exchanging flowers for fat little fruits as summer matures. Skyflower prefers water to food and grows quickly in any decent soil.

ENSETE Red Abyssinian banana has enormous and lovely leaves of bottle green stained with ruby and port. Try this fast grower alone or pair it with tree ferns and masses of swirling ‘Sparkler’ carex. Grown in borders, this is considered a relatively hardy banana. To help it along, give it a tall hoop of hog wire filled with straw and dried leaves in late fall (add a handful of smelly moth flakes to keep hungry rodents at bay). Uncover in spring and watch those huge new leaves unfurl. Baby bananas are not unknown, but don’t expect ripe, mature ones!

EUPHORBIA millii Crown of Thorns is a succulent, shrubby Asian spurge with showy red and chartreuse bracts. This is a terrific performer in dry, warm places, where it produces many bloom-tipped arms over a very long season. It takes wind, full sun and lean soils in stride, and performs well in sunny seaside gardens. It can overpower less architectural companions, but looks wonderful with coppery carexes, swirls of ponytail grass (Stipa tenuissima), and tall sedums such as ‘Autumn Joy’.

GRAPTOPHYLLUM Caricature Plant is an evergreen shrub Down Under, where it may reach six feet. Northwestern summers rarely coax such great growth from this handsome foliage plant, but its glossy, hand-sized green and yellow leaves look great anyway. In warm years, look for plump purple and red flowers (hummingbirds love them).

HAMELIA Mexican fire bush offers brilliantly flame colored flowers set off by bronzed and ruddy foliage. It blooms well when young and may reach 3′ by midsummer, particularly in pots. Well drained soil is a must, and it prefers to dry out a bit between waterings. Try it with maroon ‘Jack Spratt’ New Zealand flax, sky blue salvias & trails of ‘Purple Bells’ Rhodochiton.

HIBISCUS Rose mallow makes a boldly shrubby shape in the garden, where it may reach 5′ in a summer. The dusky red leaves set off its glowing mahogany flowers to perfection, and the plant makes a striking accent against ‘Lime Mound’ or ‘Goldflame’ spiraeas. Rose mallow gets leggy in shade, but takes full sun with aplomb if given rich and well-drained soil.

IPOMOEA Sweet potatoes have come a long way from the kindergarten window sill. These stunning foliage plants fill baskets or weave wondrous carpets of long-fingered foliage in glowing chartreuse, sage with cream and rose, or near black. Full sun, tilthy soil, and excellent drainage make them gloriously happy, in the ground or a pot. Mix these stunners with upright fuchsias, let them drip over a low wall, or mingle them memorably with small New Zealand flax.

IRESINE Bloodleaf is prized for its fancy foliage, which may be pleasingly puckered or painted in dashing streaks and stripes of red and purple, gold and cream. Most forms achieve a foot or two of height, making them splendid candidates for mixing into marvelous container combinations with ruffled coleus, shimmering copper carexes or black mondo grass, and gilded streamers of golden creeping jenny or buttery yellow immortelle.

JASMINUM Most powerfully scented of all the jasmines, Arabian jasmine has lacy, glossy foliage and waxen, creamy flowers that smell like pure romance. The blossoms turn rosy purple as they mature, giving them a pretty two-tone effect. Use Arabian jasmine for a quick summery screen for a trellis or wrap it through climbing roses and clematis trained over a bower seat. It isn’t as hardy as some jasmines, but even a single summer’s bloom is an unforgettable treat. Dry the flowers for pot pourri or add them to green or black tea blends. You can also mix them with lemon balm and spearmint for a delicate, refreshing herbal tea.

KALANCHOE behariensis Velvet elephant ear has the vast, felted foliage the name suggests, while K. thyrsiflora is an exotic looking South African succulent that looks as if brushed with silver frost. The soft green, red_edged foliage is crisp edged and neat, forming lapping wedges that suggest shelf fungi set sideways in the soil. The odd shape combines well with firmly shaped tufting grasses, low sedums, and dwarf iris. The cool yellow bell flowers are most fragrant on still, warm days, when the scent can carry surprisingly across the garden. Give both types plenty of warmth, good drainage, and lean soil, and avoid excess water in summer. Easy to overwinter indoors or in a moderately warm greenhouse.

LEONOTIS Lion’s tail is a semi-evergreen South African that is a fitful perennial but an utterly reliable annual. Its slim stalks carry stacked bobbles of tawny red flowers above slender foliage. These attract hummingbirds in season and remain structural and attractive well into winter. It does best in full sun and dry, lean soils, and does not tolerate crowding in jampacked borders.

MUSA Dwarf bananas make splendid pot plants and can also be grown in the ground. Fast growing and shapely, the bananas throw offshoots called “pups” in warm summers. These can be detached and grown on as houseplants all winter, then taken outside as warmer weather arrives. Both ‘Dwarf Cavendish’ and ‘Zebrina’ have large, red-streaked foliage and may produce their yellow, red-tinged flowers in warm summers. To encourage quick growth and protect leaves from shredding, give bananas shelter from wind and harsh sun, provide plenty of water on a regular basis, and feed them lightly every few weeks.

PANDOREA Beauty bower grows with ardent good will, lacing trellis or tree with a leafy embrace. Full sun and a deep run in humus-enriched, promptly draining soil will encourage rapid flowering, which is good, because the scent of those soft pink or white flowers can make a summer evening memorable. Give this determined scrambler a favored spot against a sunny wall and you won’t be sorry.

PASSIONFLOWER Fast growing, free flowering passion flowers will live happily in a tub for a season or two, but where hardy, they prefer to grow in tilth-rich, well-drained garden soil. A sunny, wind-sheltered spot works best in cooler climates, where these robust vines will smother a fence or leap up a trellis in a summer. Such an ideal position may coax a plump, juicy fruit or two from the fabulous flowers during a warm year (but don’t count on it unless you have a greenhouse or sunny enclosed porch to offer).

RUELLIA Mexican Wild Petunias come in several forms. Uprights are shrubby, slim-leaved plants, while compact types make showy little mounds for border edging or containers. All are heavy bloomers that produce serial flushes of open, flaring bell flowers in white or a range of pinks and purples. Ruellias thrive in light, airy positions where they receive direct sun only in the morning, if at all. They require excellent drainage, but flower hardest when constantly supplied with water and mild fertilizer.

SENECIO confusus An attractively casual scrambling twiner from Mexico, this evergreen dusty miller cousin offers sequential bursts of fragrant, reddish orange daisies all summer long. In the wild, it may reach 20 feet. In the Northwest, it won’t, but let it have a go anyway. Give it a trellis in full sun and see how far it gets before frost arrives. It’s South African cousin, S. macroglossus ‘Variegatus’, is called Cape Ivy for its climbing ways. Also evergreen, this one has wedge-shaped leaves edged and veined in butter and cream and ivory, unscented flowers. Give this one shade from afternoon sun to protect the lovely variegation.

SETCREASEA Purple heart or Moses_in_a_Boat is a familiar houseplant that can be grown in beds and borders, where it is occasionally hardy. This trailing perennial has saturated purple foliage, folded and cupped, with vivid violet stems and hot pink flowers. They color best in bright light, though they grown well in partial or filtered shade. Mix these with red and coppery coleus, pink forms of Sedum spathulifolium, and masses of rosy super petunias, which make suitably exotic, luxuriant companions.

STROBILANTHES Persian shield is a sumptuous foliage plant whose large, deeply embossed leaves are glazed with a lustrous sheen of pewtery purple. Wine_red undersides make them especially showy when perched in a tall pot or set on a deck where the plants are often seen from beneath (set their skirts with purple Million bells petunias for a knockout display). To reach its usual 3-4′, Persian shield needs rich soil and plenty of food and water. It grows most luxuriantly in a warm, sheltered spot where it gets ample indirect light.

THUNBERGIA Sky flowers are vigorous, thrusting scramblers that can wind their way up a tree or trellis in a single season. Glossy, heart-shaped leaves set off large, lightly scented tubular flowers of summer sky blue. In the Northwest, these lusty creatures need full sun, rich and well-drained soil, ample water and frequent food to offer their best performance.

TIBOUCHINA In it’s native Brazil, glory bower makes a large shrub or small tree. In the Northwest, this rapid grower reaches 3-4′ in a summer, smothering itself beneath an extravagance of vivid, purple-blue flowers. The velvety leaves are napped with red-gold or bronze silk when young, and take on rich color as fall draws near. Glory bower likes acid, sandy soils, but prefers a pot of decent soil to native clay. It revels in a warm garden nook, but needs protection from harsh winds near the sea. Hide its leggy looks by threading a morning glory through its lower limbs.