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Naturalization initiative

Naturalization initiative sign

Naturalization is a program designed to introduce a greater variety of landscapes to our parks. We do this for many reasons: to create new landscapes and designs within our open spaces; to help control weeds, pests, and diseases; to create sustainable landscapes that help support plant, animal and insect life (biodiversity) well suited to Calgary’s climate. Naturalized areas in Calgary will encourage more beneficial and livable parks, with reduced traditional landscaping and long term maintenance costs such as fertilizer, pesticides and irrigation.

Some examples of invasive species targeted through the Naturalization Initiative are:

Smooth brome

Smooth Brome - invasive species
  • Smooth​​ brome is a highly competitive invasive grass which can smother native species and decrease the diversity of native species if not properly managed. Smooth brome is challenging to control because it grows within the same area as our native plants, intertwined among native grasses.
  • There is no single treatment that will control smooth brome.
  • Controlling this species requires repeated applications of herbicide and non-chemical control methods, using adaptive management techniques, which means that control is based on stages of plant growth/maturity rather than based on the calendar year. Smooth brome can germinate under a wide variety of soil, moisture and light conditions, and can stay viable in the soil for up to five years. Each plant can produce 150 to 10,000 seeds every growing season and can also reproduce through spreading underground roots to create new plants; therefore a single treatment may not stop its advance. An abundance of smooth brome may prevent native plants from growing and establishing.

Canada Thistle

Canada Thistle - invasive species
  • This invasive weed is a green leafy weed commonly found in Calgary. It is very hardy and can choke out native vegetation.
  • The best preventive measure is to maintain healthy plant cover with desirable species.
  • Once these weeds are established, killing the roots is the most effective control method, and one of the most efficient ways to accomplish this is with herbicide application. Implementation of an integrated management plan that uses a variety of control options is another effective way to reduce infestations. Fully controlling Canada thistle infestations can take several years. Spending time and effort initially reduces the risk of future infestation and encourages growth of a healthy system which will prevent this weed from overtaking desirable plant species.

Caragana removal

Caragana removal is occurring in the following parks:

For details on this naturalization initiative, please visit our Caragana removal page.


The Naturalization Initiative is a multi-year process that will lead to the establishment of a greater variety of plant communities using native plants that are adapted to Calgary’s climate. The end result will be a more stable and diverse population of drought tolerant, native plants.

Site selection criteria

Prior to beginning the naturalization process within a park, there are several considerations which are evaluated prior to beginning work. The following is a list of questions that are taken into consideration in the decision-making process:

  • Are there areas within the park that are not designated for active recreation?
  • Would this area be suitable for applying alternative landscape techniques?
  • Is this area or part of this area beside a body of water?
  • Is this park or part of this park beside a major or special protection Natural Area?

Frequently Asked Questions

1.Why was this program implemented?

Resources - Parks is seeking efficiencies in service delivery. Because mowing has a significant impact on budget, we are considering areas where mowing patterns or frequency can be modified without impacting park use.

Weed control – Healthy and resilient plant communities are generally the best way to control invasive species. Reintroducing native species can help control invasive species and their detrimental impact. An Integrated Pest Management (IPM) approach is used to manage undesirable species, placing a priority on reduced chemical control of weeds where practical.

Aesthetics - Careful reintroduction of naturalized plants will create visual diversity in the landscape. Wildflowers and ornamental shrubs and trees will add colour and variety to the landscape.

2. Will the use of herbicides increase?

Herbicides are used only when necessary. Each naturalization site will have its own unique need for weed control, and each site is assessed individually in terms of the type and amount of control required. The decision to use herbicides or not is made based on criteria such as the type of weeds, site location and number of weeds on the site.

 The more weeds that can be controlled or eliminated prior to planting native species, the more successful the Naturalization project will be. Controlling weeds prior to planting could take one growing season or more, depending on site characteristics. 

Long term use of herbicides will decrease as a result of Naturalization, as native plant species grow and thrive in Calgary’s climate, providing an environment difficult for invasive plant species to flourish.

3. What does this mean for my community park?

The park sites are chosen based on primary use, location (near natural area, open body of water) and aesthetic value. The naturalization project will not create a situation that will impose on the safety or integrity of the surrounding infrastructure or park users, and may not affect the entire park. Naturalization varies in complexity. Sometimes naturalization is easy, the site has not been too heavily disturbed and a functional habitat rapidly returns. However, in some cases, a greater amount of work may be required to improve the ecological value of the park.

4. Why do we need to naturalize our parks?

This initiative is not a stop mowing initiative; the end goal is to maintain and increase the health of our parks by reducing long term maintenance (fertilizer, pesticides and irrigation). Increasing the biodiversity will help to create a more sustainable landscape. Naturalization is a tool for improving natural weed, pest and disease management, effective naturalization allows for natural response to infrequent, dynamic disturbance events.​​​​​​​​​​​​