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The Historical Significance of ‘Knock Out’

by ARS past president Pat Shanley

Reprinted from “The Sustainable Rose Garden – A Reader in Rose Culture”

'Double Knock Out' from Star Roses and Plants

In 2000 a rose was hybridized, by William J. Radler that would succeed in transforming the image of the rose from a fussy Prima Dona to a friendly garden plant. That rose was ‘Knock Out’. For years, roses have had the reputation of being high maintenance plants and indeed they were, for the hybridizers had given the rose loving public what they craved and that was hybrid teas bred for their exhibition form. Regular spray programs were the norm and no one thought too much about the consequences of using these caustic chemicals. One by one, governments, worldwide are banning the use of environmentally harmful chemicals and the day is fast approaching when we will no longer be able to use them in our gardens.

The advent of ‘Knock Out’ changed how people garden with roses, for it is disease resistant, specifically black spot resistant. When I started growing roses, over 20 years ago, my first rose bushes were four Hybrid Teas – ‘Sterling Silver’, ‘Tropicana’, ‘John F Kennedy’ and ‘Fragrant Cloud’. I knew absolutely nothing about growing roses. I planted, watered, and fertilized them. They leafed out and produced a few blooms that first June. Then came the heat and humidity of a New York summer and with it black spot. I watched them loose their leaves and desperately sought a solution. I was horrified when I discovered the solution was spraying caustic fungicides every 7-10 days. Imagine how unpleasant it is to don long sleeves, long pants, socks, shoes, a hat, goggles and rubber gloves for spray protection – in 90 degree heat and 95% humidity! I sprayed early in the day to avoid the extreme temperatures, but it was still a miserable experience. ABOVE: 'Blushing Knock Out' from Star Roses and Plants

How many people had similar experiences and said, “Forget it! I’ll grow something else?” So, we watched the decline in popularity of the rose with a heavy heart. I used to dream of how wonderful it would be if roses didn’t get black spot and would never need to be sprayed. Then came “Knock Out” and for me it was a dream come true! ABOVE: 'Blushing Knock Out' by Rich Baer

The advent of ‘Knock Out’ is a watershed event that the world has not witnessed since the ‘Peace’ rose was introduced in 1945 and before that ‘La France’ in 1867. It changed the benchmark against how roses are judged by the general public and it changed how people garden with roses. From a technical standpoint, a rose of this degree of maintenance free growing had not been seen before. It needs no spraying, and no dead heading to rebloom. It is hardy to Zone 5 and crown hardy to Zone 5A and blooms from May through November in the Northeast. These characteristics have made it the most dominant plant in the industry. It is used commercially, as well as residentially and can be seen in strip malls, and corporate campuses where consistent color and foliage are a must. One can safely say that ‘Knock Out’ has promoted the visibility of roses. They are everywhere and shouldn’t a great plant be in a lot of places? ‘Knock Out’ is a rose that anyone can grow. It has become a staple in gardening and a way to draw the public back into our wonderful hobby. Once hooked on roses, the next step would naturally be to grow other types of roses.

The historical significance of ‘Knock Out’, is far reaching. It has set the bar for hybridizers worldwide. It is currently being used in breeding programs around the world including France, Germany, the UK and Asia – specifically Japan. We have seen a return to growing roses, their incorporation into the landscape as a part of the garden and a return to growth in membership for our local and national societies. ABOVE: 'Knock Out' from Star Roses and Plants

One hundred years from now the rose world will look back on ‘Knock Out’ as one of the most significant developments in the evolution of roses and sustainability. Will Radler tells the story of ‘Knock Out’ and how he planted hundreds of seeds that year and only one germinated. That one seedling was ‘Knock Out’. When asked why he thought this phenomenon occurred then, he answered, “Because the world needed it.” The prosperity of ‘Knock Out’ benefits all of us, the rose growers, the rose societies, the nurserymen and the botanical gardens in renewing interest in growing roses. In this day of “Green” thinking, it gives credence to growing roses that fit into the landscape without having to destroy the environment to do so. There are many more disease resistant roses coming from the hybridizers, worldwide, and that can only help us more.

According to Will Radler, the hybridizers of today are working towards the day when roses will no longer be something that only “rose people” can grow. “Roses won’t have all the special needs anymore. The hybrid teas of the future will no longer be a “Totem pole” plant, but a full plant with ample stems, shorter than the long stem roses of today. It will not require dead heading or heavy fertilization to rebloom. Work is being done to breed roses for midge resistance, Japanese beetle resistance and late spring frost tolerance.” Within the ‘Knock Out’ family of roses, ‘Sunny Knock Out’ is showing excellent resistance to midge. The hybridizers are also working hard to incorporate fragrance with disease and pest resistance, for who doesn’t love a beautiful fragrant rose? In essence we will be able to have our cake and eat it too. ABOVE: 'Knock Out' by Rich Baer

Interest in exhibiting roses has also suffered with the decline in popularity of the rose. ‘Knock Out’ has generated a renewed interest in the shrub rose class, however hybrid teas are what serious exhibitors care about. The hybrid teas of the future will hopefully be plants with good disease resistance…fuller plants, with shorter stems. When this comes about, the American Rose Society may need to reexamine the judging standards for showing roses. But I see that as a good thing as well, as it will help to renew interest in rose shows, which benefit our hobby by educating the public on the joys of growing roses. ABOVE: 'Blushing Knock Out' by Rich Baer

People no longer wish to spray chemicals to grow a beautiful garden. Roses, including hybrid teas, that can produce a gorgeous healthy bush, that is attractive, with or without blooms, will be a wonderful addition to any garden and the hybridizers are working on this as we speak. Disease resistant, “Queen of Show” hybrid teas will be more popular to grow and that could very well further the revival of membership in our societies, both local and national. It will renew interest in exhibiting roses, which will lead to increased sales and the success of the nurserymen. All this from the coming of a rose that anyone can grow and that rose is ‘Knock Out’. ABOVE: 'Rainbow Knock Out' from Star Roses and Plants


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