Flack Lilac Collection


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I.    Nostalgia
II.   A Little Background
III.  Collection History
IV.  Landscaping With Lilacs -species, bloom sequence, size, cultural needs
V.   Care and Maintenance -pruning, fertilizer,etc.
VI.  Resources - in print and online, ILS, local collections


I. Lilacs and Nostalgia

April is the cruelest month, breeding
Lilacs out of the dead land, mixing
Memory and desire, stirring
Dull roots with spring rain.

T.S. Eliot The Waste Land, 1922

When lilacs last in the dooryard bloom'd,
And the great star early droop'd in the western sky in the night,
I mourn'd, and yet shall mourn with ever-returning spring.

In the dooryard fronting an old farm-house near the white-wash'd palings,
Stands the lilac-bush tall-growing with heart-shaped leaves of rich green,
With many a pointed blossom rising delicate, with the perfume strong I love,
With every leaf a miracle-and from this bush in the dooryard,
With delicate-color'd blossoms and heart-shaped leaves of rich green,
A sprig with its flower I break.

Walt Whitman When Lilacs Last in the Dooryard Bloom'd
In Leaves of Grass, 1867

What is it about lilacs?
When I have given tours of the Flack Lilac collectionin Maxwell Arboretum and begin by talking about the strange pang of memory that so many people associate with lilacs, invariably the tour participants nod and smile. They too are caught up in recalling lost days of childhood, grandma's lilacs on the farm, the shrub their mother carefully tended outside the back door. They get a smile of recognition on their faces. We all know what I'm talking about. Everyone has a lilac story. My own stems from growing up in an old farmhouse on what was then the edge of town. We would make May baskets and fill them with grape hyacinths, candy, and lilacs blossoms from the large overgrown yet prolifically blooming stand in the backyard. Picking the lilacs for the May baskets, we were enveloped by the overwhelming scent-the scent that everyone is remembering as I talk about lilacs and nostalgia. The shrubs were covered in monarch butterflies, migrating north, and we loved seeing them. Our baskets were deposited on the doorsteps of our childhood friends, the doorbell rung, and we hightailed it out of there, lest the door be answered and we be chased and caught; for which the price to be paid was a kiss. Do kids still make and deliver May baskets? (top⇑)

II. A Little Background

A member of the Oleaceae or Olive family, the genus Syringa, lilacs, is made up of around 23 species (I say around because taxonomists continue to refine and rearrange specific assignations) and countless cultivars. The name Syringa is derived from the Greek syrinx meaning "hollow stem." It refers to the nymph Syrinx who was turned into a hollow-stemmed reed by the god Pan who then fashioned the reed into his first set of pan-pipes.

Two lilac species are native to eastern Europe, where they were first cultivated at least as early as the 16th century-probably much earlier in Turkey. These are the common lilac, Syringa vulgaris and the so-called Hungarian lilac, Syringa josikaea. All other lilac species originate in Asia (China, Japan, India, and Korea) and were introduced to the west by plant explorers primarily in the late 19th century. They were brought to America in the 1600s by the earliest Dutch settlers. Both Thomas Jefferson and George Washington recorded the planting of lilacs on their estates. (top⇑)

III. The Collection Historylilac2.jpg

Soon after becoming Director of the University of Nebraska-Lincoln's Grounds Department, Bud Dasenbrock began to formulate plans for a Lilac Collection. In 1981, Dasenbrock utilized a donation from Lola Flack given to memorialize her husband Milton to begin the collection that you see in Maxwell Arboretum today. He gathered suggestions for what lilacs to obtain to start the collection and plants were obtained and held in the nursery for a year while they put on a little growth. Plants were bought at the International Lilac Conference auction that was held in Des Moines that year as well as from commercial nurseries. In December, Dasenbrock asked Campus Landscape Architect Kim Todd to develop a design for the collection on the south side of C.Y. Thompson Library (now the Dinsdale Family Learning Commons) and planting was begun in the spring.

Many prominent Nebraska lilac experts have had an impact on the collection. Max and Darlene Peterson have one the largest private collections in the world at their farm, Meadowlark Hill, near Ogallala. In addition to collecting and growing lilacs, the Petersons are breeders who have introduced a number of acclaimed cultivars to the trade. From the beginning, Max had helped Dasenbrock with a list of what lilacs to start off with and offered to donate any of the plants needed. Later, Max helped me assess the collection when he was visiting Lincoln in 2004. He is currently U.S. Plains Regional Vice President of the International Lilac Society.

Max and Darlene Peterson at the Flack Lilac Collection, April 2004


Lourene Wishart of Lincoln was the Vice President of the Midwest Chapter of the International Lilac Society for many years and grew numerous species and cultivars both at her home in Lincoln and at the farm she owned with her husband at Bennet, Nebraska, called the Lilac Farm. (Earl Maxwell visited Lilac Farm with UNL Botany Professor Raymond J. Pool in 1955 and recorded a list of native plants they founded growing there.) In 1990, Landscape Services Nursery Supervisor Maggie Broberg McVicker took air layer grafts and root suckers of lilacs from the Wishart house in Lincoln before it was sold. Some of these lilacs can still be found in the department nurseries; other plants collected at the time have been planted on campus (notably a rhododendron in the arboretum collection). On November 12, 1980, Mrs. Wishart wrote to Dasenbrock, "It's my great pleasure to assist you in your lilac color choice for the UN campus, or any planting you may be interested in. Remember I am a 100% FAN for the Professor Maxwell project and Arboretum!" Lourene Wishart received the Honor and Achievement Award from the International Lilac Society in 1978.
Both of the Petersons and Lourene Wishart have lilac cultivars named for them.

Finally, there are Jacob and Hans Peter Sass, noted Nebraska plant breeders during the first half of the 20th century. The Sass brothers are often remembered for their award winning iris hybrids, but they also worked with peonies, daylilies, poppies, and gladiolus as well as lilacs.

Dasenbrock first heard of the Sass lilacs in 1981 from Max Peterson who grew them all and offered suckers. Peterson's Sass lilacs still grow in the department nurseries. Dasenbrock embarked on a decade long search for more information on the brothers. In 1995, Cyril Bish, UNL County Extension Agent, Nebraska Nut Grower, and longtime member of the Friends of Maxwell Arboretum, donated another Sass lilac, 'Woodland Violet' to the department. In 2004, I showed Mr. Peterson these plants. One of the Sass lilacs grows in the Flack collection—'Snow Showers.'

Hans Peter Sass (the man on the left may be William Dunham, the landscaper of the "Farm Campus" in the early years of the 20th century)

Lola Flack herself was honored by a gift to the collection in her name by Augusta Lux. This donation was put toward the 'Donald Wyman' grouping at the southwest corner of the collection.

Over the years the identification of some of the lilacs was lost, especially when the Jeanne Vierk Yeutter Garden was built and the installation of new sidewalks necessitated the relocation of some of the lilacs in the collection. Since then, a lot of work has been done to identify the unknown lilacs and most of them were. A few lilacs in the collection remain unidentified. While it is not common practice for a Botanic Garden to retain unknown specimens, the beauty of these few plants made it seem more than a little absurd to remove them. (top⇑)


IV. Lilacs in the Landscape

Lilacs are a much more versatile shrub than many people realize. In size, bloom color, bloom time, and scent they can range from 3 to over 12 feet, from white to deep magenta, from late April to late May, from the well-known lilac fragrance to almost spicy. You can use lilacs as single specimen plants, screens and hedges, in masses, even in the perennial border. Make sure you match the species or cultivar to the site; you don't want to be continually having to prune your shrubs in order for them to fit in the space you've allotted them. Keep in mind the bloom color: certain purples or magenta may not look good against red brick walls. And don't forget that some lilacs have nice fall color.

Bloom Sequence of Syringa Species:

Early: hyacinthiflora
Mid: meyeri, vulgaris and its "French Hybrids," ×chinensis, patula
Late: villosa, prestoniae, reflexa
Very Late: reticulata (Japanese Tree Lilac)


V. Care and Maintenance

Lilacs are relatively easy to grow, that's why you can find them still thriving, albeit overgrown, at old farmsteads a century later. They love Nebraska. They like the cold winters and can handle the heat. If rainfall is inadequate to the point of leaves drooping, supplemental irrigation is helpful to maintain the plant's vigor. High humidity causes some plants to get a bit of powdery mildew at the end of the season, unsightly but not damaging. They can handle our clay soils but, like many plants, appreciate if you prepare the soil before planting with organic matter, i.e. compost.

If people ask, "Why don't my lilacs bloom?" it's usually it's due to one or more of the following:

1. Insufficient sun: Lilacs need a minimum of 6 hours of sunlight a day. The more, the better. If you can site shrub to get sun all day, it will reward you.
2. Too much nitrogen fertilizer: When I managed the Flack Collection, the simplest thing I did that had the biggest effect was simply to keep the turf fertilizer away from the root zone. Excess nitrogen encourages vegetative growth at the expense of blossoms.
3. Improper pruning: Lilacs bloom on the previous years's growth. If you prune your lilac (especially unnecessary shaping) in the late winter/early spring, you'll be pruning off its flower buds. See pruning below.

Lilac Pruning:

If you are starting from an established but young shrub, simply prune out 1/3 of the largest oldest canes close to ground level every year. This will insure the growth of new canes and keep the lilac blossoms at nose level.
Often, people are faced with overgrown neglected lilac shrubs full of large old trunks and blossoms only at the very top, often above one's head. Such plants need rejuvenation. With lilacs there are three basic ways to do this:

1. Begin a three year rotation of removing 1/3 of the largest stems every year. Theoretically, at the fourth year, you'll have an entirely new plant.
2. Cut the entire shrub down to close to ground level-2-6". New growth will emerge and in a few years your plant will be a good size and blooming again.
3. Remove the oldest stems, some or all depending on your particular plant, and cut the remaining ones to about 18". New growth will emerge from these stumps and you'll see bloom in two years, maybe even a little the year after pruning.

In rejuvenating the entire collection, I treated it as one would a single shrub. Instead of removing one third of the canes each year, I decided to rejuvenate 1/3 of the collection each year. That way, there would still be adequate bloom on the unaffected shrubs each year. In addition, I experimented by trying each of the three pruning techniques described above on different groups of lilacs. I was surprised to find such good results so quickly after cutting plants down to 18". Although every plant is different and poses its own unique problems, I would probably use that technique again in the future. You can tell which plants got this kind of pruning in 2005 and 2006 and see what you think.

  Lilac Pruning 1 year

Lilac Pruning 1 year

Lilac Shrubs One Year After Being Pruned to 18"  





Same Shrub as Above
After Two Years
Great Bloom After Only
Two Years of Being Cut to the Ground

What about removing old seed heads?

For a long time there has been a recommendation by some to remove old blossoms after the lilac has finished flowering. This was put forth on the same principal that we deadhead herbaceous plants-so that energy is put into producing new flower buds not maturing seeds. Others-including many lilac experts-feel there is no difference in bloom when spent blossoms are removed. The height and number of plants in the Flack Lilac collections makes removing spent blossoms prohibitive and we don't seem to have a problem with bloom. If you have only a few reasonably sized plants you might consider removing the old blossoms if you find them unsightly. And who knows-maybe it will affect your plants flowering.

Insect problems:

Scale: These small hard-shelled insects suck sap from lilac stems and can cause damage if the infestation is large. They can be controlled with horticultural oils applied at the crawler stage.
Scale has been only a minor problem from time to time in the Flack Lilac Collection.
Borers: It is important to accurately identify any insect pests before choosing a treatment. Lilac borers can sometimes be a problem, but can often be dealt with simple by removing and destroying the affected limbs. If you are willing to use insecticides and the infestation warrants their use, timing of applications is critical. Don't waste your time and money or negatively impact the environment by misapplying insecticides.
Ash/Lilac Borers: Spray trunk and limbs during adult egg laying, early to mid May.
Privet Borers: Treat in early May with additional applications in mid May and early June. Spray canes/stems to point of runoff.
Suggested Products: bifenthrin, permethrin
Apply insecticides to point of runoff. Multiple applications may be necessary.


Lilacs are really pretty drought tolerant. Depending on your own feelings about water use, you may want to give your lilacs supplemental irrigation in the summer for best growth and performance.


Remember, keep your turf fertilizer away from the lilac's root zone! You can incorporate a high phosphorus fertilizer, but in general lilacs do pretty well on their own.

VI. Resources

Fiala, Fr. John L. Lilacs: The Genus Syringa. Portland, Oregon: Timber Press, 1988. Paperback, 2002.
This is the lilac bible. Lilac master Fiala covers all areas of the genus: taxononomy, history, culture, landscaping, pests, propagation, and more. He makes numerous recommendations of the best cultivars in each color class and has a great writing style, continually referring to the reader as "bon jardinier" or "mon ami." Fiala provides a lot of information on the great lilac breeders and the book's back matter is packed with information. Bountiful color photographs complement the volume. If you buy one lilac book, this should be it. A new edition, revised and expanded by the international lilac registrar, Freek Vrugtman, will be published by Timber Press in August 2008. The new edition, among other things, covers recent introductions from Poland and Russia and has over 500 new color photographs. CLICK HERE FOR MY REVIEW OF THE NEW EDITION

McKelvey, Susan Delano. The Lilac, A Monograph. New York: The Macmillan Company, 1928.
One of McKelvey's two magnum opus (the other is Botanical Exploration of the Trans-Mississippi West), this was the lilac book until the publication of Fiala's some 60 years later. The bulk of the text is 500 pages discussing every known lilac species and cultivar; it is exhaustive. McKelvey examines in detail the literature on lilacs. There are also short chapters on culture, propagation and pruning, forcing, and insect pests. Unfortunately the numerous photographs are all black and white. I love this book. It is an exercise in obsessive compulsion and is written in a beautiful style from another time. You can sometimes find this book through antiquarian book dealers but be prepared to spend $200. C.Y. T. Library on UNL's East Campus has a copy.

Wister, John C. Lilac Culture: Its History, Growth and Propagation. New York: Orange Judd Publishing Company,1930.
A nice little volume by the creator of the lilac color code and noted American horticulturist. In 1943, Wister also published Lilacs for America.

Harding, Alice. Lilacs in My Garden: A Practical Handbook for Amateurs. New York: The Macmillan Company, 1933.
Alice Harding received the prestigious Mérite Agricole from the French government-putting her in such disparate company as Louis Pasteur and Catherine Deneuve. Introduced by no less a personage than the son of famed French breeder Victor Lemoine, Emile Lemoine, this volume is Harding's love song to lilacs.

Vrugtman, Freek. International Register of Cultivar Names. Hamilton, Ontario: Royal Botanical Gardens., 1997.
The RBG is the International Cultivar Registration Authority (ICRA) for the genus Syringa. This volume is current to 1997 and subsequent cultivar registrations are published in the journal HortScience. An up-to-date version of The International Register and Checklist of Cultivar Names in the Genus SyringaL. can now be accessed and downloaded from this site:

Organizations and Web Resources:

International Lilac Society
Anyone with an interest in lilacs should join the International Lilac Society. They are a great bunch of people ranging from lilac "fanciers," to serious collectors, to internationally known breeders. With chapters all over the world, the Society keeps up with everything including the great Russian introductions. Membership is reasonable and you get the quarterly publication. I was fortunate to attend their convention in 2004 at the Lied Lodge in Nebraska City and had a wonderful time being in the presence of so many passionate lilac lovers.

The Lilac Story: Past and Present
This is a great site produced by Canada's Digital Collections and the Royal Botanical Gardens. Packed with a lot of information on all aspects of lilacs, it has especially good material on breeders focusing on Canadian Isabella Preston. (If you haven't ever looked over Canada's Digital Collection's, it's a wonderful thing.)

NOS Syringa Page
This is a page from the amazing New Ornamentals Society web site.