Thinking about starting a garden in Minnesota? You might be surprised to learn that not all plants are welcome in the North Star State. Minnesota has specific laws prohibiting certain plants from being grown, even in your own backyard.
These regulations exist to protect local ecosystems, prevent invasive species spread, and safeguard public health.
1. Wild Parsnip: The Deceptive Vegetable
Many gardeners mistake wild parsnip for a harmless relative of carrots and cultivated parsnips. The sap from this plant contains chemicals that make skin extremely sensitive to sunlight.
Contact with the sap followed by sun exposure can cause painful rashes, blisters, and burns that may leave scars. Minnesota considers it a noxious weed, making it illegal to transport, propagate, or sell.
2. Japanese Knotweed: The Unstoppable Invader
Once planted as an ornamental, Japanese knotweed has earned its place on Minnesota’s prohibited invasive species list. Its bamboo-like stems and heart-shaped leaves may look attractive, but don’t be fooled.
This aggressive plant can grow through concrete, damage foundations, and is nearly impossible to eliminate once established. A single fragment can regenerate into a new plant, spreading rapidly through gardens and natural areas.
3. Giant Hogweed: The Dangerous Beauty
Standing up to 15 feet tall with impressive white flower clusters, giant hogweed might tempt gardeners looking for dramatic plants. Don’t touch this monster!
Like wild parsnip, its sap causes severe photodermatitis – painful blisters that can scar. Eye contact can even lead to blindness. Minnesota strictly prohibits growing this federally listed noxious weed, which poses serious public health risks.
4. Palmer Amaranth: The Crop Destroyer
Palmer amaranth might look like an ordinary pigweed, but farmers call it a “superweed” for good reason. A single plant produces up to 500,000 seeds and can grow 2-3 inches daily during summer.
Minnesota designated it a prohibited noxious weed after it began devastating agricultural fields. Growing it intentionally is illegal, and gardeners must report any sightings to prevent its catastrophic spread throughout the state’s valuable farmland.
5. Cannabis: The Complicated Crop
Despite changing laws in many states, growing cannabis in your Minnesota backyard remains illegal without proper medical authorization. The state has a limited medical cannabis program, but home cultivation isn’t permitted.
Recreational growing carries significant legal penalties. Some gardeners mistake industrial hemp (which requires licensing) for legal cannabis. Remember that both plants remain heavily regulated in Minnesota regardless of their popularity elsewhere.
6. Common Barberry: The Tick Magnet
Common barberry’s dense growth and thorny branches once made it a popular hedging plant. Minnesota banned it because it serves as an alternate host for black stem rust, a devastating grain disease.
Even more concerning, research shows these bushes create ideal microhabitats for ticks that carry Lyme disease. The humidity under barberry bushes can be 80% higher than surrounding areas, creating perfect conditions for disease-carrying ticks to thrive.
7. Oriental Bittersweet: The Strangling Vine
Don’t be charmed by oriental bittersweet’s bright orange berries and climbing ability. This aggressive vine literally strangles trees by wrapping tightly around trunks and branches as it grows.
Minnesota prohibits this plant because it can topple mature trees and destroy forest canopies. Many gardeners unknowingly plant it for its attractive fall display, not realizing they’re introducing a woodland killer that’s nearly impossible to control once established.
8. Poppy Plants: The Opium Problem
While common garden poppies are perfectly legal, Papaver somniferum (opium poppy) is federally prohibited. The confusion between legal and illegal poppy varieties leads many Minnesota gardeners into trouble.
Growing opium poppies, even unknowingly for ornamental purposes, violates federal law. The plants contain alkaloids used to produce opium and its derivatives. Seed packets rarely specify the exact species, so gardeners should research carefully before planting any poppy variety.
9. Grecian Foxglove: The Heart-Stopper
With its tall spikes of tubular flowers, Grecian foxglove looks like an innocent ornamental. In reality, it contains powerful cardiac glycosides that can disrupt heart rhythm and prove fatal if consumed.
Minnesota added it to the noxious weed list after it began invading natural areas. Unlike common foxglove found in garden centers, this species spreads aggressively through woodlands and prairies, crowding out native plants while posing significant health risks to humans and livestock.
10. Purple Loosestrife: The Wetland Destroyer
Purple loosestrife’s stunning purple flower spikes once made it a garden favorite. Now it’s one of Minnesota’s most recognizable banned plants after devastating wetlands across the state.
A single plant produces up to 2.7 million seeds annually. Once established in wetlands, it forms impenetrable stands that eliminate habitat for native wildlife. Despite its beauty, growing purple loosestrife in your garden directly threatens Minnesota’s precious water resources.
11. Multiflora Rose: The Thorny Nightmare
Originally promoted for erosion control and living fences, multiflora rose quickly earned its place on Minnesota’s restricted noxious weed list. Each plant produces up to 500,000 seeds that remain viable in soil for 20 years.
Birds spread the seeds widely, creating impenetrable thorny thickets that take over pastures and woodlands. The dense growth forms barriers so thick that native wildlife can’t navigate through them, while the thorns make removal extremely difficult and painful.