Commercially cultivated hemp is skyrocketing in the U.S., thanks to the passage of the 2018 Farm Bill, which removed hemp from the list of controlled substances and legalized its growth. Hemp production can be broken down into three distinct categories: grain, fiber, and the compound cannabidiol (CBD) for consumer usage. Regardless of the hemp you are producing, one thing remains true: you need to manage and minimize the economic impact of hemp insect pests on your crop.

Since hemp has not been cultivated broadly in so long, the crop is considered new again, as is the research into what pests and insects may cause economic harm to the crop and hemp pest management. Hemp, while certainly not invincible, is considered resistant, or at least tolerant, to many diseases and pests. Whether you have an existing hemp farm or are considering stepping into this lucrative industry, having tips and ideas for how best to manage hemp insect pests is important.

1. Knowledge is (Hemp Pest Management) Power

While much is still unknown about hemp and how it resists or is affected by pests, some hemp pests have been identified. But not every pest is an economically impacting pest. The first step in the fight for control of hemp insect pests is understanding if it’s a battle worth fighting.

Another reason to closely monitor and understand pests’ impact on hemp plants is the possible effect on the ability to wholesale cannabis grown for its CBD. While it is not yet fully known or understood, there is a query as to whether hemp insect feeding will increase the level of tetrahydrocannabinol (THC).

This could create a potential issue, as the THC levels must remain below the set threshold of 0.3 percent in dry-weight CBD, as ruled in the 2018 Farm Bill. Elevated THC because of pests could render the harvest unsellable. And if the THC level is above 0.5 percent, not only is the entire crop subject to being destroyed, but a violation will be issued by the USA. Three violations in the course of five years could bar you from growing commercial hemp for five years.

Don’t let hemp insect pests interfere with your options of crops. And while there is a lot not yet fully known, a few pests have been identified as dangerous to a successful hemp crop. Know your enemy.

The corn earworm, Eurasian hemp borer, hemp mite, cannabis aphid, and Japanese beetle have all been deemed an economic threat, damaging to hemp, that should be mitigated.

2. Understand How Pests Cause Damage

Not all hemp insect pests are created equal— and depending on the hemp production you are growing, you should fully understand the risks each pest presents, as well as the necessary pest management approach to use against them.

The Japanese beetle, for example, readily feeds on the hemp flowers and is a potentially significant defoliator. Other beetles, such as flea beetles, seem to present a minor threat to the plants. As such, Japanese beetles are more costly to hemp raised for CBD or CBG yield as opposed to ones raised for their fiber.

It’s also important to fight the battle within your geographic area. While southern corn rootworms have the largest geographic territory, they are predominantly found east of the Rockies. Japanese beetles tend to stay east of the Mississippi.

Grasshoppers, particularly in eastern Colorado, have damaged hemp crops differently from other defoliators by causing extensive damage to the twigs and weakening the stems.

Different pests can also damage the hemp at various stages of its development. For instance, spider mites attack plants in an indoor/greenhouse environment but tend to dissipate when transplanted to the field. The hemp russet mite, on the other hand, can cause widespread damage, regardless of the plants being cultivated indoors or outdoors.


3. Integrated Pest Management (IMP)

Once you have an understanding of the potential pest threats to your crop, based on geography, the kind of hemp you’re growing, and the risks of certain pests’ ability to cause economic harm, you can develop a multi-pronged approach to hemp pest management. Because this is such a new-again industry, integrated pest management for hemp is also new, an ongoing work in progress. But from what we currently know, the following steps will help in your goal of a successful hemp crop.

Prevention: Preventing hemp pests like mites, aphids, borers, and corn earworm is the best and first line of defense. And while you may not be able to prevent all hemp insect pests, there are certainly some tactics you can employ to reduce the likelihood:

Quarantine and inspect new plants before introducing them to the larger crop population.

  • Reduce the desirable habitat of pests by ensuring good drainage.
  • Reduce standing water.
  • Do not plant your hemp field beside a cornfield.
  • Control weeds and overgrown vegetation.

Monitor: Keeping a close eye on your hemp crop and regularly inspecting it will allow you to minimize the impact of pests by voluntarily removing affected plants or treating them quickly to prevent spread.

Natural Predators: Introducing or attracting natural predators such as soldier bugs or lady beetles into your crop can keep hemp pests like aphids in check. Introducing plants like lavender among your hemp plants will attract these “good guys.”

Intervention: If additional help is needed to ward off damaging hemp insect pests, there is good news! The EPA has recently approved ten pesticides for commercial use in cultivating hemp. Nine of these are biopesticides, meaning they are either:

  • Biochemical — Naturally occurring or synthetic versions of naturally occurring substances to control pests.
  • Microbial — Microorganisms that control pests.
  • Plant-incorporated protectants — Pesticides naturally produced by plants, with added genetic material.
  • Biopesticides are derived from natural materials and are considered lower risk than traditional chemical pesticides.

Start Strong, Stay Strong

As the hemp industry continues to grow, more data will be gleaned as to what pests are potentially harmful to which kinds of hemp and in what environments. This ongoing collection of knowledge will lend itself to better hemp pest control and how to maximize hemp profitability.

One of the best things you can do to grow a hearty, robust crop of hemp is to start with a hearty, robust strain of hemp seeds. Want to know more about the right hemp strain for you? Reach out to High Grade Hemp Seed today.

Industrial hemp is traditionally more resistant to diseases and pests than many other cash crops; however, hemp can be susceptible to mold. This is especially true for hemp grown for CBD or CBG. Hemp flower tends to absorb moisture, making it a tempting target for mold. If mold does appear in your hemp crop, it can grow quickly, damaging your plants, lowering your yield, or even ruining your harvest. If you plan on growing industrial hemp, then you need to know how to prevent and treat mold on hemp plants.

A Quick Introduction to Mold

Mold may be an enemy to farmers, but it actually serves a useful purpose in the greater ecosystem. This fungus is made up of countless tiny spores that drift through the air and land on surfaces. Mold is everywhere and can be virtually impossible to completely eliminate. (It even started growing aboard the International Space Station!) Mold spores feed by releasing enzymes that break down organic material, such as plants.

In the wild, mold serves as an important decomposer, breaking down dead plants, animals, and waste and returning those particles back to the soil. In order to grow and thrive, mold needs the right type of environment. The key ingredients that mold loves are:

  • Moisture
  • Humidity
  • Stagnant air
  • Darkness

The best hemp mold prevention strategies focus on depriving mold of the ingredients it needs to thrive.

The Most Common Types of Hemp Mold

So far, scientists and researchers have discovered over 100,000 different types of mold, but you don’t need to be on the lookout for all of them. In fact, many types of mold are harmless or can even be helpful. Instead, farmers should focus on just a handful of mold that can damage hemp plants, including:

Gray Mold

Gray mold often attacks plants through openings or wounds in the plant, though it can also infect healthy plants. The calling card of gray mold is brown or gray-brown spots on wet hemp buds. Also, look for yellow discoloration on stems. Gray mold will destroy hemp flowers, making it unhealthy to smoke.

Powdery Mildew

If you notice that your plants look like they were dusted in white flour, you may have a case of powdery mildew. This type of mold loves hot, humid conditions with little airflow. Look for powdery mildew on the foliage of hemp plants. Aside from powder-like spots on the leaves of plants, also look for yellow-to-brown ascomata.

White Mold

White mold can be distinguished by dark brown lesions on the stems of the hemp plant. Stems with lesions break and shred easily, revealing an unappealing cloud of mycelial growth.

Sooty Mold

As its name implies, sooty mold appears like a fine layer of soot scattered across the leaves of your hemp plant. Sooty mold doesn’t directly feed on a hemp plant. Instead, it eats the leavings of common plant insects, like aphids, leafhoppers, and whiteflies. While sooty mold won’t directly harm hemp plants, it can cover the surface of hemp leaves, disrupting photosynthesis and damaging the overall growth and health of the plant.


Perhaps the scariest hemp mold for any farmer to face, fusarium can strike lightning-quick and destroy an entire hemp crop. Fusarium attacks from below, damaging the root systems of a plant. By the time a farmer notices that their hemp plants are beginning to wilt, it’s often too late. The roots of the plants are already destroyed beyond repair. If a full-blown fusarium infection occurs, there is little a farmer can do to save the crop (which is one reason why hemp crop insurance can be so valuable!).

How to Prevent Mold on Hemp

The best way to prevent hemp mold is to remove the elements that help mold thrive. The easiest way to do this is to grow hemp inside of a greenhouse where you have much more control over the growing environment. Greenhouses can be costly, and not every farmer has the budget or infrastructure to grow their hemp crop indoors. If you don’t have a greenhouse, you can still lower your chances of finding moldy hemp in your field one day.

Here are several hemp mold prevention techniques for greenhouse growers and outdoor crops.

Indoor Hemp Mold Prevention Recommendations

  • Install a hygrometer in your greenhouse to monitor the temperature and humidity of your grow room.
  • Set up an efficient exhaust system within your grow house to keep humidity under control.
  • Install fans in the room to blow above the plants and under them. Good airflow can help prevent mold from getting a foothold onto your plants.
  • Add a dehumidifier to your grow house to eliminate humidity. As your plants reach maturity, they will require more water, where their leaves will release into the air, creating more humid conditions inside the grow house.
  • Replace your HVAC filters on a monthly basis.
  • Install high-efficiency particulate air (HEPA) filters to catch as many mold spores as possible.
  • Use UV lights in your HVAC system to kill off mold spores.
  • If you have the budget, consider installing antimicrobial flooring.
  • Consider defoliating your plants as they reach maturity. Cutting off some of the bottom leaves will increase airflow to your plants and lower humidity levels. Cutting off bottom buds will also allow your plants to redirect their energy to growing larger top buds.
  • Carefully inspect your plants every day and be on the lookout for the most common types of hemp mold.

Outdoor Hemp Mold Prevention Techniques

  • Plant your hemp in a field with the most direct sunlight possible.
  • Give your seeds or starts some space to promote airflow and make it more difficult for mold to infect multiple plants.
  • If you live in an area that gets cold temperatures and rain in the fall, consider purchasing early finishing varietals or autoflower hemp seeds.
  • If a long and heavy rain is predicted, cover your crop with tarps to help prevent water-soaked buds.
  • Set up fans in your field after a rain to dry your plants and create more airflow.
  • Install a drip irrigation system if you have the budget. Drip irrigation feeds water directly to the root systems of the plant, unlike pivot irrigation, which can result in wet leaves and lead to hemp leaf mold.
  • Inspect your fields each day and be on the lookout for moldy hemp.

What to Do If You Spot Mold on Hemp Plants

Mold can attack your hemp plants at any stage of growth or even after the harvest as you dry and cure your hemp, so you must always be vigilant. If you do spot moldy hemp, first identify the scope of the problem. If you notice just a few spots on the leaf of a single plant, you may be able to defoliate that plant and save it. However, if the plant is already deeply infected, then excise the plant and carefully monitor the plants in close proximity to the infected plant. If your plants are wet, use fans to dry them.

If you notice a larger infestation in your crop, your best option might be to eliminate the infected plants and immediately harvest the rest of your crop. This is especially true if your hemp flower is wet and you don’t have the means to dry them.

Be sure to toss any infected hemp buds. Moldy hemp buds aren’t just unpleasant to smoke, they can endanger the health of smokers, especially someone who is immunocompromised. Don’t take that risk!

Choose Hemp Seeds That Are Resistant to Mold

One of the best ways to prevent moldy hemp is to choose hemp seeds strains that are genetically bred to resist mold and other diseases. At High Grade Hemp Seed, we have spent years developing some of the most robust hemp strains available on the market. Contact us today to learn how our seeds can protect your future hemp harvest from mold.

Industrial hemp is, generally, a robust and forgiving crop. Hemp can grow in a range of different environments and even survive in less-than-ideal soil. However, there is one part of the growing process that farmers must give special attention to: irrigation. Farmers who grow hemp for CBD or CBG must take special care to maximize the growth potential of every plant so that the hemp flowers produce the highest amount of CBD- or CBG-rich resin. That requires proper irrigation.

Not sure how to irrigate a hemp field? As with most aspects of farming, different approaches to irrigation can work. In this article, we’ll briefly review the more common types of hemp farm irrigation and look at the specific factors farmers must consider when they devise their hemp irrigation system.

Hemp Irrigation Needs

What does hemp actually need when it comes to irrigation? Farmers in dryer states will be pleased to know that hemp is not a water-hungry crop like cotton, avocados, or almonds. Rather, hemp prefers moist soil that is well-drained and well-aerated. (Learn more about the best soil to grow hemp.) Farmers need to take care not to under-water or over-water hemp plants, which could trigger a stress response in their crop and affect the quality and quantity of their CBD and CBG yields.

How much should farmers water hemp plants? That depends on a variety of factors, starting with the irrigation method a farmer chooses to use. Let’s look at three of the more common hemp farm irrigation options.

Flood Irrigation

Flood irrigation is one of the oldest methods of irrigation. It can also be a low-cost irrigation option if farmers have access to cheap or free water. The U.S. Geological Survey describes flood irrigation as “where the entire surface of the soil is covered by ponded water.” Farmers typically pump or pour water into their hemp field, where it flows around the crops.

The benefit of flood irrigation is that it’s a simple system to construct. Just apply water. However, the drawbacks are notable: Flood irrigation can easily lead to over-watering hemp plants. Wet leaves can promote disease. Finally, flood irrigation is a water-intensive irrigation method, which can be prohibitive in areas with high-cost water.

Pivot Irrigation

Pivot irrigation may be a good option for farmers who already own a pivot system and may not wish to invest in an entirely new irrigation system. With the pivot method, a sprinkler pipe or boom pulls water from a water source and delivers it through a row of hanging sprinklers. The automated pipe slowly rotates, delivering water across a field. The pipe itself is supported by towers that allow the sprinklers to hang over the crops.

Pivot irrigation uses far less water than flood irrigation, and it can also be automated to save time and effort. However, since pivot irrigation delivers water from above, a portion of the water will land on leaves and foliage and won’t make it to the roots of the plants. This system can also lead to wet foliage, which can promote diseases.


Drip Irrigation

By far the most popular and effective method of hemp irrigation is the drip method, also known as micro-irrigation. The beauty of the drip system is that it delivers water directly to the “root zone” of the hemp plants. This can be done in a variety of ways, but typically involves a tube, tape, or flexible pipe that runs along a row of plants and delivers low-pressure water to the base of the plants through numerous holes. Drip irrigation systems can be placed above or below ground.

Drip irrigation offers a variety of benefits, especially when used in combination with plasticulture. It is a highly water-efficient irrigation system because it puts water right where the plants need it. It also keeps leaves dry, which lowers the risk of disease.

Because drip irrigation provides water precisely, there is less of a chance that weeds taking advantage of the water will grow and become a problem. Finally, the drip system can be controlled manually or automatically, depending on the preference of the farmer. The flexibility and efficiency of drip irrigation make it the favorite among hemp farmers.

What to Consider When Building Your Hemp Irrigation Plan

The question of how to irrigate a hemp field is a difficult one to answer, because advice must be tailored to the irrigation method you choose, as well as your climate and soil type. However, as you begin to design your hemp field irrigation plan, here are some important factors to consider.

Know Your Water Source

You can’t water your hemp plants if you don’t have any water! Step one in building your hemp irrigation plan is to establish a reliable water source. That might mean using the municipal water system, drilling wells on your property, or using a nearby natural body of water.

Determine How Much Water You Need

The amount of water you need will depend on the climate of your region, the growth stage of your hemp plants, and your irrigation system. As mentioned, drip irrigation requires the lowest amount of water, but you’ll still need between two to three gallons of water per plant per day during peak growing season.

Just to get an idea of what that means, an acre of 1,500 hemp plants using 2.5 gallons of water per day during peak season on an eight-hour watering cycle will require 78 gallons of water per minute. Before you plant your first hemp seed, make sure you have adequate water for your crops.

Filter Your Water

Your water needs to be filtered even if it comes from a clean source, like a well or from the municipal water supply. If your water comes from a pond, lake, or canal, a good filtering system will be even more crucial. Make sure you install the correct size filter for your irrigation system and check it regularly for functionality.

Determine the Optimal Pressure for Your Water

The right water pressure will allow you to deliver the perfect amount of water to your hemp field. Water pressure is the force of the water’s flow. Measured in pounds per square inch (PSI), water pressure moves water through your irrigation system and onto your plants. Water pressure that is too low won’t have enough force to move through your irrigation equipment. If the water pressure is too high, it could damage your equipment and your crops.

The ideal water pressure for your crop will depend on your irrigation system. Drip irrigation requires relatively low water pressure. For example, a drip tape water system requires a PSI of 8 to 15. Consult your irrigation manufacturer for the ideal water pressure for your system. It may also be a good idea to hire an irrigation installation professional to ensure that your pump, pipes, valves, and water pressure regulator are installed correctly.

Irrigation and Fertilization

Many farmers choose to deliver liquid fertilizer through their irrigation system, including phosphorus, potassium, and nitrogen. The amount of fertilizer and what type of fertilizer you need will depend on your irrigation system and the quality of your soil. The best way to determine the fertilization needs of your hemp crop is to test your soil and test your plants.

How to Create a Hemp Irrigation Plan

Irrigation can make or break your hemp crop, so it’s important to get this step right. Devising the right irrigation plan can be tricky, as it requires customized calculations based on the size and scope of your hemp fields, the quality of your soil, your budget, and your climate.

Many farmers, especially farmers planting hemp for the first time, should consider hiring a professional to assist with irrigation planning. One option is to hire an irrigation consultant who can draw a hemp field layout, determine soil and water requirements, and recommend an irrigation system. Another option is to bring on an irrigation technician who can actually install your irrigation system for you based on your irrigation plan.

A final option is to hire an agronomist. These farming professionals can help you with every aspect of preparing your hemp crop, from sourcing the highest quality hemp seeds to making irrigation system recommendations. While an agronomist won’t install your irrigation system for you, they can design an irrigation plan and provide soil and water tests throughout the growing season. Farmers who want overall guidance and professional insight to improve the chances of a successful crop will probably do best with an agronomist. Farmers who simply need to install an irrigation system or repurpose an existing irrigation system for a hemp crop may prefer to hire an irrigation technician.

Got More Hemp Questions?

How to irrigate a hemp field is an important subject for hemp farmers to understand, but it’s only one part of planting, growing, and harvesting a successful hemp crop. If you have more questions about growing hemp, take a look at our 2020 Hemp Growing Guide. If you have questions specifically about hemp seeds for CBD or CBG, contact our friendly representatives.