Are Hydrangeas Perennials? A Complete Guide for Toronto Gardeners
Yes, hydrangeas are perennials in Toronto. Learn about the different types, bloom times, pruning schedules, care tips, and important considerations for pet owners.
Hydrangeas are among the most popular flowering shrubs in North American gardens—and for good reason. They’re showy, low-maintenance, and come in a wide variety of colours and forms. But one of the most common questions homeowners ask is: Are hydrangeas perennials? In this guide, we’ll explore the answer, break down care routines like pruning and cutting back, outline bloom times, and discuss safety around pets.
Did you know? According to the National Gardening Association, hydrangeas consistently rank among the top 10 most popular perennials in Canada and the U.S., with over 11 million units sold annually across North America (National Gardening Association, 2022). In Toronto, their resilience and beauty make them a favourite choice for front yards and shaded gardens.
Yes—Hydrangeas Are Perennials in Toronto
Hydrangeas are classified as deciduous perennials, which means they die back in the winter and return each spring. In Toronto’s Plant Hardiness Zone 6, most hydrangea varieties perform very well. Hydrangea offer interest all year with beautiful blooms that turn to pinks and blues and reds in late summer, foliage can be burgundy in fall and spent flowers can be left on the plant for winter interest. With proper care, they can live for decades, producing reliable blooms year after year.
There are several types of hydrangeas that are popular in Toronto:
Hydrangea macrophylla (Bigleaf Hydrangea): Famous for pink, blue, or purple mophead or lacecap blooms.
Hydrangea paniculata (Panicle Hydrangea): Cone-shaped white flowers that mature to pink or rose.
Hydrangea arborescens (Smooth Hydrangea): Known for massive white flower heads—‘Annabelle’ is a popular cultivar.
Hydrangea quercifolia (Oakleaf Hydrangea): Unique oak-like foliage and long-lasting flowers.
Hydrangea anomala petiolaris (Climbing Hydrangea): Vigorous climber for shade gardens.
HYDRANGEA MACROPHYLLA. From left to right: Bloomstruck, Gin ‘n Tonic, Let’s Dance Can Do!, Summer Crush
HYDRANGEA PANICULATA. From left to right: Little Lime, Little Quick Fire, Pee Wee, Strawberry Sundae
HYDRANGEA ARBORESENCE. From left to right: Anabelle, Ruby, Limetta, Mini Mauvette
HYDRANGEA QUERCIFOLIA. From left to right: Queen of Hearts, Alice, Munchkin, Oak Leaf
HYDRANGEA ANOMALA PETIORALIS
When Do Hydrangeas Bloom?
Bloom time depends on the type of hydrangea, but generally speaking, hydrangeas bloom between late spring and early fall, offering months of colourful impact.
Bigleaf hydrangeas: June to August (depending on winter dieback)
Panicle hydrangeas: July to September
Smooth hydrangeas: June to early September
Oakleaf hydrangeas: Late June to August
Weather can affect bloom timing. Late frosts in Toronto may delay Bigleaf hydrangeas, which bloom on old wood, meaning they rely on buds formed the previous year.
When to Cut Back Hydrangeas
Cutting back hydrangeas is different from pruning (we’ll cover that next). Cutting back typically means trimming the stems significantly to manage size, rejuvenate the plant, or clean up dead material in early spring or late fall.
Smooth hydrangeas (e.g., Annabelle): Cut back hard in early spring to about 12-18 inches. They bloom on new wood.
Panicle hydrangeas (e.g., Limelight): Also bloom on new wood. Cut back by one-third in late winter or early spring.
Bigleaf and Oakleaf hydrangeas: These bloom on old wood. Only remove dead or weak stems after blooming—do not cut back drastically or you’ll lose next season’s flowers.
Rule of thumb: If it blooms on new wood, you can cut back in early spring. If it blooms on old wood, wait until after flowering and avoid heavy cuts.
When to Prune Hydrangeas
Pruning is different from cutting back. It involves removing dead, diseased, or weak stems, and shaping the plant for aesthetics and airflow.
For Bigleaf and Oakleaf hydrangeas: Prune immediately after blooming in late summer. Only remove up to one-third of the oldest stems.
For Smooth and Panicle hydrangeas: Prune in late winter or early spring before new growth appears.
Toronto Tip: Prune in early March to early April, depending on snow melt and frost forecasts. Avoid pruning too early—bud damage can happen in freezing conditions.
Are Hydrangeas Toxic to Pets?
Unfortunately, yes—hydrangeas are mildly toxic to pets. According to the ASPCA (American Society for the Prevention of Cruelty to Animals), hydrangea leaves, buds, and flowers contain cyanogenic glycosides.
Cats and dogs: Can experience vomiting, diarrhea, and lethargy if large amounts are ingested.
Horses and livestock: Also susceptible to toxicity if consumed.
What to do: While cases of serious poisoning are rare, it’s best to plant hydrangeas out of reach of curious pets or consider safer alternatives like snapdragons or petunias if you're worried.
How to Care for Hydrangeas Year-Round
Hydrangeas are relatively low-maintenance perennials, but a few seasonal care tips ensure optimal performance:
Spring
Prune or cut back based on type.
Apply a slow-release fertilizer (10-10-10).
Mulch to retain moisture and suppress weeds.
Summer
Water deeply once or twice a week—especially in heatwaves.
Deadhead spent blooms to encourage more flowers (optional).
Check for pests like aphids and spider mites.
Fall
Let spent flowers dry—adds winter interest and protects buds.
Stop fertilizing by early September to help harden stems.
Winter
For Bigleaf hydrangeas, add a burlap wrap or mulch mound around the base to protect buds.
Panicle and Smooth hydrangeas need minimal winter protection in Toronto.
Common Hydrangea Mistakes (and How to Avoid Them)
Pruning at the wrong time: Cutting back old wood bloomers in spring means no flowers that year.
Too much shade: While hydrangeas like dappled light, deep shade reduces blooms.
Not enough water: Hydrangeas have shallow roots—mulch and water deeply.
Wrong fertilizer: Avoid high-nitrogen fertilizers—they encourage leaves, not flowers.
Why Toronto Gardeners Love Hydrangeas
Hydrangeas are a go-to perennial in the GTA because:
They’re cold-hardy and return every year.
They provide long-lasting seasonal colour.
Many varieties thrive in part-shade—a common condition in urban yards.
They pair beautifully with other perennials like hostas, astilbes, and ferns.
If you’re considering planting hydrangeas in your garden, rest assured: they are a worthy investment that pays off in vibrant colour, structure, and timeless appeal.
Ready to Plant or Revive Your Hydrangeas?
At Master in the Field, I help Toronto homeowners design stunning perennial beds—including hydrangeas—that thrive in our urban climate. Whether you're planting your first hydrangea or need help reviving an overgrown one, I offer customized garden consultations to guide you.
Ready to transform your outdoor spaces? Contact me today for personalized landscaping ideas tailored to your needs. PLUS…visit my Inspiration Page for more front yard landscaping ideas perfect for your Toronto landscaping projects.
References
ASPCA. (2023). Hydrangea Toxicity. Retrieved from https://www.aspca.org/toxic-plants/hydrangea
National Gardening Association. (2022). Garden Trends and Top-Selling Perennials. Retrieved from https://garden.org/learn/articles/top-selling-perennials
Landscape Ontario. (2021). Hydrangea Pruning Tips. Retrieved from https://landscapeontario.com/hydrangea-care
Toronto Master Gardeners. (2021). Growing Hydrangeas in Toronto. Retrieved from https://www.torontomastergardeners.ca/hydrangea-guide
