Growing Cannabis in Colorado

Colorado, located in the western part of the United States, is notable for its diverse geography and climate, making it a unique location for cultivating cannabis. In 2012, the state passed Amendment 64, which allowed adults aged 21 and older to possess and grow limited amounts of marijuana for personal use. Since then, both recreational and medical cannabis markets have flourished in the state. This article will provide an overview of the regulations and best practices for growing cannabis in Colorado.

Legal Regulations for Cultivating Cannabis in Colorado

Personal Use

In Colorado, adults aged 21 and over are allowed to cultivate up to six marijuana plants per person, with no more than three of these in the flowering stage at any given time. All plants must be grown in an enclosed, locked area, whether indoors or outdoors.

Medical Use

Medical marijuana patients may be allowed to grow more plants if their physician provides a recommendation that it’s necessary for their condition.

Commercial Use

To cultivate cannabis for commercial purposes, growers must acquire a license from the state. The licensing process involves background checks, security measures, and strict adherence to cultivation guidelines set by the state.

Climate and Geography Considerations

Colorado’s diverse climate and geography can impact the growth and yield of cannabis plants. The state experiences a semi-arid to humid continental climate, with areas of alpine and subalpine conditions in the mountains.


Cannabis plants prefer a temperature range of 68-77°F (20-25°C) during the day and a slight drop at night. Colorado’s summer temperatures generally fall within this range, but sudden cold snaps, particularly in the mountains, can be detrimental to outdoor crops.


Much of Colorado is situated at a high altitude, which can lead to lower atmospheric pressure and oxygen levels. This can cause plants to develop differently, often with denser buds and shorter stature.


While Colorado is relatively dry, some parts of the state receive adequate rainfall for outdoor cannabis cultivation. However, most growers will need to employ irrigation methods.

Selecting the Right Cannabis Strains

Given Colorado’s unique climate, selecting suitable strains is vital. Some strains are better adapted to the colder temperatures and shorter growing seasons typical of the state.

Indica Dominant Strains

Generally more resilient to cold and have shorter flowering times, making them ideal for Colorado’s climate. Examples include Northern Lights and Blueberry.

High-altitude Strains

Some strains are specifically bred for growth in high-altitude conditions, such as Durban Poison and Himalayan Gold.

Auto-flowering Strains

These strains automatically switch from vegetative growth to the flowering stage based on age, rather than light conditions. Given Colorado’s shorter summer season, these strains can be beneficial as they typically have a shorter growth cycle.

Best Practices for Cultivating Cannabis in Colorado

Whether growing indoors or outdoors, there are specific best practices to consider for optimal yield and plant health.

Indoor Growing

  • Lighting: Ensure 18-24 hours of light during the vegetative stage and 12 hours during the flowering stage.
  • Ventilation: Good air circulation is crucial. Use oscillating fans to prevent mold and pests and to strengthen stems.
  • Soil & Nutrients: Use well-draining soil and provide appropriate nutrients, adjusting based on the plant’s growth stage.

Outdoor Growing

  • Site Selection: Choose a site with maximum sunlight exposure. South-facing slopes are ideal.
  • Protection: Use greenhouses or cold frames to protect plants from sudden temperature drops.
  • Watering: Ensure consistent moisture levels, particularly during the flowering stage. Overwatering or underwatering can lead to plant stress.

Harvesting and Curing


When trichomes (resinous glands on the plant) are mostly cloudy with some amber, it’s typically the right time to harvest. Ensure plants are not watered for a couple of days before harvesting to facilitate drying.


After trimming and drying the cannabis buds, place them in airtight jars, filling them ¾ full. Open the jars daily for a few minutes to allow moisture to escape and fresh air to enter. This process, which can last several weeks, helps to develop the flavors and aromas of the cannabis, while also preventing mold growth.


Growing cannabis in Colorado, whether for personal or commercial use, requires a clear understanding of both state regulations and the unique environmental challenges the state presents. By selecting the right strains and employing best practices tailored to Colorado’s climate, growers can achieve successful and rewarding harvests. As the state’s cannabis industry continues to evolve, so too will the techniques and knowledge available to cultivators in the region.