Today’s column comes to you as we head for Italy. We are already missing the tropical ambiance of Hawaii Island and won’t be back until two days before the Nov. 5 election. We especially want to be home for that event.
Palms play an important role in creating a tropical ambiance and some species have graced parts of Italy for hundreds of years due to early introductions by plant explorers, botanists and horticulturists. Palms and other exotics soon found their way in to gardens of the well to do. The most common palm that may be seen as far north as the southern slope of the Swiss-Italian border region is Trachycarpus fortunei or Chinese Wind mill Palm.
Visiting tropical places like Hawaii is the treat of a lifetime to millions of people a year. 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 or Europe. 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. Some folks 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 regions with the selection of tropical looking plants and the right landscape 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 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 those with 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.
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 below zero degrees. The silk tree is native to Asia and can reach heights of up to forty feet but is usually much smaller, spreading like an umbrella to twenty 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. Another close relative of our Ohia (Meterosidos polymorpha) is s specie from New Zealand (Meterosidos tomentosa) that is almost identical but cold hardy. There are probably selections of our Ohia from the high mountains that are also very tolerant of cold.
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 is a great one for the ultra-tropical look. It is relatively fast growing to about thirty 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 in Scotland and France. 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. Sabal Palms and Serenoa repens or Saw Palmetto from the southern United States may also be found in some gardens of palm enthusiasts in Italy.
There are several hardy bamboos that will take temperatures below zero. 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 a protective mulch with a good rich soil and it will grow from six to fifteen 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. Two bananas, Musa sikkimensis and Musa basjoo will also winter over with protective mulch as will our Taro.
The list of tropical looking but hardy plants is extensive. You might consider trees like the hardy Eucalyptus species. These include the Cider Gum and Snow Gum that survive temperatures close to zero.
When it comes to fruits, the fig, pomegranate, olive and loquat can all be found growing as far north as Seattle, Washington on the West Coast and many locations in Italy. When it comes to tropical ambiance, it can be found in the Italian Rivera and even as far north as Switzerland. So as we travel, we feel a little bit of Hawaiian gardening has had an influence in the most unlikely places.
Gardeners 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 garden shops. You may also call the UH Master gardener Helpline at 322-4893 in Kona or 981-9155 in Hilo.
Norman Bezona is professor emeritus, University of Hawaii College of Tropical Agriculture and Human Resources.
