Published by City Farmer, Canada's Office of Urban Agriculture


A Healthy Garden is a Healthy Ecosystem

By Egan Davis
April 16, 2003

Egan Davis, Garden Foreman at Park & Tilford Gardens, has been working in the landscape horticulture industry for ten years. Egan is a Journeyman Gardener with additional certification through the Canadian Nursery Landscape Association and the Capilano College Landscape Horticulture Program. He has worked at Park & Tilford Gardens for the last 4 years. Park & Tilford Gardens have not used pesticides in over a decade. The pesticide cabinet inherited from previous management is completely empty. With healthy plant material and no major pest and disease problems, Park & Tilford Gardens is proof that good gardening does not include the use of garden chemical products.

Pest and disease problems in gardens can seem like a mysterious challenge to many gardeners. In order to eliminate these challenges, it is important to understand that gardens are complex ecosystems that are influenced by gardening activities. Practicing good horticulture results in balanced, sustainable garden ecosystems with minimal pest and disease problems.


An ecosystem is defined as an interacting system of living organisms and their environment. It is easy to see how a garden suits this definition. Gardens attract mammals, birds, insects, worms, microorganisms, fungus and bacteria that are in search of food and habitat. All of these organisms influence each other and their environment. Likewise, their environment has an influence on them. In a healthy ecosystem, all components are dependent on each other and exist in harmony. When organisms in our gardens proliferate in unbalanced proportions, disturbing the harmony, we call them pests.

A gardener is a part of the garden ecosystem whose activities have an effect on the environment and the organisms in it. Gardening practices can disturb the harmony in the garden by killing organisms or altering the environment. Any one element removed from an ecosystem affects all other elements. This leads to an imbalance.

Healthy gardens are not sterile

The common practice of meticulously cleaning gardens is not beneficial for the resident organisms. Raking organic litter and leaves out of garden beds removes food and habitat for some birds, insects and microorganisms. This causes other organisms in the garden to become either nonexistent or proliferate in unbalanced proportions.

The Misconception of Fertilizers

Using fertilizers can be undesirable for plants and the environment. Often, plants do not use fertilizer applied to gardens. Soil chemistry is a complicated science. Depending on the pH and the components of soil, many nutrients are chemically inaccessible to plants. Many nutrients are leached into the groundwater, before plants can use them. Plants will luxury feed on the available nutrients supplied by fertilizers. This results in soft, lush growth that is not resistant to pest and disease and more susceptible to environmental stress. Overuse of fertilizer products such as bonemeal can lead to chemical imbalances where other nutrients are made to be unavailable to plants.

Pesticides are bad for you and ...

Pesticides negatively impact garden ecosystems. By killing the targeted pest or other non-targeted beneficial organisms, a food source for beneficial insects and birds is removed. Consequentially, there is in an unbalanced resurgence of the original pest and possibly an outbreak of a new pest previously kept in balance by organisms that are either gone or dead. Chemical pesticides are persistent in the environment and can be translocated up the food chain affecting many non-targeted organisms. On top of all this, pesticides do nothing to correct the fundamental reasons for pest and disease problems.

Soil Improvement

Improving soil is a good way to influence the garden ecosystem. By increasing the depth of soil, there is a larger reservoir for water, which means less irrigation is required, and there is less competition between plants for water. This results in less plant stress and higher resistance to pest and disease. Amending soil with organic matter provides the soil with the ability to use and store air, water and nutrients in a more stable way than using chemical fertilizer. Organic matter also provides food and habitat for beneficial insects and microorganisms. Adding organic matter in the form of mulch adds the benefits of protecting the soil from the sun and the rain as well as reduced weeding.

Watering Practices

Good watering practices will reduce plant stress and improve pest and disease resistance. Frequently watering for short periods of time results in shallow root systems and the garden becomes dependant on irrigation. Watering for longer durations less frequently encourages deep rooting of plants and reduces susceptibility to drought stress.

Ecological Diversity

Increasing the ecological diversity of the garden will ensure a more balanced ecosystem. Planting a variety of plants including deciduous and evergreen trees and shrubs as well as herbaceous plants that flower throughout the season will provide much of the food and habitat required for garden organisms. A variety of plants in a garden will limit the proliferation of any one pest or disease organism. Encouraging biological diversity also includes the toleration of stable levels of pest populations. Remember that by killing insects, one element of the ecosystem is removed and other organisms are in some way affected resulting in an imbalance.

Harmony in the Garden

A healthy and sustainable garden is a balanced ecosystem. Pest and disease problems are an indication that the garden is not in harmony. The best way to solve plant health and pest and disease problems is not by cleaning the garden and applying fertilizers and pesticides. Simple horticultural practices such as soil improvement, effective deep watering and increasing the variety of plant material are the best way to create a stable and healthy garden.

Search Our Site[new]

pointer Return to Contents' Page pointer

Revised April 22, 2003

Published by City Farmer
Canada's Office of Urban Agriculture