What is a perennial?

A perennial will restart it's growing cycle every year thanks to its resistance to the cold.
A bi-annual is a plant that will flower during its second year of production. The third year it will flower and resow itself.
Certain bulbs such as lilys are considered as perennials.

Hardiness zones

A plant's hardiness is the capacity to resist to average minimal temperature. These zones will be different depending on geographical location.
- Montreal region : zone 1 to 5B
- Quebec region : zone 1 to 4B
- Sherbrooke region : zone 1 to 4B
- Ottawa region : zone 1 to 5A
- Toronto : zone 1 to 5

- Although very important when planning a garden or flower bed, these zones are only to be used as reference. Winters are different every year, certain factor such as snow coverage can play with the plant's hardiness.

Zone establishment in conjuction with winter conditions

Zones and temperature in Celsius:

-Zone 1 : minest –45
-Zone 2A : -46 à –43
-Zone 2B : -43 à –40
-Zone 3A : -40 à –37
-Zone 3B : -37 à –34
-Zone 4A : -34 à –32
-Zone 4B : -32 à –29
-Zone 5A : -29 à –26
-Zone 5B : -26 à –23
-Zone 6A : -23 à –21
-Zone 6B : –21 à –18

Sun exposure

It is very important to know how many hours of sun the flower bed will be exposed
Full sun : more than 8 hours of sun daily
Partial shade : minimum of 4 hours of sun daily
Full shade : less than 2 hours of sun daily


Perennials are sold in containers, they can be transplanted anytime of the season.


Division can be performed in early spring or in fall, not to interfere whit the flowering period. If flowering is not an issue, division can be performed anytime. Avoid division during a drought.


Trimming should be executed after flowering. Removing the wilted flowers and part of the foliage will give your perennial greater vigour and a better appearance.

Preparing perennial for winter

1- Simply let nature follow its course. Leaving the foliage intact will favour snow accumulation and therefor a better winter protection. In spring when new groth appears, remove the dead foliage.

2- Pruning your perennials in fall will allow you to save time in spring. This will also allow you to remove diseased plants and reduce risk of contamination in spring.
Any of these choices will give you great success.

Winter protection

Snow accumulation, dead leaves, mulch and straw are effective ways to protect perennials.

For more information about perennials refer to your garden center.


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