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.