Hydrangeas on the Prairies
Which hydrangeas come back and flower in Alberta, Saskatchewan and Manitoba, and how to prune them.
Hydrangeas on the Prairies are a question of which kind you plant. Panicle and smooth hydrangeas form their flower buds on new growth each summer, so a hard winter that kills the stems back does not cost you the flowers. Bigleaf hydrangeas form next year’s buds the summer before, and a Prairie winter usually kills them.
The University of Massachusetts rates panicle hydrangea the hardiest of the species and smooth hydrangea a step behind it. Its sister fact sheet rates bigleaf hydrangea only to a much milder zone, with protection needed below that.
Prairie hydrangeas at a glance: Plant panicle (e.g. Limelight, Quick Fire) or smooth (e.g. Annabelle, Incrediball) hydrangeas. Both bloom on new wood, so they flower even after the stems die back. Bigleaf hydrangeas bloom on old wood and rarely flower after a Prairie winter. Prune panicle and smooth types in late winter or early spring.
Pruning this spring? See How to Prune Hydrangeas in Canada for the cut that suits each type.
Prairie City Zones
Canadian hardiness zones for the main Prairie cities, from this site’s zone data.
| City | Canadian Zone |
|---|---|
| Prince Albert | 2b |
| Saskatoon | 3a |
| Regina | 3a |
| Winnipeg | 3a |
| Brandon | 3a |
| Calgary | 3b |
| Red Deer | 3b |
| Edmonton | 4a |
| Lethbridge | 4b |
| Medicine Hat | 4b |
Panicle Hydrangeas: the Safest Choice
The University of Massachusetts calls panicle hydrangea (Hydrangea paniculata) the most adaptable of the species: more tolerant of dry spells and full sun than the others, and the hardiest. It blooms on new wood. The University of Minnesota Extension, writing for a climate much like the eastern Prairies, names Quick Fire, Limelight and Berry White among its favourite panicle hydrangeas.
Prune back to just above a fat bud in late winter or spring. The University of Minnesota suggests waiting until then so the cone-shaped flower heads give winter interest.
Smooth Hydrangeas: Cut Back, Still Bloom
Smooth hydrangea (Hydrangea arborescens), such as Annabelle and Incrediball, also flowers on new wood. The University of Massachusetts notes it may die back to the ground in a very cold winter and still bloom the next year.
The University of Minnesota’s advice is to let a new plant grow for a season or two, then prune it to the ground in spring, or not at all if you want a larger shrub.
Bigleaf Hydrangeas on the Prairies
Bigleaf hydrangea (Hydrangea macrophylla), the blue or pink mophead, forms its flower buds in late summer for the following year. A Prairie winter usually kills those buds, so the plant leafs out and does not flower. Reblooming cultivars such as the Endless Summer series also flower on new wood, so they can still bloom after the old buds are lost, but the University of Massachusetts notes most of the bloom still comes from old wood. On the Prairies, treat bigleaf as an experiment. The winter protection guide covers what helps.
Water and Siting
The University of Massachusetts says hydrangeas want consistently moist, well-drained soil with plenty of organic matter, about 2.5 cm (one inch) of water a week, more in hot dry spells, and a mulch over the roots kept off the crown. On dry, windy Prairie sites, that watering matters as much as hardiness.
The University of Minnesota recommends a ring of hardware cloth around bigleaf stems in winter to stop rabbits browsing them.
Frequently Asked Questions
Can hydrangeas grow on the Prairies?
Yes. Panicle and smooth hydrangeas bloom on new wood, so they flower even after a hard winter kills stems back. The University of Massachusetts rates panicle hydrangea the hardiest of the species.
Which hydrangea is hardiest for Saskatchewan or Manitoba?
Panicle hydrangea, such as Limelight or Quick Fire. Smooth hydrangea, such as Annabelle, is the next choice; it can die to the ground in a cold winter and still bloom.
Will a bigleaf hydrangea bloom in Calgary or Edmonton?
Rarely. Bigleaf hydrangeas form next year's flower buds in late summer, and a Prairie winter usually kills them. Reblooming types can flower on new wood but give most of their bloom on old wood.
When should I prune hydrangeas on the Prairies?
Panicle and smooth types: late winter or early spring, since they bloom on new wood. The University of Minnesota suggests leaving panicle flower heads on through winter for interest.
Why did my Annabelle die back to the ground?
Smooth hydrangeas often do in cold winters. The University of Massachusetts notes they still bloom the next year because they form flower buds on new wood.
How much water do hydrangeas need?
About 2.5 cm (one inch) a week, applied as a deep soaking, and more in hot, dry weather, according to the University of Massachusetts.
Sources
- University of Massachusetts Amherst Extension — Growing Hydrangeas
- University of Massachusetts Amherst Extension — Why Hydrangea macrophylla Don’t Flower
- University of Minnesota Extension — Pruning hydrangeas for best bloom