Roses rated for Canadian hardiness zone 3b, the zone of Winnipeg, come through a Manitoba winter. That means rugosas, the Explorer series and the Parkland roses bred at Morden. Most hybrid teas, tree roses and English roses do not, at least not without real work every fall. A few shrub roses sit in between, dying back to the snow line and growing again from the base. Knowing which group a rose belongs to before you pay for it saves a lot of dead canes. Care basics are covered in growing roses in Manitoba.
Which roses survive a Manitoba winter
What does Canadian zone 3b mean for a rose?
Natural Resources Canada places Winnipeg in Canadian hardiness zone 3b. That is a Canadian zone, and it does not convert to a USDA zone. The Canadian system is built on seven climate variables, while the USDA system uses one, and NRCan itself says there are no simple conversions. Its own example: Canadian zone 4a overlaps nine USDA zones, from 3a to 7a. If a plant tag or a catalog gives a USDA number, treat it as a different measurement and not as a match.
Zone 3b is also the zone of the reference city, not of the whole province. Northern and upland districts run colder, and a sheltered yard in the city can run milder.
Which types of rose clear zone 3b?
Rugosas sit at the cold end of what roses can take. They are tough, wrinkled-leaved shrubs that shrug off cold that kills most garden roses, and they usually need no winter cover. The Explorer series, bred in Canada for exactly this kind of climate, comes next. Many Explorers carry canes through the winter, and the ones that die back regrow from the base. The Parkland roses, bred at the Morden research station in southern Manitoba, were developed for the prairie and perform similarly.
Hybrid teas, floribundas and grandifloras are rated for milder zones than Winnipeg’s. In zone 3b they need winter work every year, and even then some do not make it. The methods are laid out in Protecting Roses Through a Manitoba Winter.
How do frost dates fit in?
At the Winnipeg Richardson airport station, Environment and Climate Change Canada’s climate normals put the average last spring frost on May 23 and the average first fall frost on September 22. Those are midpoints. In one year out of two, the last frost comes later than May 23, and in one year out of two the first fall frost comes later than September 22. Districts to the north run weeks behind the airport. For roses, the practical meaning is that a bush leafing out in a warm early spring can still be nipped, and new canes that are still soft when freeze-up arrives are the ones most likely to die over winter.
Named roses that hold up here
Which rugosas are the safest bet?
Hansa is a rugosa with double, reddish-purple flowers and a strong clove scent, followed by orange-red hips. It is very hardy and grows on its own roots. It also spreads by suckers, so give it room or plant it where a thicket is welcome. Therese Bugnet is a hybrid rugosa bred in Alberta, with pale pink, fragrant flowers on reddish canes. It stays tidier than Hansa and handles prairie cold without cover. Both have the leathery, wrinkled foliage that resists much of what the climate here brings, a subject covered in Rose Diseases in Manitoba: What the Climate Here Actually Brings.
Which Explorer and Parkland roses perform?
William Baffin is an Explorer climber with bright pink, semi-double flowers on tall canes. It is one of the few climbers that regularly carries its canes through a prairie winter, though snow cover helps. Winnipeg Parks, a Parkland rose, is a compact shrub with cherry-red to pink flowers. Morden Blush, also a Parkland rose, is a low, pale pink shrub that suits a front bed. All three were selected for cold hardiness, so a hard winter usually costs them some tip growth and not the plant.
Do Knock Out and New Dawn hold up?
Knock Out is sold in nearly every garden center, and it does grow here, but it is a die-back shrub. In a hard winter the canes often die to the snow line or lower, and the plant regrows from the base. It flowers on new wood, so the loss costs height and not blooms. In spring, prune out all the dead canes once the live buds show.
New Dawn, a pale pink climber, is a different story. Its canes freeze in zone 3b unless they are protected, and a climber that loses its old canes loses much of its bloom. It can be grown here only if you are willing to lay the canes down and cover them each fall. Treat it as a project and not as a plant that looks after itself.
Sold here, but not for this zone
Garden centers stock roses nationally. The same truck that serves a milder region delivers to Manitoba, and the shelf does not sort by hardiness. Plant tags may carry a USDA zone or a Canadian one, and the numbers do not line up, so a “zone 4” tag tells you little unless you know which system printed it.
Hybrid teas are a large group in this category. Familiar names such as Peace and Mr. Lincoln show up in catalogs across the continent, but they are rated for milder winters. Without cover they commonly die to the ground, and the graft often dies with them. Tree roses, also called standards, are worse off. A tree rose is a rose grafted on top of a straight trunk, so the trunk and the graft are both exposed to wind and cold. They are usually buried or wrapped, and many gardeners treat them as annuals.
English roses and many floribundas fall in between. Some survive with mounded soil, and others die back so hard that they never reach full size. Potted miniature roses sold indoors around Valentine’s Day are greenhouse-forced plants. They are generally not suited to outdoor planting here. And large climbers bred for mild regions, including some sold in spring already leafed out, will flower poorly when their canes freeze.
Buying one of these is not a mistake if you want the flower and are ready for the upkeep. Plant one anyway and budget for winter cover every fall, using the methods in Protecting Roses Through a Manitoba Winter. If you want a rose that needs no such effort, pick from the rugosa, Explorer and Parkland groups above.
What to check on the label before buying
Start with the grade. Grade 1 is the top grade for field-grown, bare-root roses, and it means heavier, better-developed canes than the lower grades. Bagged roses in big-box stores may be a lower grade, and a weaker bush has fewer reserves to recover from a hard winter.
Then check whether the rose is grafted or grown on its own roots. A grafted rose has a swollen knob near the base, called the bud union, where the variety was joined to a different rootstock. An own-root rose is the variety all the way down. The colder the winter, the more this matters. When a grafted rose freezes to the ground and the graft dies, the shoots that come up in spring grow from the rootstock and not from the variety you bought. They often look nothing like it. An own-root rose that dies to the ground regrows as the same rose. For anyone in zone 3b, choose own-root plants whenever the label offers the choice.
Read the rest of the tag with the same care:
- Which hardiness system is printed, Canadian or USDA
- The series name, such as Explorer or Parkland
- Whether “own root” is stated
- Whether the canes are green and plump, not shriveled or black
Checking this against your own county
Manitoba is divided into rural municipalities rather than counties, and conditions shift from one to the next. Natural Resources Canada’s plant hardiness site lets you look up your own location, so check your zone there before you buy anything marginal. For local conditions, such as how cold the winters run in your district and how late frost tends to arrive, ask Manitoba Agriculture, the provincial agriculture department, or a local garden club or nursery that sells roses grown on the prairie.
Common questions
Can I grow hybrid teas in Manitoba?
Yes, but they take work every fall and some will not come back. Hybrid teas are rated for milder zones than Winnipeg’s Canadian zone 3b. If you want to try one, plan on mounding soil or another form of cover each year, and treat any survivor as a bonus.
Do Explorer roses need winter protection?
Most do not. The Explorer series was bred in Canada to survive cold winters. Some tip die-back is normal, and climbers such as William Baffin do better when snow covers the lower canes. Prune out the dead wood in spring and the plant regrows.
Is Canadian zone 3b the same as USDA zone 3?
No. The two systems measure different things. The Canadian system uses seven climate variables and the USDA system uses one, and NRCan says there are no simple conversions between them. Always check which system a tag or catalog is using.
Why does own-root matter so much in the cold?
Because a hard winter can kill a graft while leaving the roots alive. On a grafted rose, the shoots that follow come from the rootstock, which is a different rose. An own-root rose that freezes to the ground regrows as the variety you chose.