Hemp Cross Pollination | A Frustrating Factor In Growing Cannabis Outdoors

growing cannabis outdoors

Last month we talked about one of the frustrations with growing cannabis outdoors, bud rot. This month, we dive into hemp crop cross contamination. One of the biggest frustrations with outdoor cannabis cultivation is in the potential for cross contamination with nearby hemp crops. While hemp cross pollination can also occur indoors, it’s most prevalent outdoors. Cross pollination can ruin cannabis crops and convert them into hemp in a matter of three plant generations.

The Difference Between Cannabis and Hemp

First, it’s important to know the difference between cannabis and hemp. Cannabis and hemp both come from the same plant, however the growth and use of each is the determining factor:

  • ‘Cannabis’ describes a Cannabis sativa plant that has been bred for its potent glands, known as trichomes. Trichomes contain high amounts of tetrahydrocannabinol (THC), most known for its psychoactive effects.
  • ‘Hemp’ describes a Cannabis sativa plant that contains trace amounts of THC. Hemp is used for more industrial uses, such as fiber for clothing and construction as well as for oils and topical ointments.

While cannabis and hemp are derived from the same plant, the properties of each dictate their usage. For cannabis cultivators, hemp cross pollination means less potent THC percentages, altering the end product and its value.

Hemp Crop Cross Pollination with Cannabis

According to a 2015 report from the Oregon Cannabis Connection, three studies showed a pollen drift across 3 to 7.5 miles. A fourth study showed a pollen drift from hemp crops for 30 miles across the Mediterranean Sea. High winds, responsible for such a drift, can carry pollen and seedlings for miles, contributing to cross pollination for outdoor cannabis growers.

Growing indoors can help reduce the potential for cross pollination due to the air filtrations systems typically in place as well as from cross contamination from seedlings. Although some hemp pollen can still make it through today’s air filtration systems, growing indoors and away from the wind helps decrease the potential for hemp cross pollination and cross contamination.

If your cannabis cultivation operation is located within 10 miles of a hemp crop, it’s wise to both move indoors and invest in a quality air filtration system.



Share this entry


  • EnduraFlex on January 2, 2018 at 9:36 am Reply

    Hi there, its good piece of writing regarding media print,
    we all understand media is a enormous source of facts.

  • Annett on December 17, 2018 at 1:26 am Reply

    Very well written article. It will be valuable to anybody who usess it, including
    yours truly :). Keep doing what you are doing – can’r wait to read more posts.

    • Abbie Testaberg on October 13, 2019 at 4:39 pm

      Thank you and best wishes!

Leave a Comment