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Caring for Roses

July 16, 2020

By Christie Brodie, Interpretation Projects Coordinator, Royal Botanical Gardens.

For many gardeners, it’s tricky to have thriving roses. Our northern climates and pesticide bans make rose growing even more of a challenge here in Ontario. But, armed with the right plant choices, information and perseverance, roses can fill your garden with scent and beauty all summer and into the fall.

In recent history, rose cultivation relied heavily on the use of chemicals, such as fungicides and pesticides. With the Ontario Cosmetic Pesticide Ban Act now in place, rose culture needs to shift. There are many beautiful, hardy cultivars that thrive in our Canadian climate. These varieties are cold and drought tolerant, disease resistant, and don’t need chemicals for life support.

While many 21st century roses are chosen for their ability to avoid disease, a vigilant eye is still required to make sure they are healthy and free from black spot, powdery mildew, and rust.

Common Rose Diseases

Powdery Mildew on a rose bush
Powdery Mildew (Photo: Scot Nelson)
Black Spot on rose leaves
Black Spot (photo: Scot Nelson)
Rose Rust on leaves
Rose Rust (Photo: Malcolm Manners)

The best way to keep your roses clean is by choosing blackspot and other disease resistant cultivars. In our own Rose Garden in Hendrie Park, we have chosen cultivars that have proven to be disease-free. However, for older roses with poor genetics (such as hybrid teas and floribundas) pruning off diseased leaves or canes may be necessary. Be sure to tidy all debris from around the base and dispose of it carefully to avoid spread.

Red Canadian Shield Rose Vineland 49th Parallel Collection
Varieties like ‘Canadian Shield’ by Vineland Research and Innovation Centre (Vineland, ON) were bred to withstand our cold winters, hot summers, and be disease resistant.

Common Rose Pests

Also, be mindful that sick roses are more susceptible to insect pests. Keep a keen eye out for these sneaky critters. Common pests include aphids, Japanese Beetles, sawfly larvae, and butterfly or moth caterpillars. Hand-picking, while tedious, is the best chemical-free control for many insect pests. One of the best ways to avoid pests, is to plant companion plants amongst your roses which attract beneficial insects such as ladybugs, lace wings, and parasitic wasps (all which attack pest insect populations).

Japanese Beetle on pink rose
Japanese Beetle
Sawfly Larvae
Sawfly Larvae

Planting Your Roses

Once you’ve picked out the rose cultivar that best suits your preferences, it’s time to get digging. It’s best to plant roses in either spring or late autumn. Here are some tips to help ensure you are starting your new rose off right.

  • Roses thrive in full sun. Choose a well-drained site that gets at least six hours of direct sun daily.
  • Once you have chosen your site, dig a hole deep enough so the bud union (a scar where the stem joins the rootstock) is 5 cm below ground level.
  • Add your plant to the middle of the hole, then fill ¾ full with soil (which can be amended with up to 50% compost) and pack it firm around the rootstock.
  • Water well to remove any air pockets, then finish filling the hole.
  • Soil can be mound-up over the stems for the first 10 days, or until spring if you chose to plant in the autumn to protect the plant.
Diagram of Planting Best Practices

Now that your rose is in the ground, it’s time to take care of it. Roses are needy, but, with a little effort you will have gorgeous roses. Be sure to:

  • Prune dead, damaged, or diseased canes in spring just before bud break, but after the last frost. This timing lines up with when forsythia is in flower, a natural reminder! Make your cuts 6 mm above an outside bud so new growth goes outward.
  • Deadhead spent flowers by pruning back to the first outward, true leaf (with 5 leaflets). Do not deadhead if you want rosehips (which are high in vitamin C and can be made into a variety of tasty treats).
  • Roses need about 2.5 cm of water per week and may need watering if the rain cannot provide it. Always water early in the morning and try to avoid wetting the leaves by watering around the base of the plant.
  • Apply organic fertilizers, such as manure and compost, after spring pruning. Adding mulch will help feed your roses thanks to its slow decomposition.

With a little tender love and care, you’ll have beautiful blooms to enjoy for decades.

Want to know more?

For more information on our Rose Collection, visit:

For more information on rose care, or to ask the experts, be sure to visit the Halton Master Gardeners website. Find them at: 

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