How to winterize hydrangeas in Canada?

Snow cover not only provides insulation, but also a water source . If you live in an area that doesn't have snow — or doesn't get snow — make sure you've got enough rain or water to get them through. Also, be sure the base of the hydrangea is covered with wood chips, oak leaves, pine straw or other mulch.

Can hydrangeas survive in Canada?

Hydrangeas are one of the best plants to grow in Ontario for so many reasons. Hydrangeas are easy to grow and care for and they typically do well in shady spots although some of the newer varieties are full sun plants.

How cold is too cold for hydrangeas?

The hardiness zones for H. macrophylla are 6 to 9. Effectively, a hydrangea should be able to sustain a temperature of minus-10 degrees. But in the real world, temperatures as low as 12 degrees — and late fall or early spring freezes — may reduce the flowering capability of this hydrangea.

Do I need to cover my hydrangeas for winter?

Whether or not hydrangeas need protection depends on how cold the winter temperatures drop. If the air temperature doesn't go below 0 degrees (zone 7) there is no need for winter protection . In colder climates, wrap or completely cover marginally hardy hydrangeas.

Growing hardy hydrangeas in northern Canadian gardens (2024)

Choosing the Best Hardy Hydrangea For Your Garden (And How To Make It Thrive)

2/13/2015

35 Comments

In recent years, hardy hydrangeas have become one of the most popular flowering shrubs and it's easy to understand why.Hydrangeas are showy, versatile, adaptable, and easy to maintain.

Hydrangea'sWinning Features

Hydrangeas are:

Cold hardy and dependable
Easy to grow
Rarely bothered by diseases or pests
Suited to shade (minimum 3 hours/day) or sun
One of the few shrubs that bloom late summer through fall
Long-blooming
Require little pruning

You really couldn't ask much more of a shrub.

Plant breeders have invested millions into developing new hardy hydrangea varieties over the last decade. Every season, it seems that a few more varieties are brought to market, giving the home gardener ever more options. But which one is best for you?

'Little Lamb' Hydrangea

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Hydrangea Types & Characteristics

The first thing you should know is that not all hydrangeas are hardy. In particular, I'm referring to the mophead hydrangeas (hydrangea macrophylla). Mophead hydrangeas are the those stunning blue and pink ones you see all over the Lower Mainland.

The hydrangeas thatdooverwinter well here are thepanicletype (hydrangea paniculata) andsmoothtype (hydrangea arborescens).

Sorry, these are not hardy hydrangeas!

'Pinky Winky' panicle hydrangea

'Incrediball' smooth hydrangea

Flowers

Panicle hydrangeas are said to have cone-shaped flowers, but I only partially agree with that description. I would say that the cone shape may be very distinct or very vague, depending on the variety. Flower size also ranges greatly.

Smooth hydrangeas have broader, dome-shaped flowers. Flower size is more consistent (about 6-12" in diameter) between varieties.

With regard to flower colour, hardy hydrangeas are endless shades of white, pink, and lime. As the flowers age, they often take on changing tones and/or different colors.

Hardy hydrangea flower color is unaffected by the soil's pH level.

Foliage

Panicle hydrangeas have reddish, woody, sturdy stems, whereas smooth hydrangeas have green, flexible, relatively soft stems. This is because panicle hydrangeas regrow on previous season's growth and smooth hydrangeas grow anew from the ground each year.

Panicle hydrangea leaves also tend to be darker green and more leathery; smooth hydrangea leaves are lighter green and softer.

Pruning

A major difference between panicle and smooth hydrangeas is their pruning requirements.

Panicle hydrangeas only need only a light annual trimming of the branch tips. (The exception to this is if you have an old panicle hydrangea that is not blooming well any more. In that case, the hydrangea will need "motivation" to bloom again. Just cut back a few of the oldest stems as low to the ground as possible in early spring.)

Smooth hydrangeas need a hard annual pruning in early spring, Cut back all stems to about
3-6" from ground level.For this reason, smooth hydrangeas are the better choice if your desired planting site is subject to heavy winter snow loads.

Plant Size

A mature hardy hydrangeacan be as little as 3' x 3' or as large as 10' x 10', depending on the variety.

Usage

As demonstrated in the photo gallery below, hydrangeas can be planted as:

a feature shrub or as a combination with other perennials/shrubs
as a foundation planting (meaning against the foundation of a house)
as a mass planting
as a hedge
as a small tree (see note below)

Note-Tree hydrangeas are simply hydrangea shrubs trained into a tree form. This process takes several years of selective pruning. If you have the patience, any hydrangea can be trained into a tree (otherwise, ready-made tree hydrangeas are available.)

Planting and Growing Information

Hydrangeas are easy to grow but they do need moist soil. Hydrangeas resent being dry and they will show it.If you prepare your soil properly, add mulch around the shrub base, and water deeply but infrequently, your hydrangea should thrive.

Different hydrangea varieties tolerate varying degrees of shade.Generally speaking, hydrangeas are adaptable to sites that receive a minimum of 3 hours of sun daily.

Since hydrangeas flower prolifically, fertilizing is a good idea. For the first year, only use bone meal and transplant fertilizer. After that,apply a slow-release fertilizer yearly to maximize flower production.

Recommended Varieties

I've yet tomeet a hydrangea that I didn't like, but here is a broad sampling of the available varieties:

Hydrangea Paniculata 'Bombshell'

Once you see this hydrangea in full bloom, you'll agree that it's aptly named. Whenflowering, Bombshell is smothered in so many blossoms that you can barely see its leaves. In fact, it produces more flowers than any other panicle hydrangea.

The flowers start out white but slowly age to soft pink. Bombshell starts blooming earlier than most panicle hydrangeas and also has a longer flowering period.

Bombshell is a dense and tidy little hydrangea, maturing to about 3' high and wide.

Photo courtesy of Van Belle Nursery

Hydrangea Arborescens 'Invincibelle Spirit'

Invincibelle Spirit is the first (and only) pink flowered smooth hydrangea, which is why it made the list. The large, dome-shaped blossoms are produced from mid to late summer.

Invincibelle Spirit is a medium sized hydrangea, eventually reaching 3-4' high and wide.

Hydrangea Arborescens 'Incrediball'

Incrediball is the new and improved version of 'Annabelle'. (Annabelle was discovered in Anna, Illinois in 1910.) Though lovely, Annabelle's blossoms tend to flop, giving the plant a messy appearance. Should a heavy rainstorm strike an Annabelle, it looks more like a tornado touched down on it.

On the contrary, Incrediball has remarkably stiff, strong stems to keep the flowers upright. And the kicker is, Incrediball's flowers are even bigger, reaching up to 12" in diameter! The flowers open lime green, turn white when fully open, and then revert back to lime green.

Incrediball grows 4-5' high and wide.

Hydrangea Paniculata 'Little Lime'

Little Lime is my latest hydrangea infatuation. We had a beautiful display of them at our front entrance last season and I couldn't keep my eyes off of them. On several occasions, I got close to admire their mesmerizing, artfully colored blossoms.

Little Lime has dense flower clusters, ranging from white to lime to pink, and everything in between. It is highly productive in terms of flowering.

Little Lime is a dwarf hydrangea, topping out at about 3' high and wide.

Hydrangea Paniculata 'Quick Fire'

Quick Fire is a valuable variety because it starts blooming one month earlier than any of the other hardy hydrangeas.

Quick Fire has a loose and airy flower shape. The blossoms emerge white, turn to pink, and eventually deepen to a cherry red.

Quick Fire is one of the largest hydrangeas, maturing to 6-8' high and wide.

Hydrangea Paniculata 'Fire Light'

2014 was only the first year we grew Fire Light. However, its unique flower color and shape makes it worthy of mentioning.

Like most pink hydrangeas, Fire Light flowers start out white and darken to a rich pink color. The flower panicles have a particularly distinct, dramatic shape.

Fire Light grows anywhere from 5-6' high and wide.

In Summary...

Hardy hydrangeas are exceptional flowering shrubs for our area.If you see a hardy hydrangea variety that I don't mention here, give it a try anyway. Chances are you will love it.

Check out the Proven Winners website to preview many more hydrangeas, including ones that will be released in 2016. I can't wait to try them all!

35 Comments

Sheila Barnes

6/3/2015 11:12:11 pm

Hi can. You explain how to turn a hydrangea cutting into a tree.
I have a rooted cutting from last year, do I just remove side branches as they grow, or wait until it has reached its desired trunk height
Thank you

Lacey Hunniford

6/4/2015 01:57:37 pm

Hi Sheila,

To reference Lois Hole's Favorites Tree and Shrub book, here are the basic points:

- Start pruning shrub when it is 2-3 years established in your garden.
- Create your "tree trunk" by selecting one strong vertical stem.
- Prune off the lower 1/3- 1/2 of horizontally growing branches, starting at the base of shrub.
- In subsequent seasons, continue pruning off any horizontally growing stems (and those that sprout at the shrub base) until you've created the desired tree trunk height..

Julie Culshaw

6/20/2017 09:32:10 am

I have a question about climbing hydrangeas. We live in Nova Scotia and these grow so well here. I would love to try one in our new location which is central Ontario, Barry's Bay, which is zone 4. Will a climbing hydrangea survive in this colder zone? what if I provide some winter protection?

Lacey

6/20/2017 07:10:22 pm

Hi Julie. I would expect it to survive in Barry's Bay, as we are Zone 3/4 and they winter here just fine, without extra protection. If it's grown in a drier climate, it probably will require more frequent watering.

Julie Culshaw

7/4/2018 06:16:59 am

Well they didn't survive, one expired during the winter and the other made it, but wilted away in June. We had a particularly hard winter. I have another one in a different location and will try again. I think I will protect this one for the winter.

Janice Hilton

10/22/2017 10:54:16 am

What a wonderful overview about Hydrangeas. Thank you so much. I have three potted Hydrangea plants (the type from the grocery stores) that I kept in our heated garage each winter. Now, they lost leaves...grew new ones and flowered...I don't know if this is the correct way to do this. I took them out in the late spring; onto the deck and one grew beautifully. Huge flowers. The other two, slowly...slowly grew. I'm in Thunder Bay, Ontario and I have read I could simply keep them in their pots and put them in an unheated enclosed area like an unheated potting shed. Is this true? Thanks in advance for any help. I'd love to keep going with these three beauties. :-)

Lacey

10/22/2017 08:57:23 pm

Hi Janice, that's great :)

The mophead (macrophylla) hydrangeas could be overwintered in an unheated shed - IF your lowest winter temperatures don't drop below about -15 Celsius. Perhaps they could handle as cold as -20 Celsius. Otherwise, I would recommend doing what you're already doing...especially since it worked well for you.

Tina Jacques

6/14/2018 09:52:08 pm

I got the latest Canadian Living magazine, and immediately noticed your ad with the incredible Fire Light Hydrangea. I checked to see if you had a site. The Hydrangeas are so beautiful, and here I thought my pitiful blue ones were the epitome. I would love to know when you would send out your plants.
Also do you propagate other plants? I have been looking for some ladies slippers. I know one is not supposed to harvest them, but surely to grow them for your garden would be okay? That would be increasing their plant base, rather than depleting it. I read an article that said they used to be widespread across Canada, but have been harvested until they are only found in Manitoba and Ontario.

Leslie

7/2/2018 10:26:07 pm

Assuming you live in Canada
Fire light hydrangea:
https://www.homedepot.ca/en/home/p.pw-hydrangea-fire-light-5g.1001048091.html

Tina
It is illegal to remove ladyslippers from the wild and it is just plain wrong. Please don’t do that. Most of the ones illegally dug up die within a few years in the garden hence part of the reason why they are disappearing.
There are many nursaries that sell them. In BC there is Fraser Thimble Farms:
http://www.thimblefarms.com/cypripedium.html
and in Alberta there is :
http://www.gardenslippers.com/
Hope this helps. Good luck

Lacey

7/3/2018 07:56:38 pm

All good points Leslie....thank you for commenting.

Growing hardy hydrangeas in northern Canadian gardens (2024)

Choosing the Best Hardy Hydrangea For Your Garden (And How To Make It Thrive)

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