What’s so hot about ‘Knock Out’ roses, anyway?

Q. What’s the big deal about the Knock Out roses? They are supposed to be ever-blooming, resistant to black spot, but the blooms just don’t seem to be that great. My rose called The Fairy is all of those things, but while the flower is smaller, it is better looking than any of the Knock Outs that I have seen in the stores.

A. The Fairy entered the rose marketplace in 1932 and over the past 75 years, has not gained much of a following, even with its resistance to disease and the long bloom season. When rose gardening resumed in the post-war decades, The Fairy simply didn’t compete with such beauties as Queen Elizabeth, Mister Lincoln and Peace, three esteemed roses of the 20th century. The Fairy, bearing clusters of charming pink flowers on a shrub 2 to 3 feet tall, remained out there, but you had to search for it and even more so today. It is in catalogs of specialists in shrub and heirloom roses and sometimes in stores. Perhaps it needed a press agent.

Now, since 2000, we have the Knock Outs, counting the original cherry red and the newer pink ones that followed. They, and others of the shrub roses such as Bonica and Carefree Delight, have regenerated interest beyond measure in roses. I am grateful for them because millions have been planted in America, and often by people who wouldn’t consider hybrid tea roses — even one as historic as Peace — because of the meticulous attention to combating diseases they require. And they have press agents.

The individual flowers of the Knock Outs are uncomplicated blooms that resemble larger wild roses. But it is the overall effect of a large roundish shrub in bloom that is stunning. I don’t think The Fairy can compete as a landscape plant on this score, even if enough were on the market to raise interest among gardeners.

Rose gardening appeals to different interests. For serious rosarians willing to make the steady effort to care for them, nothing beats hybrid tea and grandiflora bush roses for exquisite blooms. Some people like the old-fashioned heirlooms that have been around for centuries but tend to have a shorter bloom season than modern roses. Others, and I think this is what has made Knock Outs so incredibly popular, just want low-maintenance roses for their landscape that bloom for a very long time with beautiful color and excellent resistance to disease.