Many gardeners desire a lush, tropical garden aesthetic, even in temperate climates with significant winter chill. Achieving this look requires selecting plants with dramatic textures, oversized foliage, and vibrant colors that can withstand the cold. Success depends on strategically blending plant selection with an understanding of climate classification and proper winter maintenance.
Understanding Cold Hardiness Zones
The survivability of perennial plants is determined by the USDA Plant Hardiness Zone Map, which guides gardeners based on the average annual extreme minimum winter temperature. Each zone represents a specific temperature range. A plant rated for Zone 7, for example, is more cold hardy than one rated for Zone 10, but its survival is not guaranteed if planted in a colder zone.
Zone ratings establish the baseline for what a plant can tolerate, but local conditions, known as microclimates, can significantly alter this potential. Microclimates are small areas within a garden that have differing atmospheric conditions from the surrounding region. For instance, a sheltered spot near a south-facing masonry wall acts as a heat sink, raising the minimum temperature. Cities also create “urban heat islands” due to concrete and pavement, providing a slightly warmer environment. Understanding these localized variations allows gardeners to strategically place borderline plants for improved winter survival.
Structural Plants for Exotic Foliage
Structural plants provide the immense scale and dramatic silhouettes necessary for a tropical garden illusion. The Japanese Fiber Banana (Musa basjoo) is a prime example, offering characteristic paddle-shaped leaves up to six feet long. Although the above-ground foliage dies back with the first hard frost, its robust rhizomes are reliably cold hardy down to Zone 5 if protected. This vigorous herbaceous perennial quickly regrows each spring from its underground base.
Palms are quintessential tropical markers, and cold-tolerant varieties can anchor the garden design. The Needle Palm (Rhapidophyllum hystrix) is one of the most cold-hardy palms, surviving in Zones 6 through 11, and occasionally Zone 5. It forms a shrubby clump of deeply divided, fan-shaped leaves but lacks a visible trunk. The Windmill Palm (Trachycarpus fortunei) is another excellent choice, surviving in Zone 7, and Zone 5 with protection. It is recognizable by its slender, fibrous-wrapped trunk and large, rigid fan fronds.
Bamboo also contributes vertical structure and lush density. Clumping varieties, such as Fargesia dracocephala, are the safest landscape option as they spread slowly and predictably. These bamboos are cold hardy to Zone 5 and produce a dense, weeping canopy of foliage, creating an evergreen screen. For ground cover, the T Rex Hosta provides enormous, corrugated green foliage that delivers an impressive, jungle-like look in Zones 2 through 9.
Vibrant Accents and Companion Plants
Vibrant accents add color and complex texture to complement the structural plants. Elephant Ears (Colocasia) are popular for their massive, heart-shaped leaves, which range from deep green to almost black. Most varieties are tender, requiring lifting in zones colder than 8. However, the cultivar ‘Pink China’ is cold hardy to Zone 6 with proper mulching and is identifiable by its bright pink stems.
Cannas provide bold foliage and brilliant flowers, often featuring striped or variegated leaves. Varieties like ‘Tropicanna’ thrive in Zones 7 through 11, producing large, orange blooms above richly colored foliage. Depending on the zone, their rhizomes must be dug and stored or heavily mulched in the ground. The Hardy Ginger Lily (Hedychium) offers exotic color and fragrance, producing showy, yellow or orange flower spikes in late summer. This architectural perennial is reliably hardy in Zone 7 and provides a lush, vertical element.
The Hardy Hibiscus (Hibiscus moscheutos) is an excellent selection for color that withstands a wide range of temperate climates. This herbaceous perennial is known for its dinner-plate-sized flowers in shades of red, pink, or white. It dies completely to the ground in winter but reliably returns in spring. Cold hardy down to Zone 5, it provides a stunning bloom that fits the tropical aesthetic. These flowering accents should contrast with the large, dark green leaves of structural plants to maximize visual impact.
Protecting Tropical Look Plants in Winter
Winter protection is necessary for plants operating at the edge of their hardiness zone, even when using cold-hardy cultivars.
Mulching Underground Storage Organs
For herbaceous perennials with underground storage organs, such as Cannas and Elephant Ears, the roots must be insulated from deep freezing. An effective method is applying a thick, loose layer of mulch, such as straw or shredded leaves, over the crown after the first hard frost. This insulating layer traps residual heat in the soil and prevents damaging freeze-thaw cycles.
Protecting Above-Ground Structure
Plants with above-ground structure, like Windmill Palms or tree ferns, require physical protection. Palm trunks can be wrapped with breathable materials, such as horticultural fleece or hessian cloth, to prevent desiccation and cold damage to the growing point. For tree ferns, the vulnerable growing tip at the top of the trunk is protected by pushing dry straw down into the crown.
Lifting and Storing Tender Tubers
For the least cold-tolerant species, such as most Colocasia or Gunnera tubers in Zone 7 and below, the safest method is lifting and storing them. After frost kills the foliage, the root ball is dug up, dried, and stored in a cool, dark, and dry location. They are often packed in peat moss or sawdust until spring planting. Additionally, watering plants deeply before a predicted freeze helps, as moist soil holds and radiates heat more effectively than dry soil.