JARS v60n4 - Hawaii's Public Vireya Garden or Looking to the Future

Hawaii's Public Vireya Garden or Looking to the Future
R.A. "Mitch" Mitchell
Volcano, Hawaii

"That isn't a rhododendron! I'm from the Northwest and I know what a rhododendron looks like," said a visitor to our garden. Ever since then I've been determined to let people know more about vireyas*.
Her remark really got my attention, but I guess I was too polite to remind her that vireyas make up almost half of the known rhododendron species, not to mention innumerable hybrids.
This incident took place back in the mid-1980s soon after I began growing vireyas in my garden at 4,000 feet (1200m) two miles from one of our active volcanoes, Kilauea, near the little village of Volcano. How I got started and what motivated me I outlined in an earlier article in this journal (1997, Vol. 51, No. 3).
As my vireya collection continued to grow so did my enthusiasm as well. And so did the number of visitors who saw their vibrant colors in our garden for the first time. Inevitably there came a point when I began to wish that our area had a public garden where we might share our vireya enthusiasm with a larger number of plant people.
So in 1999 when Hilo's director of the Panaewa Rain Forest Zoo and Botanical Garden extended the invitation to our Hawaii ARS chapter to create a vireya garden we took it seriously. He explained that the Palm Society, Bamboo Society and Water Garden Society had previously made major plant contributions: why not vireya rhododendrons?
We recognized that the Zoo's location at about 500 feet (150m) elevation above Hilo (northeast side of the Big Island) would provide an ideal opportunity. It is a public facility maintained and administered by the County of Hawaii and admission is free. Most importantly it is a relatively secure facility with adequate parking. Here the public could visit the garden at their leisure and see vireyas planted in a natural setting. We were thrilled, but how to begin? To give us a sound basis for our planning we called on Bill Moyles for advice. We were aware of his successful development of the Lakeside Vireya Garden in Oakland, California. At a meeting of our chapter at the Zoo we surveyed with him the possibilities and he gave us his opinion. For the location he recommended a bank of mostly porous volcanic rock that would provide the perfect drainage required for successful vireya cultivation. This bank was conveniently located near the front entrance and would (he felt) provide a most attractive welcome to Zoo visitors. Naming it "Bill's Bank" seemed a natural, and the name has stuck.

But this was only the beginning of what was to be an arduous task of site preparation including the removal of a number of unwanted weed trees. As soon as Bill's Bank was cleared we planted many hybrids donated from our members' gardens in order to create as rapidly as possible Bill's "attractive welcome to Zoo visitors."
The second phase began about two years ago with some major landscaping. This included rock walls to create a raised species bed and planting began with donations from members of several dozen species. This was the beginning of a species collection we hope will reach a total of about 150 plants. About the same time members began rooting cuttings from their species plants which were earmarked for transplanting when they are sufficiently matured. (Note to potential visitors: while this process is underway it seemed logical to use the presently empty space as a Test Garden to monitor a number of hybrids crossed by our members.)
All in all the area allotted for our public vireya garden comprises a space of perhaps one acre. Its maintenance is largely a labor of love by our member volunteers. You might want to keep in mind that when our chapter got started in the '90s there were very few of us who had been smitten by the vireya palette. For a long time orchids claimed first place in Hawaiian horticulture with anthuriums coming in a close second. However, after the formation of the ARS Hawaii Chapter in '97 more and more vireyas began appearing in local nurseries and in several annual flower shows including that of the popular Hilo Orchid Society.

This growing popularity was helped immensely by the appearance of visiting vireya experts whom the chapter invited to be speakers at its meetings and seminars. They came from the U.S. mainland, Australia, New Zealand, the U.K. and Germany. They left delighted in seeing vireyas growing in the open without the need for frost protection. Chapter members on this island garden in a variety of microclimates. Several of us are at the highest elevation of just about 4,000 feet (1200m) on the southeastern side. Most of the others are located at lower elevations down to about 500 feet (150m) near the Zoo garden. One member lives on the west side at about 1,500 feet (450m). And we know of another garden with a nice collection of vireyas and hardy rhododendrons in the central part at about 6,000 feet (1800m).
Before going further, perhaps an introduction to our growing conditions might be helpful. Ours is the largest and southern-most part of the seven Hawaiian Islands chain. Its latitude of 20 degrees puts it north of Mexico City and south of San Diego. Elevation ranges from sea level to the top of Mauna Kea (13,796 ft., 4180m) and is "located in a region where descending air inhibits the formation of deep clouds. Were the islands without steep sloped high mountains, rainfall would range between 22 and 28 inches (57 and 70cm) per year" (Atlas of Hawaii). Clearly without this help from Mother Nature there wouldn't be sufficient moisture to support much plant life including vireyas.
Rainfall varies considerably from year to year. In the rain forest location of our garden we have seen 250 inches (625cm) when it rained 24 inches (60cm) in 24 hours. However, the normal average is closer to 170 inches (425cm). Of course, if it weren't for our lava rock sub-strata these figures would spell disastrous flood conditions. On top of the lava rock in our garden we are lucky to have about 4 feet (120cm) of humusy soil with a pH of around 5.0. Some not-so-lucky residents at our elevation are forced to garden with just a few inches before they reach lava rock and can still grow vireyas outdoors.

Temperatures at our 4,000-foot elevation also vary considerably from year to year and month to month. We have seen lows in the mid 30sF (-1.1C) at night in the winter months, but they will increase to the 70sF (21.1C) by noon. In the summer months we have seen the low 90sF (32.2C) in the afternoon drop to the mid 50sF (10C) in the evening. We have never seen a frost at our elevation, but at a subdivision just 300 feet (90m) higher there will be three or four frosts in an average winter.
At the Zoo garden location near sea level the 10-year average rainfall was 140 inches (350cm) where the highest figure was 212 inches (530cm) in 1994, and the lowest was 101 inches (252cm) in 1995. Temperatures average 81F (27C) with an average minimum of 66F (19C) (low of 63.6F and high of 68.9F) and an average maximum of 81F (27C) (low of 79F and high of 83.8F).
As you might suspect our various climate conditions create growing differences. The cooler nights seem to slow growth at the higher elevations compared to those in the warmer areas. General statements are usually risky, but the warmth and additional light of the lower elevations seem to produce flowers on some vireyas faster than on the same varieties at higher elevations. And of course there is concern that the climate seems to be getting warmer with more frequent drought periods which dictates that good moisture control is essential.
To summarize: the status of our public vireya garden at the Zoo in the autumn of 2005 as compared with our beginning in 2000: Bill's Bank is covered with dozens of mature hybrids which make quite a sight to visitors first merging from the entrance. Just as we originally predicted their exclamations range from, "My word, what are those plants with such beautiful and vibrant colors?" to "Where in the world did those gorgeous plants come from?" After they have moved further along the path they soon come to a display that explains some of the information they seek.

* Rhododendrons in section Vireya.

Mitch Mitchell is a member and past president of the Hawaii Chapter.