Earlier this month my master gardener group had a tour of the Centennial Rose Garden at the Royal Botanical Gardens in Hamilton. The reason behind our visit was to learn about the changes the gardens have made or had to make since the Ontario pesticide ban in 2009. Through consultation with other large gardens they have returned to 'heritage' care techniques, or in other words, organic practices. Not surprisingly, this is not as easy a feat to accomplish with gardens of its size and unfortunately a lack of funds to support their endeavors in order to present the gardens at the level of quality for a botanic garden.
The main problem they deal with in the rose garden is black spot. Anyone who grows roses knows this problem well. How do you create beautiful beds of let's say hybrid teas when all their bottom leaves are turning yellow and falling off? Not a pretty sight. Keeping the beds clean looking is presently more of a priority than the actual prevention of the problem especially during rose season.
|Climber 'Roberta Bondar'|
The problem of black spot is the result of the way they prepared the beds for the winter. Each rose bed was covered with a plastic sheet of polyfoam and then trenched in. Even the climbing roses received the same practice being removed from their supports, laid on the ground and covered in polyfoam. Black spot, weeds and mice thrived under the plastic and after years of following this practice the soil is completely infected with the fungus. To add to this, most rose beds are grown just as that, rose beds. This creates a monoculture in which pests and diseases thrive.
In the last few years there have been changes including planting roses that are hardier for our zone, growing more shrub roses like rugosas which are relatively trouble free, and growing more disease resistant varieties such as the 'Knockout ' roses. They are also playing with some new mixed plantings such as roses, clematis and grasses.
|Captain Samuel Holland|
|Bed of species roses|
|rosa foetida bicolour 'Austrian Copper'|
|rosa foetida 'Persian Yellow Rose'|
|Knockout roses with clematis and panicum 'Heavy Metal'|
|Knockout 'Carefree Celebration'|
|gorgeous Knockout - sorry never got the name|