Growing Cannabis in Ontario

Cannabis, both recreational and medicinal, has become a prominent and legitimate crop in many parts of the world. In Canada, with the passing of the Cannabis Act in 2018, growing cannabis became legal for adults under specific regulations. Ontario, as Canada’s most populous province, has its unique set of guidelines and conditions for cannabis cultivation. This article explores the legal framework, climatic considerations, and best practices for growing cannabis in Ontario.

Legal Regulations for Cannabis Cultivation in Ontario

Adult Personal Use

Following the national Cannabis Act (Bill C-45), adults in Ontario aged 19 and older can cultivate up to four cannabis plants per residence (not per person). It is essential to note that the limit is for the household, regardless of the number of adults living there.

Seed Acquisition

Seeds for planting can be legally purchased from the Ontario Cannabis Store (OCS) or other licensed retailers. It’s crucial to ensure that seeds come from a reputable source, both for quality assurance and legal compliance.

Growing Location

Cannabis plants must be cultivated at the grower’s residence. This means that one cannot plant them in multiple locations or on properties they do not reside in. Also, plants should be shielded from public view. If grown outside, it’s recommended to use barriers or fences.

Selling and Distribution

Selling home-grown cannabis or distributing it without remuneration is illegal unless licensed as a retailer. Sharing with other adults is permitted, but not with minors.

Climatic and Environmental Considerations

Ontario, characterized by its continental climate, experiences cold winters and warm summers. Here are some factors to consider:

Outdoor Growing

Ontario’s growing season, from late May to early October, is suitable for most cannabis varieties. However, it’s essential to select strains that can handle potential early frosts in September. Indica varieties, known for their shorter flowering times, might be more appropriate for the province’s climate than some Sativa strains.

Indoor Growing

Given the extended winter months, many growers in Ontario opt for indoor cultivation. This allows for year-round growing and potentially higher yields, as environmental factors can be meticulously controlled. When growing indoors, considerations include proper ventilation, humidity control, and the use of high-quality grow lights.

Pest Management

Common pests in Ontario that target cannabis include spider mites, aphids, and whiteflies. It’s vital to monitor plants regularly, ensuring they remain pest-free. Using natural predators, like ladybugs, can be an organic solution.

Soil and Nutrient Requirements

Soil Type

Loamy soils, which are well-draining and rich in organic matter, are ideal for cannabis. Ontario’s natural soil can sometimes be clayey, which may require amendments such as perlite or sand to improve drainage.

PH Levels

Cannabis prefers a slightly acidic to neutral pH level, between 6.0 to 7.0. Regularly monitoring and adjusting the soil’s pH is necessary to ensure nutrient availability to the plant.


Cannabis requires primary nutrients (Nitrogen, Phosphorus, and Potassium) and secondary nutrients like calcium and magnesium. It’s essential to adjust nutrient levels based on the plant’s stage of growth. Vegetative stages require more nitrogen, while flowering stages demand more phosphorus.

Harvesting and Curing

Signs of Maturity

For optimal THC levels, it’s crucial to harvest cannabis when it’s mature. Trichomes, tiny resin-filled glands on the buds, change from clear to milky white and then to amber as the plant matures. Checking trichomes with a magnifying glass can help determine the best harvest time.


After harvest, buds should be hung in a dark, cool room with humidity levels around 50% for about a week. Ensuring good air circulation prevents mold growth.


Once dried, buds should be placed in airtight jars, stored in a cool, dark place. This curing process, which can last several weeks to months, allows for the development of full flavor and potency.

Challenges and Community Resources

Despite the straightforward legal framework, growers might face challenges such as plant diseases, unpredictable weather patterns, or concerns about security. Ontario boasts a growing community of cannabis enthusiasts. Joining local growing clubs, participating in workshops, or engaging with online communities can be invaluable resources for novice and seasoned growers alike.


Growing cannabis in Ontario can be a rewarding experience, given the right knowledge and resources. By understanding the province’s legal framework, considering the local climate, and investing in proper care and techniques, cultivators can reap abundant and high-quality yields.