A hemp farmer in Kentucky grows a field of cannabis plants. A mile away, another farmer grows a nearly identical-looking field of cannabis plants. One farmer is running a legal agricultural operation worth hundreds of thousands of dollars. The other is risking federal prosecution. The difference between their crops is not the species of plant. It is a single number: 0.3 percent.
The legal distinction between hemp and marijuana is both simpler and more arbitrary than most people realize. Understanding it matters because it determines what products you can legally buy online, what you can grow in your backyard, and what the label on your CBD product actually means.
Quick Answer: What Is the Difference Between Hemp and Marijuana?
Hemp and marijuana are both cannabis plants, specifically Cannabis sativa. The legal distinction in the United States comes entirely from THC content. Under the 2018 Farm Bill, hemp is defined as cannabis containing 0.3 percent or less Delta-9 THC on a dry weight basis. Any cannabis plant with more than 0.3 percent Delta-9 THC is classified as marijuana, remains federally controlled under the Controlled Substances Act, and is subject to state cannabis laws. The 0.3 percent threshold is a legal line, not a biological one. The same plant species, grown differently or selectively bred, can fall on either side of it.
The Biological Reality: One Plant, Many Forms
Cannabis sativa is a single species with extraordinary genetic diversity. It has been selectively bred for thousands of years for different purposes: fiber production, seed oil, medicinal use, and psychoactive effects. The plants that produce high-THC cannabis and the plants grown for industrial fiber are both Cannabis sativa. They look different because they have been bred for different traits over generations, but they are not separate species in any botanical sense.
A hemp plant cultivated for CBD production can look very similar to a marijuana plant cultivated for recreational use. They can even grow next to each other and cross-pollinate. The only reliable way to tell them apart is chemical testing, not visual inspection. This creates real challenges for law enforcement and for farmers whose hemp crops occasionally drift above the legal threshold due to environmental factors or accidental cross-pollination.
The 0.3 Percent Threshold: Where It Came From
The 0.3 percent threshold did not emerge from scientific research on the threshold below which cannabis produces no psychoactive effect. It comes from a 1976 botanical paper by Ernest Small and Arthur Cronquist that proposed using this number as a practical dividing line for taxonomic purposes. Small himself has noted that the threshold was never intended to serve as a legal definition of intoxicating versus non-intoxicating cannabis.
A person consuming hemp products with 0.3 percent THC would need to consume an impractical quantity to experience any psychoactive effect. At 0.5 or 1 percent, the situation becomes more nuanced. The 0.3 percent line is genuinely conservative from a public health standpoint, which is part of why THCA flower, which converts to higher THC on a dry weight basis when heated, has created legal complications that states and the federal government are still working through.
What the 2018 Farm Bill Actually Did
The Agricultural Improvement Act of 2018, known as the Farm Bill, removed hemp from the Schedule I definition in the Controlled Substances Act. This was a significant legal change. It made hemp and hemp-derived products including CBD federally legal to grow, process, and sell, subject to state regulations and USDA oversight. Hemp farmers could now get federal crop insurance and use federal banking services. CBD products derived from compliant hemp could be sold across state lines.
What the Farm Bill did not do was fully resolve the regulatory status of hemp-derived CBD as a food ingredient or dietary supplement. The FDA has consistently maintained that CBD cannot be added to food or sold as a dietary supplement under existing law because it is an active ingredient in an approved drug, Epidiolex. This tension between DEA, USDA, and FDA jurisdiction over hemp-derived products has created the regulatory gray area that the entire hemp CBD industry has been operating in since 2018.
Hemp-Derived Cannabinoids: The Legal Gray Area
The Farm Bill’s hemp definition created an unintended consequence. If hemp is legal and hemp contains CBD, and CBD can be chemically converted to Delta-8 THC through isomerization, then is Delta-8 THC derived from hemp also legal? This argument has supported a multi-billion dollar hemp-derived cannabinoid market selling Delta-8, Delta-10, HHC, THCA, and other products that produce psychoactive effects.
The DEA has pushed back on this interpretation, arguing that synthetically derived cannabinoids including those produced through chemical conversion of CBD are not covered by the Farm Bill’s hemp exemption. States have taken different positions, with some explicitly banning these products and others allowing them under hemp regulations. The THCA flower issue is particularly acute because THCA converts to THC when heated, meaning a product that is technically hemp under the 0.3 percent Delta-9 standard becomes significantly psychoactive when smoked.
The 2024 Farm Bill reauthorization included provisions attempting to close some of these loopholes, particularly around THCA and intoxicating hemp products. The exact outcome of these regulatory changes should be verified against current federal law as it continues to evolve.
Industrial Hemp: What It Is Actually Used For
Beyond CBD, hemp has genuine industrial applications. Hemp fiber is used in textiles, rope, paper, and building materials including hempcrete. Hemp seeds are a nutritious food with a favorable fatty acid profile and are sold as hemp hearts, hemp oil, and hemp protein powder. Hemp hurds, the woody core of the stalk, are used in animal bedding and biomass applications. The industrial hemp market, separate from the CBD and cannabinoid market, represents a meaningful agricultural sector with genuine utility.
How to Know What You Are Buying
For consumers buying CBD or hemp-derived cannabinoid products, the practical takeaway from the hemp versus marijuana distinction is this: a product labeled hemp-derived or CBD must meet the 0.3 percent Delta-9 THC threshold to be sold legally in interstate commerce. Verify this through the Certificate of Analysis published by an independent lab. The COA should show Delta-9 THC at or below 0.3 percent on a dry weight basis for the product to be federally compliant.
Products sold in licensed cannabis dispensaries in legal states are marijuana products regardless of what the label says. They are subject to state cannabis law rather than the Farm Bill hemp definition.
Frequently Asked Questions
Is hemp the same plant as marijuana?
Yes. Both are Cannabis sativa. The legal distinction is based entirely on THC content, not on species. Hemp has 0.3 percent or less Delta-9 THC. Marijuana has more than 0.3 percent Delta-9 THC.
Can hemp get you high?
Products made from compliant hemp with 0.3 percent or less THC will not produce meaningful intoxication at normal serving sizes. Hemp-derived cannabinoid products like Delta-8 made from CBD extracted from hemp can produce psychoactive effects because they contain a different form of THC produced through chemical conversion.
Is CBD from hemp legal in all 50 states?
Federally yes, under the 2018 Farm Bill. However, several states have passed their own restrictions on hemp-derived CBD products. Always check your specific state’s current law.
What is the difference between hemp seed oil and CBD oil?
Hemp seed oil is pressed from hemp seeds and contains no meaningful CBD or THC. It is a nutritious food oil. CBD oil is extracted from hemp flowers and leaves and contains CBD and other cannabinoids. These are completely different products that are often confused because they come from the same plant.
Author: Paul Jernigan covers cannabis law and hemp policy for Ganjly.
Related: Read Ganjly’s guide to what is CBD and what is THCA.
