Knock Out roses are ridiculously disease resistant.
Knock Out roses are also easy to grow, cold hardy to zone 4, remontant, and have nice flowers. More than 80 million Knock Out roses have been sold since their introduction in 2000. Here is a list of some other disease resistant roses.
Casual gardeners love Knock Out roses, and I understand. Landscapers, notorious for limiting their plant selections to can’t miss varieties, plant Knock Out roses in mass in commercial settings. You can find Knock Out roses at Walmart, both in the garden section and planted in the parking lot islands. Supposed brown-thumb gardeners everywhere can now successfully grow roses. Knock Out roses are not so popular with the elite of the rose gardening world…the rosarians.
Knock Out roses are not generally fragrant, I’ll give you that. Individual flowers are a little relaxed in nature, but the same can be said for the greatest climbing rose ever, New Dawn. I can think of no other criticism of Knock Out roses except for their ubiquity in the landscape. Is such criticism short-sighted?
Rose aficionados are not generally fans of Knock Out roses, but how can any reasonable rosarian not have respect? Knock Out roses provide an answer to almost every complaint about modern garden roses, and maybe herein lies the fault finding. Both orchids and roses have a reputation for being a challenge to grow. Thus, there is cachet in growing beautiful orchids or roses. What happens when a rose anyone can grow becomes available?
Say what you want (and plenty has been said) about the Knock Out rose series, but the following is inescapable: There has never been a more commercially successful and easy to grow ever-blooming rose available to gardeners.
More thoughts on the subject of rose gardening are outlined here.
Old roses are wonderful. Most modern roses were awful. This is changing as robust varieties such as the Knock Outs roses are introduced.
Many of the old roses are strong growers and disease resistant, with shrub forms that are mouth-watering. Most of these old roses bloom once a season, in spring. The old China roses are remontant, blooming throughout the entire growing season. Modern roses bred during the latter half of the 20th century were generally terrible garden plants, ungainly and disease-ridden.
If Knock Out roses are worthy of a place in the garden, this is no attack on the special nature of many of the old roses. Frankly, most of the hybrid teas and grandifloras of the last century, with the possible exception of the majestic Queen Elizabeth, can go straight to the dustbin of history.
Spraying everything in the garden for a few flowers has got to stop. Whether you appreciate them or not, Knock Out roses show us the potential of rose gardening.
Late 20th century rose breeders and the American Rose Society did us very few favors
Rose breeders (Jackson & Perkins being at the forefront) of the mid-1950’s onward largely failed in attempts to give Americans the healthy long-stemmed high-centered roses we associate with romance, love, and the florist shop. Sure, you might get a measly bloom here and there, but almost always at the expense of lack of disease resistance and durability. The plants themselves were largely unattractive, shedding leaves to blackspot unless sprayed regularly and often.
There have been some 20th-century breeders who laid the groundwork for Knockout roses by focusing on disease-resistance. Dr. Robert Basye is a prime example.
The largest nurseries, however, continue to push hybrid teas and grandifloras. The American Rose Society is culpable as well. If one peruses their All-America Rose selections of the past half-century, it is clear that disease resistance was rarely a factor in their selections. How many of those All-America Rose Selections have stood the test of time? How many are still grown today? (To be fair, the original Knock Out Rose was named an All-America Rose Selection in 2000).
Knock Out roses: a nod to environmental responsibility
Maybe you have a friend who abhors any garden not committed 100% to native plants. This friend might even hold up rose gardening as being environmentally irresponsible. With the need for spraying and chemicals, our friend believes roses just have to go.
The answer does not lie in eliminating roses from our gardens. The answer lies in the responsible breeding of plants that have no negative environmental impact. Knock Out roses are an example of doing something right for the right reasons and I can get behind that.
Then we can just argue the aesthetics, which is fine by me.
William Radler: breeder of Knock Out roses
William Radler, who is a landscape architect, by the way, has been breeding roses for decades, since the mid-1970s. He is a native of the upper midwest, so it is understandable that Mr. Radler breeds roses known for cold hardiness.
Mr. Radler has a deep appreciation and history of garden roses. He is also bluntly to the point when describing David Austin roses as “…not good shrub roses” due to their growth habit.
While I agree with Mr. Radler’s sentiment, it is hard to deny the beauty of the David Austin roses. If Mr. Austin could give us just a few disease resistant roses with the beautiful old rose form he develops so well, David Austin would be my rose gardening hero. For now, breeders like Mr. Radler and Dr. Basye will do nicely.
To understand what makes Knock Out roses easy to grow, do not think ‘easy or hard to grow’. Think cultural latitude.
Roses have a reputation for being hard to grow. I do not view plants as hard to grow or easy to grow. A plant that is highly adaptable to a wide range of conditions will be easy to grow. It has a wide cultural latitude. Conversely, a plant that has very specific requirements in order to survive has a narrow latitude and may be considered difficult to grow.
Modern roses bred mid- to late twentieth century have very specific growing requirements (narrow cultural latitude). Knock Out roses are highly adaptable to growing conditions.
Thanks to William Radler’s breeding goals, Knock Out roses survive both hot summers and cold winters. Knock Out roses do not need spraying and are more tolerant of different soil types (wide cultural latitude).
The example set by Knock Out roses shows the potential for a new beginning in rose breeding at a time when environmental responsibility mandates foregoing insecticides and other sprays in the landscape. I hope rose breeders follow the example set by Knock Out roses. We might soon see more new roses that are both beautiful and smart.