Cold Hardy Tropicals

A young needle palm

About Rhapidophyllum Hystrix
Rhapidophyllum hystrix, the needle palm, is generally considered to be the most cold-hardy palm. It is a slow-growing palm with a shrub-like form, and usually does not form a large trunk. It is indigenous to the coastal southeastern United States, from Mississippi to South Carolina.
Hardiness
Conservatively, the needle palm is hardy [...]

Cannas, gingers, and elephant ears are generally hardy to zones 7-8, and should be treated as annuals in colder climates. They share the common characteristic of having a large underground rhizome or tuber. Their cold hardiness can be increased by topping them with a heavy layer of mulch in the winter. In climates [...]

While many annuals share a tropical origin, certain plants are especially useful for giving the tropicalesque garden a certain punch. They can be mixed in as accents with hardier plants. Even using just a few of these annuals along with other cold-hardy tropical looking plants can provide a dramatic effect in the garden. [...]

These tropical-looking plants don’t quite fit into the other categories – small, tropical-looking deciduous shrubs, hardy citrus, eucalyptus, and yuccas. They work well with evergreen trees and shrubs, and deciduous trees to create a permanent framework for your tropical garden.
Dediduous Shrubs, Yuccas, and More:

Buddleia davidii (Butterfly bush) : Zone 5-10
Hibiscus syriacus (Rose-of-sharon) : Zone [...]

Tropical-looking deciduous trees are valuable because they are typically large and easy to grow, creating a framework around which other tropical-looking plants can be arranged. The tropical effect may come from large, exotic-looking leaves; palm-like, finely-divided leaves; or some other feature, such as interesting flowers, fruit, bark, or branch structure.
Deciduous Trees

Albizia julibrissin (Silk tree [...]

Many varieties of trees and shrubs are valuable in a tropicalesque garden for their tropical-looking foliage, flowers, or general habit. Some trees and shrubs are fully hardy, yet add a tropical aura to a landscape. Certain trees and shrubs that have been traditionally grown in warmer areas, such as the southern United States, are [...]

A dramatic, tropical-looking grass can make a great accent or mass planting in your garden.

Arundo donax (Giant reed) : Zone 6-10
Arundo donax ‘Variegata’ (Variegated giant reed) : Zone 6-10
Carex muskingumensis (Palm sedge) : Zone 4-9
Chasmanthium latifolium (Northern sea oats) : Zone 4-8
Erianthus ravennae (Plume grass, Hardy pampas grass) : 5-9
Hakonechloa macra ‘Aureola’ (Japanese forest grass) [...]

Adding a backdrop of climbing vines will give your garden a lush, tropical rainforest look.

Actinidia kolomikta ‘Arctic Beauty’ (Hardy kiwi vine) : Zone 4-8
Akebia quinata (Chocolate vine) : Zone 4-9
Aristolochia macrophylla (Dutchman’s pipe) : Zone 4-8
Bignonia capreolata : Zone 6-9
Campsis radicans (Trumpet creeper) : Zone 5-9
Clematis x hybrida (Clematis): Zone 4-8
Humulus lupulus ‘Aurea’ (Golden hops) [...]

Cold-hardy ferns, especially the larger varieties, can add a tropical look to your garden.

Adiantum pedatum (Maidenhair fern) : Zone 2-8
Athyrium filix-femina (Lady fern) : Zone 2-9
Athyrium niponicum (Japanese painted fern) : Zone 5-8
Dennstaedtia punctilobula (Hayscented fern) : Zone 3-8
Dryopteris filix-mas (Male fern) : Zone 4-8
Matteuccia struthiopteris (Ostrich fern) : Zone 2-6
Osmunda regalis (Royal fern) : [...]

These tropical-looking perennials are excellent for filling in your tropicalesque garden with low-maintenance areas.

Aspidistra elatior (Cast-iron plant) : Zone 6-10
Belamcanda chinensis (Blackberry lily, Leopard flower) : Zone 5-11
Bergenia cordifolia (Heartleaf bergenia) : Zone 3-8
Crocosmia (Montbretia) : Zone 6-10
Eucomis ‘Sparkling Burgundy’ (Purple Pineapple Lily) : Zone 6-9
Euphorbia epithymoides (Cushion spurge) : Zone 4-8
Helleborus (Hellebores) : Zone [...]