Behind every good plant is a story. Plants that make their way into our gardens don’t just happen. There are years of breeding and testing before they earn the right to come home with us. What I find fascinating is the personalities behind the plants, the story of the individual who had the vision to create a great plant, or the blind luck to stumble upon a gem!
William Radler is the force behind the “Knock Out” series of roses. These are quickly becoming a top-selling rose, bred with cold-hardiness and disease resistance in mind and performing admirably in many different climates across North America.
Radler’s roses certainly didn’t happen by chance. Roses were his passion from an early age. I read Superman comics when I was a young boy; he passed the time looking through rose catalogs. He bought his first rose for 49 cents at the age of 9 and was hooked when the first bloom appeared.
By age 17 he was a charter member of Milwaukee’s North Shore Rose Society and through propagation and bud grafting he’d amassed a collection of over 200 roses in his parents’ garden.
It didn’t take Radler long to realize that caring for all these roses was a lot of work. Spraying for black spot, a disease which causes leaves to produce black spots before they turn yellow and fall off the plant had to be done weekly. Radler noticed that other rose lovers were cutting back on their gardens because of the time involved in maintaining healthy roses.
So he set out to develop roses that didn’t require as much maintenance. He wanted to make them hardy enough so that gardeners in colder climates didn’t have to apply winter protection, or replace the plants when the protection failed. Disease resistance would eliminate the need for costly and time-consuming sprays.
To create a new rose you need to cross-pollinate two plants. You take pollen from the male part of one rose and put it on the female part of another rose. It sounds simple, but it’s a whole lot more complicated than that.
You don’t find all the traits you’re looking for after one cross. That would be blind luck. You have to pollinate many roses, many hundreds or even thousands of roses. Some plants are female sterile; they don’t produce any seed and although the plant may have all of the qualities you’re looking for if there’s no seed how can you replicate those qualities?
And, one more thing, only one in three cross-pollination attempts are successful. Radler has crossed thousands of roses during his career as a breeder, always with that vision in mind, a hardy plant with no black spot that anyone can grow.
To test for disease resistance he collects diseased leaves and dries them. Then he puts them in a grinder to create a powder and sprinkles the powder over the rose garden after the leaves are watered overhead. After a few weeks of inoculation the diseases begins to emerge and before too long most of the plants are full of black spot.
But not all of them. The plants which resist infection are selected for further breeding and the process continues. The roses that produced “Knock Out” weren’t ideal candidates. The father didn’t produce any rose hips, or seeds, but was a good source of pollen and the mother produced only a few hips. In fact, the mother plant germinated from the only seed that Radler was able to get from one hip. Most rose hips contain 30 to 50 seeds.
The first “Knock Out” rose was created in 1988. It was sent to the Conard-Pyle company for testing in 1992 and in 2000 “Knock Out” received an All American Rose Selection award.
Radler is still hard at work trying to create more roses with different colours, fragrances and sizes. His goal is to have so many introductions that they’ll have a catalog of their own.
