THE COASTAL GARDENER:

Pretty soon, when you turn the handle on your water spigot or your automatic sprinkler systems turn on, what will come out may be just a little bit different. When you fill your sprinkler can to water your indoor plants, they won’t be getting quite the same water to which they are accustomed.

By now many of you are aware of the Metropolitan Water District’s announcement that fluoride will be added to our water as an aid to the prevention of tooth decay. Sounds great; fluoridation of municipal water supplies has been a practice in many communities around the country for the past 50 years. Until now, Fountain Valley and Huntington Beach have been the only Orange County cities that artificially add fluoride to their water.

On Nov. 19 about half the households in the county will receive fluoridated water. Since some communities receive their water from groundwater supplies, at least at certain times of the year, not everyone will be affected in the same way.

The subject of artificially introducing fluoride into our water supplies has been debated hotly for years. It is a contentious debate, with newspapers, radio talk shows and the Internet overflowing with enough science, facts and opinion that at times either side sounds equally convincing.

Almost all of the municipal water fluoridation discussion involves debate about dental health, medical studies, toxicology data and so on. I certainly will not weigh in on these issues; I can add nothing.

But I have been asked if there will be an effect on our plants or our gardens. I do have some thoughts in this area, where I am at least a couple of rungs up the tall ladder of knowledge.

The average person only drinks a very, very small fraction of the water used in a day. But not only the water going into our mouths is being fluoridated; all of it is.

If all the water is fluoridated, how much fluoride is winding up in our gardens and our environment, and what are its effects?

Fluoride does not break down — it accumulates. While most plants will not show any adverse effect from the extra fluoride, plants vary in their sensitivity and some are adversely affected by even very small amounts — levels bellow the 0.7 milligrams-per-liter that the water district will begin maintaining in our municipal water supply.

Fluoride may be great for our teeth, but it can present problems for some of the plants we grow as gardeners. Many of the most sensitive plants belong to two families, liliaceae and marantaceae, but other species are also affected.

Leafy tropical and foliage plants can especially show adverse symptoms. These plants include chamaedorea elegans (parlor palm), chrysalidocarpus lutescens (areca palm), chlorophytum comosum (spider plant), cordyline species, ctenanthe oppenheimiana, pines, lilies, maranta (prayer plant), aglaonema (Chinese evergreen), spathiphyllum (peace lily), yucca and especially dracaena (including lucky bamboo).

The most common symptoms of fluoride toxicity in these and other plants include a chlorosis or yellowing of the tips and margins of older leaves, followed by dry or dead portions.

Ever wonder why many plants at nurseries, especially leafy tropical and indoor plants, look so green and the leaves are so perfect all the way to the tip? Then, after a few months at home, still under good care, the luster is gone and the tips and edges begin discoloring, drying and browning?

Several reasons, and a significant one is that professional growers do not use tap water to irrigate.

Professional growers either use pure well water or, more often, they run their water through a complex reverse osmosis process, which removes most of the sodium, fluoride, chlorine and other dissolved solids in our water. In other words, at least for professional growers, our water is good enough to drink, but they wouldn’t dare water their plants with it.

The addition of fluoride to our water supply also creates a unique dilemma for serious organic gardeners. Since fluoride has an affinity to attach to organic matter, such as fruit or vegetable surfaces, the organic gardener would probably not be able to rinse the fluoride off. Because a reverse osmosis system is expensive and impractical for most homeowners, the organic gardener now has a new challenge to contemplate.

ASK RON

Question: I need a simple, low maintenance, low-water ground cover suggestion for a large, steep slope.

Marty

Costa Mesa

Answer: Baccharis pilularis “pigeon point’ is an outstanding low-water, noninvasive ground cover. It is a selection of a native species, so it is California Friendly and well-adapted to our climate. It tolerates seaside conditions, alkaline soil, sand, clay and deer. “Centennial” is another selection that grows a bit taller. Planted in the fall, baccharis will establish and fill in well by next summer.

ASK RON your toughest gardening questions, and the expert nursery staff at Roger’s Gardens will come up with an answer. Please include your name, phone number and city, and limit queries to 30 words or fewer. E-mail stumpthegardener@rogersgardens.com, or write to Plant Talk at Roger’s Gardens, 2301 San Joaquin Hills Road, Corona del Mar, CA 92625.

RON VANDERHOFF is the Nursery Manager at Roger’s Gardens in Corona del Mar.