Marijuana and Hemp Cross-Pollination is a Budding Concern

Currently, there are almost 500,000 acres of land used for cannabis cultivation. The industry is growing at unprecedented rates. However, some unforeseen drawbacks have presented themselves. Outdoor marijuana farmers are reporting cases of cross-pollination between hemp and marijuana. Cross-pollination reduces the potency of marijuana flowers and it can lead to losses if they do not meet the required concentration of THC and CBD.

In most areas, cannabis growing territories are not categorized into hemp and marijuana zones. Therefore, cases of cross-pollination will keep on rising as more state governments legalize cannabis unless action is taken before it is too late. Cannabis farmers have recorded losses in areas like Washington and Arizona after the crop is compromised by hemp pollen. But how does this happen?

Understanding Cross-Pollination

Cross-pollination refers to the pollination of one variety of plant by another variety. The process creates a new variety of crops that is a crossbreed of the 2 plants. There is a misconception that hemp is the male version of marijuana. The two plants are different, and each has both male and female varieties.

Hemp and marijuana have different compositions of THC and CBD. Apart from that, they also differ in their physical characteristics. Therefore, cross-pollination reduces the potency of the crop for the purpose of cultivation.

Hemp contains a low level of THC (usually below 0.3%) and a high amount of CBD. The plant is mostly cultivated for non-indulgence purposes like making construction materials, ropes, paper, and clothing. Cross-pollination can increase the amount of THC in hemp plants, thus making it psychoactive.

On the other hand, marijuana is mostly cultivated for its psychoactive effects because of the high concentration of THC. Cross-pollination reduces the potency of the plants. Apart from that, the process leads to early and increased seeding, thus reducing the quality of flowers. It is estimated that one male hemp plant a mile away from a marijuana field can cross-pollinate the crop. Therefore, it is quite difficult to know the source of the foreign pollen into a marijuana or hemp field.

Effects of Hemp-Marijuana Cross-pollination

The legal cannabis industry is still in its infancy stage. Therefore, hemp and marijuana farmers should work hand in hand to streamline the cultivation, processing, and distribution of cannabis. According to Michigan State University, the new concern is a threat to the industry and stakeholders should find a solution soon.

A single male flower can produce over 350,000 pollen grains which are easily carried by the wind. Cross-pollination lowers the crop yield and also reduces the size of flowers. When hemp pollen pollinates marijuana, it leads to the early onset of seeds which leads to an inferior crop because the plant is mostly grown for its flowers. Consequently, the alteration of marijuana leads to lower market prices. Apart from that, a study by Meier and Mediavilla indicated that cross-pollination decreased essential oils in hemp by up to 56%.

Most people received the 2018 Farm Bill with excitement, and some of these issues were unforeseen. Farmers are now coming to terms with the fact that there is more to cannabis growing than just seed purity and crop maintenance. There is a dire need for the relevant authorities to implement measures to protect farmers.

USDA Reaction

The United States Department of Agriculture has set aside $500,000 for a study on how cross-pollination problems can be tackled. The government agency funded a Virginia Tech research team to conduct some studies on pollen drift. The objective of the study is to establish how and when pollen travels.

When the research is complete, it will help in the formation of laws that govern distance requirements. It will inform about the safe distance between cultivars meant for fiber, seeds, and flowers. It will also help in understanding the safe distance between male and female plants to avoid contamination of active compounds or reduction in crop quality.

The Virginia Tech team plans to use drones to collect pollen using sensors. The gadgets will collect air samples to establish the concentration and distance travelled of foreign pollen in different areas. Apart from that, the research will also provide information about the impact of chemical drifts on the organic cultivation of cannabis. Organic farmers have raised concerns over potential contamination from neighboring farms that use chemicals like herbicides and pesticides.

What is the Solution to Hemp-Marijuana cross-pollination?

Every new industry faces challenges. The cross-pollination problem is an eye-opener to state and federal departments to formulate regulations that help in the control of cross-pollination. Fortunately, male flowers are not the best option for bees or other insects that help in pollination. Wind is the primary agent of pollination for cannabis. Here are some possible solutions that can help with cross-pollination control.

  1. Crop Isolation

The geographical isolation of cannabis fields to help mitigate cross-pollination is the most straightforward strategy. Experts Estimate that a distance of 10 miles between cannabis farms can help in the reduction of cross-pollination. Although pollen grains can drift beyond the distance, the amount is negligible and will lessen impact to marijuana potency. There are also other factors that affect the distance that pollen grains can travel. Some of these factors include wind speed, humidity, physical barriers, and topography.

2. Greenhouse Cultivation

Growing of cannabis in a controlled environment is an effective method of reducing cross-pollination. However, the strategy is expensive and requires heavy capital investment in large scale cultivation. Greenhouse cannabis cultivation locks out any foreign pollen from getting into contact with the plants.

3. Planting windbreakers

Trees have many uses and we come back to them, again. They help in reducing the amount of pollen that the wind carries from one field to another. Apart from trapping the pollen, trees also reduce the speed of the wind, thus reducing the distance of pollen drift from one crop to another.

4. Overhead Irrigation

Water weighs down pollen grains floating in the air and prevents cross-pollination. However, there is not enough research to indicate the impact that these methods have in mitigating cross-pollination.

5. Plant Feminized Seeds

Planting of single-sex plants can help in the reduction of cross-pollination. However, the process of identifying female seeds can also make cannabis cultivation expensive. You should keep checking and removing any male seeds which are in the crop.


The cross-pollination problem is a new phenomenon in the cannabis industry. The departments in charge should come up with feasible ways of regulating the process without hurting farmers. Cross-pollination control will also reduce losses incurred from low potency marijuana.