Global warming means palms in surprising places

We are still in Italy but soon to be home. Visiting the Amalfi Coast south of Rome made us homesick mainly because it looks tropical with lots of palms, bananas and other plants that create a tropical ambiance. It just goes to show that one can create a feeling by the plants used in the landscape.

A visit to Hawaii is the treat of a lifetime to millions of people a year, and many folks who come are friends or relatives of those of us who live here. One of the highlights for them is to experience the lush tropical gardens and forests that are unlike any place in the continental United States. Many folks who enjoy gardening go home wishing they lived in a tropical place where they could have yards and homes filled with palms and other exotics. Visitors don’t have to be discouraged. With a little help from Kamaaina gardeners, they too can have a piece of paradise back home. Some mainlanders create a mini oasis with lots of houseplants. Others even build solariums or small greenhouses to get their tropical fix, but ambiance can be created in colder parts of the country with the selection of tropical looking plants in the right design.


The air of freedom and informality in Hawaiian gardens is partly due to the exotic plant materials used. It is also due to the casual style of design found throughout the Islands. This consists of mixing many bold and colorful shrubs, ground covers and trees in a relaxed, unregimented manner. This type of landscaping gives a sort of well maintained jungle effect.

The best part is that the hang loose look can be done anywhere there is a place to grow things. It can be achieved with almost any plants, but to develop that kind of look, the selection should be with those that have a bold lush look. There are very hardy warm temperate trees like some species of Rhododendron, Magnolia and Camellia that can give the tropical effect. This combined with global warming has allowed gardeners to grow some plants for example, that could not be grown in the region 100 years ago.

Of course it is expected to see that tropical look along the gulf coast or southern California. You may even see a tropical ambiance along the Atlantic coast as far north as southern Virginia, but not expected in places like Oregon, Washington and British Columbia. However, landscape designers and adventurous gardeners have pushed the envelope to include regions that would surprise you.

One tree that is finding its way northward is the Albizzia julibrissin or Persian Silk Tree. Although very tropical in appearance, with its Poinciana like foliage and pink pompon flowers, this tree will tolerate conditions down to 0 degrees. The silk tree is native to Asia and can reach heights of up to 40 feet but is usually much smaller, spreading like an umbrella to 20 feet. The tree’s filtered shade allows grass and other plants to grow underneath. It also makes a very good patio tree.

The Gingko biloba or Maidenhair Tree is another from China that will tolerate sub-zero temperatures. This tree is a living fossil from the era when tree ferns and palms were growing throughout North America. Cities like New York are using them as street trees to reduce the negative effect of concrete and asphalt.

When it comes to palms and ferns to create a tropical look, there are those that are fairly hardy. If you live in an area where temperatures seldom reach ten degrees or colder, the Trachycarpus fortunei or Windmill Palm is a great one for the ultra-tropical look. It is relatively fast growing to about 30 feet. This palm should be used in groups of three to seven for a dramatic effect. The many healthy specimens in Seattle, Washington attest to this tree’s ability to withstand cold. They may even be found Switzerland. Another much slower palm that is equally hardy is the Chamaerops humilis or European Fan Palm. This clumping type has been known to sustain temperatures of six degrees above zero. There are several other palms that will grow as far north as Coastal Oregon.

There are several hardy bamboos that will take temperatures below 0. Close relatives of bamboo like the Arundo from the Mediterranean can be used in areas where temperatures are below zero. Although this giant reed may freeze down in winter, give it protective mulch with a good rich soil and it will grow from 6 to 15 feet in a summer. Another popular bamboo relative is Pampas grass or Cortaderia sellowana from Brazil and Argentina. This versatile clumping grass will tolerate dry to wet soils and temperatures close to zero if protected by mulching.

At least two species of banana may be grown as far north as British Colombia. These are Musa bajoo and Musa sikkimensis. They may freeze down in the winter but when protected by heavy mulch, they will emerge in the spring like their close relative, the Canna lily.

The list of tropical look-alikes goes on. You might consider trees like the hardy Eucalyptus species. These include the Cider Gum and Snow Gum that survive temperatures close to zero. Yuccas like Yucca gloriosa, Hostas, Fatsias, numerous vines and many other plants with bold foliage can be of use as well.

When it comes to fruits, the fig, pomegranate, olive and loquat can all be found growing as far north as British Columbia on the Pacific Coast.

Your mainland friends can experiment with these and others that nurseries and garden centers carry or try some from more southerly locations. To avoid discouragement, check with garden books that cover plant hardiness. One good reference is Sunset’s Western Garden Book that may be found in book and garden shops.

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