Monday, August 21, 2006

"Hosta" La Vista?

Time for a little rant. Okay, I'm a word nerd. I like to use the right word in the right place and it bugs me when I come across words that have been used incorrectly. I do crosswords, sudokus, cryptograms, and other puzzles and it REALLY gets on my nerves when I find spelling or usage mistakes in those. So, last night I was working on a crossword in one of the Big John's Puzzle Books (which I like because the cultural references tend to be aimed at my baby boom generation) when I found two pet peeves in one crossword clue and had to give up out of frustration.

The clue was something like "hearty plant." First of all, plants are "HARDY" -- as in able to survive in extreme conditions -- not "HEARTY" meaning jovial. Those words seem to be used interchangeably, especially by people who aren't avid gardeners and have simply misheard the word. But then when I wrote in the word "hosta" into the crossword spaces I realized it wouldn't work. The puzzle needed it to be spelled "hasta." AAUUGGHH! "Hasta" is a Spanish word, known to most of the English speaking world from the Terminator's famous line, "Hasta la vista, baby!" It is NOT the name of a plant, hearty, hardy or otherwise! It is HOSTA, formerly known as Funkia, sometimes called plantain lily. Also one of the most popular perennials in the U.S., and definitely the most popular perennial for shade. Grrrr.

Sunday, July 23, 2006

Container Crazy

I have no self-control when it comes to containers. My front yard gets hit with full sun all day, so anything in the front has to be able to survive heat, the occasional drought, and sun, sun, sun. Sometimes the heat is too much for me. It's kind of like the porridge in Goldlilocks and the Three Bears. My front yard gets too much sun, my backyard gets too much shade, but the three-level deck is just right.

So, my deck is a garden in itself, with wisteria climbing the pergola -- and after five years or more, it finally bloomed this year! There are masses of hanging baskets and containers of all shapes and sizes. I like the deck to feel kind of like a jungle, so I go very over the top. I have morning glories and clematis in containers, too, so there are climbing plants to add height. I have some built-in containers where I grow shrubs. I mix styrofoam peanuts in with the potting mix to keep it light and aerated, and it seems to work. This year the dwarf Alberta spruces I started in two built-in containers made the move to the back garden, after doubling in size in about five years. I have replaced them with boxwoods and some trailing annuals for a different look this year.

I like to try different exotic plants in the containers, as well as annuals, grasses, herbs, roses and perennials. I will attach some pictures from this year. The container garden has a different look each year because I always like to try new things!

Cincinnati Flower Show 2006

Here are some pictures from the 2006 Cincinnati Flower Show at Coney Island, which is on the Ohio River just across the river from Kentucky. I'm a big fan of this show, which used to be in Ault Park but moved to Coney Island about 3 years ago. I write for the Flower Show magazine on a regular basis, serve on the Ask the Experts panels and usually teach a class or two. The show has something new and exciting every year. The flower show is always at the end of April - be sure to check it out!

Spring at Krohn Conservatory in Cincinnati

As we bake in the heat of midsummer, I'll take a minute to post some pictures taken at the spring show at Cincinnati's Krohn Conservatory. If you've never been to Cincinnati, mark it on your list of things to see. Spring Grove Cemetery and the Cincinnati Zoo and Botanical Garden are two other places to see a variety of plants.

A Garden for Sgt. Matt Maupin

Saturday, July 8, 2006 was an absolutely gorgeous day. The sun was shining, it wasn't too hot - we couldn't have asked for a better day for the dedication of Matt Maupin's garden at Glen Este High School. Matt's birthday was last week and if, as we hope and pray, he is still alive, he turned 23. Matt attended Glen Este Middle School and High School here in Clermont County, Cincinnati and when he graduated in 2002 I, as PTO president at the middle school, had the honor of presenting Matt with a scholarship. I remember him saying he was going to use the money for college. As the mother of two college kids, I know how hard it can be to pay for college.

Well, Matt did use the scholarship money to pay for a year of college at University of Cincinnati - Clermont County. He worked at Sam's Club to help pay his way, but after a year I guess he decided it would be easier to join the service and put himself through college that way. At least that was his plan. He hadn't been in the service long when he was shipped out to Iraq. And he hadn't been in Iraq long at all when he was in a convoy that was ambushed on April 9, 2004. There were many casualties and some survivors were taken hostage, including Matt. A few of the hostages were killed. One of the civilian hostages managed to escape months later. Matt was shown on a video, surrounded by armed captors. About two months later there was a second video, purporting to show his execution. That video was grainy and the person being shot had his back to the camera. No body was ever found, and the Pentagon said the person in the video was too small to be Matt, a tall former football player.

Since then, there have been no further videos of Matt. There has been no word of Matt, no remains ever found, no hint of what has happened to him. If he was indeed executed, what happened to his remains? All of us in his hometown hope and pray that he is still being held somewhere, that he is still alive and will come home soon. Carolyn Maupin, his mom, and Keith Maupin, his dad, have founded the Yellow Ribbon Support Group here, sending packages to our troops on a regular basis. Sam's Club has donated tens of thousands of copies of pictures of Matt in uniform, and pictures of him go out in every shipment, asking the troops in Iraq to keep their eyes open for any trace of Matt. We know the troops all know about Matt, the only member of the U.S. armed forces still missing in Iraq.

To ensure that he is not forgotten at home, we created a garden for Matt in front of the pond and next to the flagpole at Glen Este High School. It was a community effort, with many landscapers donating labor and materials, with volunteers helping to install the plants, and a grant to purchase special benches designed like the American flag. At the garden dedication, a Vietnam vet, aided by a veteran of the Iraq war and by Keith Maupin, performed a flag raising ceremony. The two flags -- an American flag and a POW-MIA flag -- had just been given to the Maupins after they had both been flown over Fallujah in Matt's honor. The Union Township Police Department color guard opened the ceremony, and a recent Glen Este grad played a trumpet solo of the national anthem during the flag raising. Afterwards Carolyn and Keith Maupin cut the yellow ribbon and declared the garden open. Local businesses donated food for a celebration at the American Legion hall after the ceremony.

It was a very moving event. As the garden designer and coordinator, I was very choked up to see all the people in the community who came to the dedication ceremony to show the Maupins that Matt has not been forgotten. It took two years to pull it all together and we would still like to raise funds for a paver "patio" in front of the garden, but the main garden is now open to the public. Thanks to everyone who helped make this garden possible.

Tuesday, June 13, 2006

Extreme Hostas

Photo: Hosta 'Tea and Crumpets'

First published in The Landscape Contractor magazine

“Little and Large: Extreme Hostas,”

By Becke Davis

For years, hostas have been one of the top selling perennials in the United States, competing with daylilies for easy care and familiarity. If you drive around suburban neighborhoods, though, you would mainly see fairly ordinary looking, green and cream variegated, wavy leaved hostas. Even though hostas perform best in shade, you don’t have to look far to see hostas surrounding rural mailboxes, dried out and burned brown.

Planting hostas in the right place is easy enough – most prefer shade, although deep shade is not the best option. Some studies show that more important even than shade is soil that is consistently moist. Hostas in moist soil are better able to withstand the hot sun. Gold hostas are supposed to be more tolerant of sun than blue or green hostas, but no hostas should be the first choice for a site that gets hot afternoon sun and tends to dry out. Filtered shade and rich, moist soil will bring out the best in most hostas. For hostas that are dark green, almost black, nearly full shade is needed to preserve the dark coloration.

Because hostas are common – it would be hard to find a yard without at least one hosta in it – some people equate common with boring. If you have never really looked at hostas, you may be surprised to find hostas that are six feet across, as well as others that, full grown, would fit in the palm of your hand. These extreme hostas – the largest and the smallest of the genus – are not for every landscape, but they can be wonderful, easy care specimens where the site and design allows for their special features.

The chartreuse ‘Sum and Substance’ (60” diameter x 30” high) has drawn media attention for years as one of the best of the big hostas. It has remained near the top of the American Hosta Society’s popularity poll for years, and in 2004 it was selected as the American Hosta Growers Association’s Plant of the Year. Now the focus has shifted to ‘Titanic’ (PP#12,402), a sport of ‘Sum and Substance’ featuring ribbed, variegated foliage with a gold edge and dark green center. The ultimate size of ‘Titanic’ is about four feet high by five feet wide, although some experts believe the size at maturity may reach 80 inches in diameter. Another hosta similar to ‘Sum and Substance’ is the variegated ‘Sum of All’, reaching 60” in diameter and 36” in height. ‘Solar Flare’ is a large hosta with yellow-gold leaves but it doesn’t quite reach the size of ‘Sum and Substance’, reaching only 52 inches wide and 28 inches high.

Some of the better known giant-sized “blue” hostas include ‘Am I Blue’ (45” x 30”), ‘Bigfoot’ (70” x 30”), ‘Blue Angel’ (up to 70” in diameter and 48” high), ‘Blue Mammoth’ (70” x 45”), ‘Blue Umbrellas’ (48” x 36”), H. sieboldiana ‘Gray Cole’ (some experts believe the ultimate width on this cultivar will reach over 84” with a height of 36”), ‘H. D. Thoreau’ (84” x 38”), ‘Krossa Regal’ (72” x 36”), ‘Mr. Big’ (80” x 40”), ‘Sea Blue Leather’ (52” x 36”), and H. sieboldiana ‘Elegans’ (up to about 40” x 30”).
Giant “green” hostas include ‘Abiqua Blue Shield’ (50” x 22”), ‘Behemoth’ (48” x 36”), ‘Bethel Big Leaf’ (56” x 36”), ‘Big Boy’ (48” x 36”), ‘Big Sam’ (48” x 36”), ‘Birchwood Elegance’ (48” x 36”), ‘Colossal’ (48” x 28”), ‘Corduroy’ (60” x 36”), ‘Green Acres’ (52” x 42”), ‘Jolly Green Giant’ (44” x 32”), ‘Placemat’ (60” x 30”), ‘Regal Rhubarb’ (56” x 32”) and H. nigrescens ‘Elatior’ (up to 40” x 30”). ‘Mountain Snow’, a green and white variegated hosta, reaches up to 60 inches across and 28 inches high. The variegated ‘Frosted Jade’ reaches up to 60” wide and 28” in height. ‘Sagae’ is a variegated blue hosta growing up to 70” in width and 30” in height, while ‘Yellow River’ may reach as much as 80” wide and 36” tall.

Among the smallest hostas are the fragrant cultivars ‘Asuka’, ‘Kunpu’ and Otome No Ka’. ‘Fragrant Tot’ has yellow leaves streaked with green and reaches only 6 inches in diameter and 4 inches in height. ‘Geisha’ (6” x 4”) has chartreuse leaves with a green margin. ‘Goody Goody’ has white leaves with a green margin and reaches 8 inches in diameter by only 2 inches high. ‘Bobbin’, a dwarf form of ‘Silver Kabitan’, is the smallest hosta in the “erect” group, with a diameter of about 4 inches and a height of only 2 inches. The “Tiny Group” of hostas includes ‘Abiqua Miniature’ (7” diameter x 3” high), ‘Blue Ice’(8” x 4”), ‘Gosan Gold Midget’ (5” x 3”)’, ‘Ivory Pixie’ (8” x 6”), ‘Shining Tot’ (6” x 2”), ‘Thumb Nail’ (4” x 2”), ‘Tiny Tears’ (4” x 2”) and ‘Tot Tot’ (8” x 4”).

‘Gold Colleen’ is a yellow-leaved form with striped purple flowers that only reaches 6 “ in diameter and 8” in height. ‘Golden Spades’ has a similar size and description. The Korean species Hosta venusta forms a dense, spreading mound reaching about 10 inches wide and but less than 3 inches high. ‘Blue Ice’ has the rippled blue leaves often found on giant hostas, but this time in a compact form only 10 inches wide by 6 inches high. Hosta ‘Little Bo Peep’ is a variegated, mounding hosta reaching just over 8 inches in width and 3 inches in height. ‘Cat’s Eyes’ has dark green margins and yellow centers that turn to ivory-white, growing to 6” wide and 2” tall.

Exceptionally large or small hostas can always be used as specimen plants, but they don’t have to be singled out. Tiny hostas can be used as rock garden plants, as edgers, or even in containers or trough gardens. Very large hostas can be used in perennial beds and borders, in large containers, or in some cases even as ground covers. The striking cultivar ‘Pineapple UpsideDown Cake’, for example, would make an ideal ground cover for semi-shade because it grows up to 50 inches in diameter but only reaches about 18 inches in height. The ripply cream-colored leaves have a very fine dark green variegation on the margins. Hosta ‘Rippling Waves’ is another good ground cover, with a mounding habit reaching 74 inches wide and 22 inches high. ‘Pewter Frost’ is a blue form suitable for ground cover, growing over 40 inches wide and 14” high. Hosta ‘American Halo’ features leaves variegated with dark blue green centers and yellow to cream margins, growing in a dense mound to about 72” wide and 22” high.


Both extremely large and extremely small hostas can make fascinating container specimens. Hosta grower Sandie Markland discussed planting hostas in containers in The Hosta Journal, a publication of the American Hosta Society (

“As many of us have learned the hard way, not all hostas are created equally. A hosta which performs beautifully in the Upper Midwest may prove a dismal failure in warmer climates. The same holds true when considering plants for container culture. With the notable exception of plants with Hosta sieboldiana and H. ‘Tokudama’ heritage, most hostas will do well in pots of appropriate size. H. sieboldiana, H. ‘Tokudama’ and many of their offspring may fare well in the short term, but my experience has shown a marked and sometimes rapid decline when kept in pots for more than a season or two.

“The container chosen for any given plant should be appropriate to the actual size of the plant, not its ultimate size. There should be no more than two to three inches of space between the outside wall of the pot and outermost roots of the plant. With more rapidly growing varieties, you may need to pot up each year, but it is well worth the effort in order to grow a strong and healthy specimen. Never plant a young, tiny plant in a large container. Chances are, it will languish and die."

Markland recommends retail potting mixes such as the brand names Jungle Growth, Lowe’s Professional Potting Mix and Sam’s Magic Earth (available at Wal*Mart), noting: “While slightly different in composition, all three have certain elements in common. they are low in both peat and perlite content, contain pine bark fines and other finely ground organic materials, are light to medium weight with good drainage and excellent moisture retention, and are inexpensive.

“Potting mixes heavy in peat should be avoided. Once the peat dries out, it is next to impossible to re-wet and, if you do manage to re-wet the mix, it remains soggy for quite some time. This is a real problem in winter. While perlite is useful in preventing compaction, it adds nothing else to the mix. It is far better to use something such as pine bark fines. They maintain space and, as they decompose, feed earthworms and beneficial microbes in the mix, which, in turn, feed your plant.”

In normal weather, Markland waters her potted hostas deeply once a week, twice if the weather is very hot and dry. “During my weekly watering, I fill each pot at least three times and let the water drain through the pot and out the bottom (always leave at least an inch or two of space between the soil line and the rim of the pot for this purpose). Watering in this manner serves two purposes. First, it ensures a thorough watering of the root zone and, second, it prevents the build-up of harmful salts in the soil.” 1

Carol Szalacha, a perennial specialist at Gethsemane Garden Center in Chicago, likes ‘Sum and Substance’ the best of the large hostas. “The foliage is a light apple green color, and it can get as high as four feet – it makes a good background plant. The leaves alone are the size of a small bar tray!

“Hosta sieboldiana ‘Elegans’ is another of my favorites – it makes a beautiful large clump, has white flowers and heavily corrugated blue leaves. Hostas with those heavily corrugated leaves are much more slug resistant thant others. In my own yard, one mature ‘Elegans’ hosta hides a tree stump, while others form a backdrop to a pond. Hostas are very drought –tolerant when established but they like water. Likewise, they will grow in almost any soil but they will thrive in composted soil or soil that is rich in organic material.

“Of the small hostas, ‘Pandora’s Box’ stands out. Its almost-round leaves are green with white trim. It grows to 6 inches tall and is a nice spreader – the plants in my yard almost doubled in size in one year. I think it spreads better than H. venusta.
‘Twist of Lime’ is another nice small one in two shades of green – a pretty light green and chartreuse. It has a traditional hosta leaf shape and grows to 8 – 10 inches high, filling in rapidly.

"‘Little Mouse Ears’ is a new one we just got in – I haven’t tried it yet in my own garden. It is sometimes hard for us to get the new or specialty hostas even though we do carry some expensive hostas. In a few years when the price goes down we should be able to get them.”



THE COLOR ENCYCLOPEDIA OF HOSTAS by Diana Grenfell and Michael Shadrack, 2004, Timber Press, Portland, OR

THE GENUS HOSTA by W. Georg Schmid, 1991, Timber Press, Portland, OR

American Hosta Society website:

American Hosta Growers Association website:

“The Genus Hosta, Chicago Style,” compiled by Rommy Lopat, The Weedpatch Gazette, Volume IV, No. 6, Summer 1996

Assorted retail mail order catalogues featuring new hosta cultivars

1“Shattering Some Myths About Hostas in Containers,” by Sandie Markland, The Hosta Journal, Volume 31, Number 1, Spring 2000

Monday, June 12, 2006

The Problem with Black Walnuts

First Published in The Landscape Contractor magazine

“What You Don’t Know About Walnuts Can Hurt Your Plants”

By Becke Davis

How many times have you planted perfectly healthy trees or shrubs into an existing landscape, only to have them die for no apparent reason? When that happens, do you call in a specialist from the County Extension Service you diagnose the cause of death? Do you have an arborist check out the remains of the plant? Or do you just bite the bullet and resign yourself to the inevitable loss of a few trees and shrubs? Nine times out of ten, you’d be safe to do that, but the 10th time you could be letting yourself in for a repeat performance.

There are a number of reasons why a relatively new plant can die -- planting too deeply (although that usually causes a slower death), herbicide contamination, insufficient watering, root burn from over-fertilization, rootballs sitting in water that won’t drain, and so on. When you are running down a checklist of possible reasons for the death of your plants, take a look at neighboring trees -- not just in your client’s yard, but in the yards of near neighbors, too. If you happen to see a black walnut (Juglans nigra) or a butternut (J. cinerea) growing nearby, that could be the source of your problem.

Black walnuts are valuable timber trees and they are relatively common in the Midwest. They can be found growing in the wild as well as in residential and commercial landscapes. The tree is hardy, the leaves are attractive, the roots help control soil erosion, and people don’t seem to mind the mess of falling walnuts. Black walnuts, butternuts and other walnut species that have been grafted onto the vigorous roots of black walnuts share a common trait: they produce a toxin called “juglone”, technically called 5-hydroxy-alphanapthaquinone. Other juglone-producing plants include shagbark hickory, mockernut hickory and the pecan. Juglone is called an “allelotoxin” and the reaction of plants to its presence in the soil is called “allelopathy”.

While some plants seem to be unaffected by the presence of juglone in the soil, other plants are highly susceptible to it. Even landscapers that are aware of the toxic properties of black walnut sometimes underestimate distance necessary to create a safe barrier for susceptible plants. Juglone is found in the the leaves, stems and branches, bark, buds, wood and primarily in the roots; some experts say it also appears in the nuts and hulls, while others insist it does not. In any case, juglone is not toxic to humans so eating walnuts carries no risk of poisoning. However, humans may suffer from allergic reactions when black walnut pollen is shed in late spring.

The fact that walnuts are fairly deep-rooted may protect some plants whose roots remain close to the soil surface. However, the roots extend in a very large radius around the tree, two to three times the radius of the crown. A young tree only 10 feet tall will have roots stretching out 20 feet or more. In a full-grown tree, the root zone can extend as far as 80 feet in diameter around the tree. Plant susceptible to juglone will be endangered anywhere within that root zone.

Experts disagree as to the risk of using sawdust or woodchips from walnut leaves, husks, branches or bark in the landscape, in mulch or even in the compost heap. While some insist that it is safe to do so, others say that applications of mulch, sawdust or compost containing any form of black walnut will eventually kill the treated plants. The presence of juglone in the soil has been traced both to living black walnut roots as well as decaying roots left in the soil from trees that have died and been removed. There are even reports of juglone entering the soil through raindrops coming off the leaves of black walnuts. Other reports say that adding nitrogen to the soil within the dripline of black walnuts can reduce the toxicity of the juglone.

Unfortunately, many reports -- coming from well-respected universities and other sources -- offer contradictory
advice, indicating that more research is needed in this area. Because of these mixed reports, using compost, mulch, shredded leaves or any landscape product containing live or decaying black walnut elements should be avoided.


The following is a partial list of plants that have been observed living within the toxic range of black walnut trees, rather than being specifically tested for juglone tolerance. Experts don’t all agree on these plants, which may be an indication that plants survive under certain conditions become more susceptible under others. In some cases, particular hybrids or species were tolerant, while others were not.

Arborvitae (Thuja spp.)
Astilbe (Astilbe spp.)
Bee Balm (Monarda didyma)
Begonia (Begonia spp.)
Black Locust (Robinia spp.)
Bleeding Heart (Dicentra spp.)
Bugleweed (Ajuga spp.)
Catalpa (Catalpa spp.)
Clematis (Clematis spp.)
Crocus (Crocus spp.)
Daphne (Daphne spp.)
Daylily (Hemerocallis spp.)
Elm (Ulmus spp.)
Euonymus (Euonymus spp.)
Forsythia (Forsythia spp.)
Hawthorn (Crataegus spp.)
Hemlock (Tsuga spp.)
Hickory (Carya spp.)
Honeysuckle (Lonicera spp. - most)
Japanese Maple (Acer japonica)
Juniper (Juniperus spp.)
Lamb’s Ears (Stachys spp.)
Maple (Acer spp. - most species)
Morning glory (Ipomoea spp.)
Oak (Quercus spp.)
Pachysandra (Pachysandra spp.)
Pansy (Viola spp.)
PawPaw (Asiminia spp.)
Redbud (Cercis spp.)
Siberian Iris (Iris siberica)
Sycamore (Platanus spp.)
Viburnum (Viburnum spp. - most)
Virginia Creeper (Parthenocissus quinquefolia)

Some reports list hostas, impatiens and ferns as being tolerant of juglone but the research on these is not complete. Crabapples and apples (Malus spp.) appear to have mixed reactions to juglone, since some experts list this species as tolerant, and others list it as extremely susceptible.
There are several reports of apple trees dying from the effects of juglone, though, so plant Malus specimens near walnuts at your own risk.


Basswood (Tilia heteropylla)
Blackberry (Rubus spp.)
Blueberry (Vaccinium corymbosum)
Chrysanthemum (Dendranthema spp. - some)
Cinquefoil (Potentilla spp.)
Daffodils (Narcissus hybrids and cultivars such as ‘King Alfred’ and ‘Ice Follies’)
Doublefile Viburnum (Viburnum plicatum var. tomentosum ‘Mariesii’)
Eastern White Pine (Pinus strobus)
European Alder (Alnus glutinosa)
Flowering Tobacco (Nicotiana spp.)
Hydrangea (Hydrangea spp.)
Lilac (Syringa spp.)
Lilies (Lilium spp. - especially Asian hybrids)
Mugo Pine (Pinus mugo)
Northern Hackberry (Celtis occidentalis)
Norway Spruce (Picea abies)
Ornamental Cabbage (Brassica oleracea)
Peony (Paeonia spp. - some)
Petunia species and cultivars (Petunia spp.)
Red Chokeberry (Aronia arbutifolia)
Red Pine (Pinus resinosa)
Rhododendrons and Azaleas (Rhododendron spp.)
Silver Maple (Acer saccharinum)
Tulip hybrids and cultivars (Tulipa spp. - some such as ‘Merry Widow’ and ‘West Point’)
Wild Columbine (Aquilegia canadensis)
White Birch (Betula spp.)
Yew (Taxus spp.)


“Black Walnut Toxicity to Plants, Humans and Horses,” by Richard C. Funt and Jane Martin, Ohio State University Extension Service Fact Sheet HYG-1148-93

“Walnut and Its Toxicity Explored,” by Tom Rood, Cornell University Cooperative Extension - Yates County, April 25, 2001,

“Walnut Trees and Your Garden: Effects of Juglone,” by Don Janssen, Extension Educator, University of Nebraska Cooperative Extension Service, Lincoln, Lancaster County, NE

“Black Walnut Allelotoxin Query: Plant & Pest Diagnostic Service,” PP&L Diagnostic Lab, Purdue University, West Lafayette, IN

Blue Roses

First published in The Landscape Contractor magazine

“Is Blue the Color of Money?”

By Becke Davis

Blue roses. Black tulips. The difficulty -- even impossibility -- of producing particular flower colors has not stopped botanists and plant propagators from making the attempt. This century has seen many horticultural advances, from increased disease-resistance to improved cold hardiness, from pest-resistance to drought tolerance -- and that is only the beginning.

Flowers are being bred to bloom longer, bloom repeatedly, and even to shed their spent flowers. Hybridizers seek the ideal form, the most sublime foliage, the most artful flowers and the most memorable fragrances. The holy grail, though, the pot of gold at the end of the rainbow that always seems out of reach, is exactly that -- the colors of the rainbow that are the most elusive are considered by many to be the ultimate unreachable prize.

Blue is one of the least common colors in the garden, and therefore one of the most sought after. Growers and hybridizers are quick to jump on the bandwagon whenever a new cultivar exhibits the least bit of blue coloration. Polarizing lenses and digital adjustments enhance catalog illustrations but the real thing often disappoints. Many flowers -- from blue lilacs to blue hyacinths to ‘Johnson’s Blue’ cranesbill geraniums -- have enough blue to merit the name, but often with enough lilac, lavender, purple, pink or other tints to keep the color from being an out-and-out “true blue.”

The color blue, in itself, is not the real issue, though -- rarity is. You want a true blue? It’s hard to find a flower much bluer than ‘Heavenly Blue’ morning glory. That excellent hybrid is so commonplace, though, that packs of seeds can be bought for a dollar or two in the produce department of the grocery store. Yet if anyone was able to develop a strong yellow morning glory -- a color not found in the genetic material of the genus Ipomoea -- demand for this easy-to-grow annual vine would surely skyrocket. On the other hand, yellow roses are ten-a-penny. But blue roses? The search for a truly blue rose -- just like the search for a truly black tulip -- is legendary.

GM, genetic manipulation, has resulted in many improved plant hybrids and cultivars, so it is not surprising that early color breakthroughs were related to this relatively young science. In 1991 an Australian biotechnology company called Calgene Pacific (later Florigene) announced that they had succeeded in isolating the gene that causes blue pigmentation in flowers. It was anticipated that this breakthrough would quickly be followed by the introduction of blue flowers where there had never been blues before.

The original plan to remove blue genes from flowers such as petunias and simply add the gene to the genetic material of the rose proved to work better in theory than in reality. Research sponsored by the American Rose Society has shown that rose coloration is determined by a range of two pigments (quercetin and kaempferol) to five pigments (carotenoids, cyanidin, pelargonidin, quercetin and kaempferol), with no trace of the blue pigment delphinidin. (1) Adding the blue pigment to the genetic material of a rose did not result in a blue rose because, as it turned out, isolating the “blue gene” was only part of the problem.

The blue pigment, delphinidin, is apparently only able to transfer its blue qualities to flowers whose petals feature alkaline cellular matter. Even when the pigment was directly applied to rose petal cells, the acidic nature of the cellular material inhibited the blue pigment and kept the rose from changing color.

The search for the alchemist’s stone -- the magic that will enable scientists to manipulate the form, foliage, colors and other features of a plant at will -- continues. Blue roses made news in the current issue of Discover magazine not because of years of genetic engineering research, but because of a fluke that may produce a novel route to the development of a blue rose. A few years ago, scientists at the Vanderbilt University School of Medicine in Tennessee and the University of Queensland in Australia accidentally discovered a human liver enzyme was spontaneously converting an amino acid found in a bacterial source into an indigo dye. This serendipitous discovery has since led the team of scientists, whose primary focus is researching disease-fighting drugs, into a sideline of using the enzyme/bacteria method to produce pigments that may one day turn flowers green, purple, red or brown -- and, of course, true blue.

If a blue rose is ever developed, it may turn out to be more of a boon for the cut flower industry than for the landscape industry. Florists already dye or spray roses, carnations and other flowers to dress them up for St. Patrick’s Day, to match prom dresses and bridesmaid’s gowns. Would a rose that is naturally blue make that much difference? In the April 2004 issue of Discover magazine, Marten Chrispeels, a plant geneticist at the University of California at San Diego, pondered the value of such a rose: “ ‘Would you be willing to pay $4 for a blue rose? Maybe for one, but not for 12,’ ” he observed. (2)

James Will, a senior lecturer in Horticulture and Plant Breeding at Burnley College, University of Melbourne, Australia, estimates that “a blue rose would be able to capture 5% of the international cut flower market -- a prize worth many millions of dollars annually.” (3) However, he goes on to point out that 70% of cut flower rose production now takes place in Third World countries where developers of a blue rose may have trouble collecting royalties. Certainly, to some extent research in the field of genetically manipulated pigments is dollar-driven, but there are many who would brush off such mundane concerns, raising the search for color rarities to an almost mystical level.

While blue roses and black tulips are probably the most famous (as yet) non-existent plants, they are not by any means the only color rarities in the plant world. In addition to roses, flowers missing “blue genes” include carnations, chrysanthemums, lilies and gerbera daisies (all of which are top-selling cut flowers), and the search continues for black orchids, red irises and white marigolds. As with roses that are called “blue,” some hybrids claim to fill the gap with these colors, too. For example, there are marigolds sold as “white” but they are closer to cream or ivory.

Florigene may not have succeeded in producing a blue rose, but in 1996 they did introduce the world’s first commercially produced transgenic flower, a carnation called ‘Moondust’. Although this and subsequent introductions have greatly expanded the range of mauve and purple carnations, scientists at Florigene and elsewhere have still not succeeded in their goal of producing a carnation that is distinctly blue.

On the other hand, genetic manipulation is resulting in some surprising horticultural developments. While there continues to be a lot of unease about genetically manipulated crops, there has been less concern about the use of GM in horticultural areas. These “smart plant” studies include research into potatoes as vaccines, creating transgenic plants containing a fluorescent protein designed as drought “early warning” sign, putting the fragrance back into modern roses, creating flowers that bloom in summer and again in winter, developing cut flowers that won’t wilt for weeks, even plants that can help detect the presence of land mines (land mines release an underground gas that causes the normally green plant foliage to turn red).

Blue roses may one day be the pot of gold to the floral industry, and there is bound to be a trickle-down effect on the landscape industry. But the real effect won’t be seen until such genetic manipulation is so commonplace that clients will be able to build “do-it-yourself” plants on their computers, just by running down a checklist and clicking on the features of their choice. Will such genetic manipulation change the face of flowers forever? Will we still be able to say “A rose is a rose is a rose” or will we find ourselves describing colors as either “hydrocarbons and their oxygenated derivatives” or “polyphenolic compounds containing 15 carbon atoms”?

In the language of flowers, white roses mean purity and innocence, pink roses mean admiration and happiness, yellow roses mean friendship and delight and red roses are a universal symbol of love. Lavender roses mean love at first sight, deep pink roses mean “thank you” and coral roses represent desire. To researchers today, blue roses represent the possibility of wealth and the achievement of science over nature. If they achieve their goal, who knows what blue roses might represent to future generations?



(1) “1980 American Rose Annual Pigments and Petal Colors,” and “Inheritance of Pigments,” by Lidwien A.M. Dubois, Institute for Horticultural Plant Breeding, Wageningen, The Netherlands

(2) “The Biology of Flowers: Roses are Blue, Violets are Red,” by Susan Freinkel, Discover magazine, April 2004

(3) “Quest for the Blue Rose,” interview with James Will, senior lecturer in Horticulture and Plant Breeding at Burnley College, University of Melbourne, Australia at Global Garden

“Towards a Blue Carnation,” by Roger Fox, Hydroponics, Casper Publications, Mar/April 1997, copyright updated 2002,

“Biotech Beauty,” InfoSource, Issue 87, September 2003, Published by Ag-West Biotech, Inc., SABIC (Saskatchewan Agricultural Biotechnology Information Centre), Saskatoon, Saskatchewan, Canada

Press Release: “Planned release of transgenic rose (Rosa x hybrida) containing kanamycin or chlorsulfuron resistance gene and ‘blue’ gene (flavonoid 3’5’ hydroxylase), August 8, 1994, Dr. Stephen F. Chandler, Florigene Pty. Ltd., Collingwood, Victoria, Australia

“Brave New Rose,” by David Concar, October 31, 1998, New Scientist, England,

“Clever Carnations,” by Dr. Edwina Cornish, Managing Director, Florigene PTY. Ltd.,

“In Pursuit of Blue, Sweeter-Smelling Roses,” by Paul Elias, Associated Press, published in the Chicago Tribune on November 22, 2002

“What Rose Colors Mean,” by Dan Vierria, February 14, 2004, International Cut Flower Growers Association,

“Plants to Uncover Landmines,” by Laura Nelson, January 29, 2004, Aresa Biodetection/Nature News Service, Macmillan Magazines Ltd., 2004,

“What Flower is That?,” by Stirling Macoboy, Portland House, NY, 1988

“What Flower Glows in the Dark?,” by Chelsea Vandaveer, October 24, 2002, Weird Plants Newsletter,

“Evening Primrose,” by Mary Beth Zeitz, (ibid)

“Applications of Genetic Engineering in the Green Industry,” by Pablo Jourdan, Department of Horticulture and Crop Science, Ohio State University

“Biotechnology in the Garden,” by Claire Granger, Biologist, June 2001, Information Systems for Biotechnology newsletter