Thursday, April 4, 2013

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A Visit with Knock Out Roses' William Radler

William Radler
William Radler in his living room
There was snow on the ground outside, but plenty of blooms inside the home of William Radler, developer of the popular Knock Out® shrub roses, when I visited recently.
Botanical drawings of roses lined the living room walls. A bouquet of silk roses sat on a table. There was a rose inlay on the wooden floor. And in the basement, the real deal – row after row of rose seedlings, many of them in full flower, under fluorescent lights.

This is the rosarium or “greenhouse” where Radler is developing his next generation of roses. Only the best will ever make it to market. Some may even be good enough to become Knock Out® roses, which are noted for their disease resistance.
More than 80 million Knock Out® roses have been sold since the first was introduced in 2000, making it the best selling rose series in the U.S. It’s also becoming more popular overseas, especially in Europe, Australia and Japan. Two of the seven varieties have been chosen as All America Rose Selections.

With such overwhelming success, you might expect that Radler, now 70, would be slowing down or at least would have moved his rose breeding operation to a larger, more high tech facility. If so, you’d be wrong on both counts.

Radler is planning to step up his rose introductions from one or two a year to as many as five. He especially wants to expand beyond the shrub and climbing roses in his portfolio.

The goal? “I want everything,” said Radler. He hopes to have so many rose varieties that it will require a separate catalog to list them all.
“Everybody hears about the Knock Outs®,” Radler said. “They don’t realize I have 27 roses in production. They might not all be Knock Outs® but most of them are low maintenance roses, the kind of roses people are looking to put in their gardens.”

Pink single rose with yellow eye
Brite Eyes, a Radler climbing rose
Photo courtesy of The Conard-Pyle Co./Star Roses and Plants

Eventually, he wants to produce low-maintenance hybrid teas, floribundas, miniatures and polyanthas. Radler’s particularly hot on miniature roses at this point.

“Everyone’s got a place for a miniature rose,” he said. “If they were black spot resistant, I think more people would plant them.”

The success of Knock Outs® has sparked its share of criticism in rose circles. Some rose fans feel that Knock Outs® are pushing other worthy rose varieties out of the market. Others complain that his most popular roses aren’t fragrant.
Radler countered that Knock Outs® are shrub roses, not exhibition roses which often require extensive spraying and care. People no longer have the time or inclination to fuss with roses in their garden, he said. Low-maintenance shrub roses like his often fit the bill.

He also noted fragrance is somewhat subjective, with some people able to detect a fragrance while someone else can not. Radler said the original Knock Out® has a fragrance and that Milwaukee’s Calatrava, a white shrub rose he developed, “can compete with any other rose on the market for fragrance.”
Shrub roses, he added, are not usually introduced for their fragrance.

“There’s all the David Austins, but they don’t make good shrub roses,” he said. “At the end of the season, they’re either the Eiffel Tower or they’re flopping all over the place.”

Radler with rose seedlings
In the basement with the latest crop of rose seedlings
Rose seedlings in bloom
Flowers galore
Radler has been hooked on roses ever since he bought his first one at age 9. He was winning prizes for his roses while still in college, perhaps one of the reasons why he switched to landscape architecture after only one semester as an art major. He has been breeding roses since the mid 1970s.

His growing set-up remains low tech: saw horses, 2x4s, shop lights and recycled Styrofoam slabs. Meticulous details about each seedling are kept on index cards off to one side.

At this stage, he cautioned, it’s not always possible to tell which roses will perform the best in the garden.

“The miniatures grow larger under the fluorescent lights than they do in the garden,” he said. “And the regular ones grow smaller under the lights than in the garden.”

Flower color also can be more intense outside than under the lights, he added.

Baby rose seedlings
Newborn rose seedlings under the lights

Not all of Radler’s crosses work of course. During a recent visit, he showed me a rose with buds that have never opened and a yellow rose with a green, grassy center.

On the other hand, there was a white rose with a fragrance to rival any at a high-end perfume counter. There also was one with a single layer of purple (yes, purple) petals held straight up at a 90 degree angle as well as several interesting color combinations.
These 500 seedlings will eventually be acclimated to sunlight and join the approximately 1,600 roses outside on his 2-acre lot. They won’t be coddled in any way, but assaulted with numerous enemies including overhead watering and black spot. Lackluster performers are culled. Those that flourish are sent off for six years of field trials and may eventually be marketed by The Conard-Pyle Co./Star Roses and Plants.

Yellow rose seedling
A very delicate bloom

Vermillion rose seedling
What would you call this color? Vermilion?

Apricot and yellow rose seedling
Loved the color combination on this seedling

This rose was especially fragrant

Pink striped rose seedling
Striped petals anyone?
Radler, a life-long Milwaukee resident, said he has no plans to move anywhere else. His first job after college was with the Milwaukee County parks department. He eventually went on to serve as garden director of the nearby Boerner Botanical Gardens from 1981 until his retirement in 1994.

“People who need to get away…I don’t understand that. I like to be in one place and have everything that I need in one location,” he said. “I could easily afford a place in Door County or a place in Palm Springs but that means I’m away from here.”

Success has resulted in some changes at the “headquarters” of Rose Innovations LLC, however. He used to do all the work himself but now has a staff of 8 people. He also has remodeled his house. One of those changes was to add a one-car garage because the original two-car garage is overflowing with garden supplies.

Radler's sunroom filled with plans
The sun room

Lest you think Radler is a plant snob, he does have many other plants besides roses. A two-story sun room holds everything from African violets and cactuses to lush tropicals. An extensive perennial garden in the front yard has every plant labeled with its common and botanical name.

He is introducing his second perennial this year, Amethyst Kiss™ spiderwort (Tradescantia ‘Radtrad’) which has larger flowers, larger flower clusters and flowers that are more blue that other varieties. He had previously introduced Sweet Thing™ verbena (Verbena ‘Radverb’).

Radler's snow-covered back yard
The back yard
One of his upcoming projects will be to put prairie grasses and plants on the tall berm just behind his property. It was formerly used by one of the Milwaukee's interurban railways but is now abandoned. He said the utility that owns the land has just given him permission for the project to go ahead.

Another, possibly even bigger project involves breeding tropical fish and gold fish. He has added several large tanks throughout his house over the past three years.
“My goal is to create tropical fish and goldfish that the world hasn’t seen before,” Radler said.

Does he have any names in mind for these new fish? Perhaps something like Knock Out, I asked?

He pondered the question for a minute and just smiled.

By Karen Geisler


  1. Very nice post. I have not planted Knock-Outs, but consider them a very valuable option, especially because they are lower maintenance. Fragrance in roses is very important to me, and there are fragrant shrub roses such as my beloved Sally Holmes, which needs very little coddling.

    1. Thanks. I hope your Sally Holmes survives the rabbit damage. It's a pretty tough rose so I bet it will.

  2. Great interview, Karen! That peach/yellow bloom is gorgeous. I think I need your advice about Roses. I'm a huge fan, but I don't use systemics so the Knock-Outs might be a good choice for me. I currently have only two types of Roses growing in my garden--one was crossed by my great-grandfather, and the other was in the garden when I moved here. I'm thinking about adding a climbing Rose, but it has to be hardy to zone 4 or 5. Any suggestions?

    1. You could try Winner's Circle, a Radler rose with nice red flowers, or Brite Eyes. I also had good luck with William Baffin, a Canadian climber, when I lived in St. Paul. It's hardy to Zone 3.

  3. Heather SchusterApril 8, 2013 at 6:40 AM

    Terrific article and terrific photos! I know Will Radler well, and I'm impressed with what a nice job you did covering his love of plants, and his meticulous scientific methods. I can't wait for my Knock Outs to bloom....

    1. Thanks! He's a fascinating individual. Can't wait to see what he comes up with next...

  4. So glad I came upon this interview! The Knock Out rose was my choice when I helped design a restoration of a public garden here in our town, and the long hedge of them has never let me down! Because of it, many more have planted in gardens - the visitors love it! Getting an inside look at the man responsible was interesting!

  5. Does the knock out rose need dead-heading ? Or can I just plant them and watering is all they need besides a little fertilizer now and then ?

  6. My knockouts have the dreaded rose disease and is there anything to be done or should I just toss them. Are there copy cat varieties which are inferior?

  7. I lost a Knock Out® to 'Rose Rosette Disease' last year. Everything I read advised digging it up and disposing of it safely so as not to spread the RRD. I dug mine up..placed it in a large plastic yard bag..and took it to the landfill. The bag eliminated spreading RRD enroute to the landfill but wasn't necessary when I dumped it.

  8. I now have 53 roses and 48 of them are Radler hybrids. My Knockouts have inspired other gardeners in my tiny town to plant more roses in their own yards...and I am loving it.

  9. I now have 53 roses and 48 of them are Radler hybrids. My Knockouts have inspired other gardeners in my tiny town to plant more roses in their own yards...and I am loving it.

  10. I really enjoyed reading this post. I don't Love knockouts for my own garden because I'm partial to fragrance, but they are indispensable for landscape color and I love seeing them around.

  11. I really enjoyed reading this post. I don't Love knockouts for my own garden because I'm partial to fragrance, but they are indispensable for landscape color and I love seeing them around.

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