Hello, I live in the city of Toronto, zone 6a, and have a small rock garden on the slope of my front lawn edging the sidewalk and facing south. The soil is loamy. At the top of the rock garden, are three polyanthus roses and a rugosa. This year, even though I prune spring and fall, the growth has overshadowed the flowers on the slope. When do you recommend pruning again? The roses are massively blooming now!
Thank you for contacting the Toronto Master Gardeners. It must be satisfying to have such healthy rose bushes in your garden. The primary time for pruning roses is in early spring when leaf buds on the canes swell and are ready to break. Polyanthus roses can be pruned in the summer to stimulate more blooms and to keep its shape. Using disinfected secateurs, cut off faded blooms a quarter of an inch above the 1st five leaflets on the stem of the bush. Make the cut facing outward so the bush grows outward. To stimulate more flower-producing wood, healthy green wood can also be pruned a third time in mid-summer after each flush of flowers is finished. To maintain the shape of the plant also prune overly long canes. The article How to prune roses/Gardenmaking by Judith Adam provides helpful guidance on this topic. Another excellent resource is Growing and caring for roses by Ursula Schuch.
In terms of the rose bushes overshadowing the other flowers on the slope, is it possible that the rose bushes and the other flowers are planted too closely together? Perhaps when the weather is not too hot some of the flowers can be moved to create more space between them and the rose bushes.
Good luck with your garden.
June 9 2021