How to prevent surprise hemp plants from birdseed

A UK resident discovered an illegal hemp plant growing in his backyard that he did not plant and learned that hemp bird seed was likely the culprit.
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Imagine UK resident Barry Thorp’s surprise when he noticed a strange plant growing in his backyard that he didn’t remember planting.(1) He emailed his local horticulture specialist and was doubly surprised to discover that it was a Cannabis Sativa hemp plant — which is illegal to grow in the UK without the proper licensure. He was advised by the horticulture specialist to destroy the plant, but the burning question remained: How on earth did the plant mysteriously pop up there to begin with? How did it even get there in the first place? The simple yet unexpected answer he received: birdseed.

According to a Yahoo! News article by Helena Horton, “denatured, or sterilized, hemp seed is often used in recipes for commercial grade birdseed.”(2) Sometimes live hemp seed makes its way into the batches and, under the right circumstances — i.e. a bird carrying its seed back to the nest and accidentally dropping a live hemp seed over a garden or birds knocking a live seed to the ground in their quest to eat from the feeder — , the hemp seed can take root and grow, shocking the homeowner and the community when it’s discovered.(2)

The denaturing process is pretty common among the seed and seed sales community and the actual steps to keep a seed from sprouting is relatively straight forward: you just apply heat. Hemp seed that’s sold for consumption in stores has to be steam sterilized at 180°F
for at least 15 minutes before it’s cleared to be put on shelves in the USA. That’s also why many hemp oils and other live hemp products advise against cooking with heat at too high of a temperature.

Turns out hemp seed isn’t the only thing that can sprout from bird seed mixtures dropped or knocked to the ground. People with feeders set up in their yards have reported having millet, sunflower, corn, safflower, and other plants pop up in their yards around their feeders. This can be a real hassle if you’re going for a certain look with your flower bed or trying to keep a vegetable garden organized.

Click to see our 12 seeds.
Search carefully and you may spot 12 hemp seeds in this image. Click to see the ones we spotted.

If you have a problem with birdseed fallout and surprise plants in your yard, Melissa King’s article How to Stop Bird Seed From Sprouting suggests the following: picking up the seeds by hand or laying a tarp beneath the feeder for easy clean up, stabilizing the feeder to keep it from swaying in the wind and spilling seeds, purchasing a higher quality birdseed with less filler since birds tend to dig through filler seed to find the highest quality seed, and/or simply asking your local birdseed supply store if they carry a non-sprouting variety of feed.(3)

If you already have a surplus of seeds on hand that you don’t want to waste, but the above options seem like too much work, you have the option to simply sterilize the seeds yourself. You can do this one of two ways before loading your seed into your feeder. Your first option is to place the seed on a cookie sheet in a single layer and bake it in the oven at 140F for 10 minutes. Your second option is to place the birdseed in a paper sack and microwave it for 5 minutes. After either baking or microwaving your birdseed, then load it in the feeder as normal. (3)

Until hemp is legalized for private growth and use in one’s region, it’s best to steer clear of the errant hemp plant, even if it happens completely by accident.


[Click here to read more about Legal Issues involving hemp/cannabis.]

1. Swithinbank, A. (2019) Reader Q&A, BBC Gardener’s World, Sept 2019, p 149, 61 words.
2.Horton, H. (2019, September 24). Bird seed can cause cannabis plants to grow in your garden, BBC Gardener’s World expert warns readers. The Telegraph, Retrieved November 05, 2020, from
3. King, M. (2016, October 07). How to Stop Birdseed From Sprouting. Retrieved November 04, 2020, from


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