JARS v63n4 - Regional Musings: Rhododendrons in Florida

Regional Musings: Rhododendrons in Florida
Jim Norquest
West Palm Beach, Florida

Reprinted from the Vireya Vine, #86, July 2009)

"It is not nice to garden anywhere. Everywhere there are violent winds, startling once-per-five-centuries floods, unprecedented droughts, record-setting freezes, abusive and blasting heats never known before. There is no place, no garden, where these terrible things do not drive gardeners mad."
- Henry Mitchell, The Essential Earthman

Gardening in Florida must be paradise, right? No frost, no snow, constant sunshine, balmy breezes...I mean, they named the place "Florida," which means "land of flowers", so.

Well, let me enlighten you. Florida is not all peaches and cream, garden-wise. First of all, much of the time it is HOT. Not balmy, not just warm, but hot. And humid. I mean soggy, Turkish-bath humid. Day and night. From mid-May through late October the average nighttime low temperature does not drop below 21°C (70°F). And from mid-March through late November the average daytime high temperature is over 27°C (80°F). West Palm Beach, my fair city, is in AHS heat zone 11, which means that we have 180 to 210 days per year above 30°C (86°F).

And then there is the "soil," which is just glorified sand. At certain times of the year we have day after day of blustering, desiccating winds. With no frost, we get fire ants and a thousand other pests. We have clouds of blood-thirsty mosquitoes. And I haven't even talked about the hurricanes.

This is what I faced when we transplanted ourselves to Florida from the north some years ago, leaving behind a small but much-loved rhododendron collection. At first I sulked. (My wife says this phase continues.) But eventually I decided that I was here for the duration and I'd better make the best of it. Besides, I could not not garden! I never lost my love for rhododendrons but I was not foolish enough to imagine that I could grow my old favorite evergreens here. I did try for years to grow deciduous azaleas, especially a few of the more southern-ranging natives. Results: death. Sometimes quick, sometimes lingering, but always death.

Finally a few years ago I came across an article about vireyas, and a light came on. But of course - tropical rhododendrons! Incredible colors, a wonderful multitude of forms, sizes, growth habits, foliage types. They seemed to be the ideal solution, a way to satisfy my continuing love for rhododendrons in this dismal climate. And so they have been. Vireyas are vastly exciting and rewarding to grow, but they are not effortless in Florida. Mistakes were made, as the politicians say.

I began by ordering a number of beauties based almost entirely on flower color. The results were initial enchantment, often followed by disappointment. Some of them promptly died during their first summer in paradise. A few just slowly declined or simply did not thrive, looking sulky and unhappy, but most died suddenly, almost certainly of phytophthera or one of its nasty cousins. I tried different planting mixes, new pots, new fertilizers, different exposures and levels of sunlight - with the same results.

I am nothing if not persistent. Eventually I went back to basics and began reading and studying everything I could get my hands on about vireyas. What I learned is that many of the species and hybrids I had bought had their genetic origins in high elevation areas of the tropics where days may be warm and humid but nights are cool if not cold. The varieties I had purchased were simply not suited to my growing conditions. The gardener's age-old dilemma!

Well, I may be a slow learner but I do learn. I began keeping careful notes from the literature about vireya species that originate at lower elevations, and their hybrids. I also began to note species that occur over a wide range of elevations, and over wide swaths of geography, figuring that this indicates toughness and adaptability. I read accounts by other tropical gardeners and especially vireya growers in various places in the world. I watched "good-doer" lists from areas with warm climates. Ultimately I compiled a list of species and hybrids which should, theoretically at least, do well here, and I began ordering my plants from this list instead of just picking what caught my eye.

The results have been more than gratifying. Over the last few years my losses have dropped nearly to zero, and I am enjoying unprecedented success with vigorous growth and, of course, flowers. We just finished another south Florida summer and (knock on wood!) I have not lost a single plant except for a couple of my own weakly-rooted cuttings.

I have also continued to refine my growing techniques. I grow most of my plants in containers because it is easier to control the soil that way, and to move the plants when conditions warrant.

I use a loose pine bark or cocoanut chip-based mix. I prefer clay pots, especially orchid pots because the openings provide better air circulation to the roots. Many of the larger plants are plunged pot and all into raised beds of sawdust to keep the roots cool. However, the long term viability of pot culture is questionable as the plants get bigger. We shall see.

Water is a continuing concern. We get about 1524 mm (60") of rain a year but the majority of it comes during the summer, and winters are usually dry and often windy. Our municipal water is alkaline and full of nasty chemicals. Fortunately, we have a well which provides better water. During the hot months and windy periods, the plants dry out quickly, and a few days without rain or supplemental watering lead to quick death. This makes vacations a tricky proposition. I also do not like to water too much during our long humid periods because I think it encourages disease.

The trickiest growing variable, however, is light. There seems to be a great variation in light requirements for vireyas. Two varieties situated side by side may result in heavy bloom on one and hardly any on its neighbor, so one eventually must be moved to a more exposed spot. At this latitude the sun will be directly over head during summer and scorching hot, so plant placement is crucial. You must give them enough sun to encourage flowering, but too much leads to excessive drying and wilting or requires more water than I like to give them.

When the plants are properly selected and their needs are met, however, vireyas in south Florida are very rewarding. Looking back over the past three years during which I have kept records, I find that at least one variety has been in bloom every month of the year, with peaks of blooming activity during March/April, September/ October, and December/January. A few varieties have shown bloom during five months of some years; others are much shyer. Interestingly, the peak bloom periods vary from year to year, while still generally conforming to the pattern of heavier concentrations in spring and fall. It will be fun to see how these patterns hold up over time as the plants mature.

Even though my plants are still relatively young, certain hybrids are already certifiably "good doers" for me. These include an unnamed Schick hybrid from Bovees identified as V66 ( R. laetum x R. zoelleri ); the hybrid ('Cherry Liqueur' x 'Narnia') incorrectly referred to by some with the epithet 'Ring of Fire', which is not valid for this cross as it is actually the registered name of an elepidote rhododendron; 'Haloed Gold' ( R. christianae x 'Tropic Glow'); 'Kisses' ('Tropic Glow' x ( R. viriosum x R. macgregoriae ); and 'Dawn Chorus' (same cross). Others showing promise include 'Tango Time' ( R. macgregoriae x R. christianae ) and 'Popcorn' ( R. macgregoriae x R. loranthiflorum ). Although I love them, no species have yet made it onto the list of stars.

I would welcome news and advice from vireya growers with similar conditions. There don't seem to be many of us here.

Jim Norquest
Jim Norquest is a member of the Hawaii ARS Chapter.