Kansas gardeners might be surprised to learn that not all plants are welcome in the Sunflower State. While many folks enjoy tending to their vegetable patches and flower beds, certain crops are actually against the law to grow.
These restrictions exist for good reasons – from protecting local agriculture to preventing invasive species from taking over Kansas landscapes.
1. Wild Hemp (Cannabis sativa)
Despite hemp’s industrial uses, growing it without proper licensing remains illegal across Kansas. The plant’s similarity to marijuana makes it a controlled substance under state law.
Many Kansas farmers have lobbied for more relaxed regulations, pointing to neighboring states’ successful hemp industries. Unfortunately, backyard enthusiasts caught growing even a single plant face potential fines and legal trouble.
The Kansas Department of Agriculture strictly monitors hemp cultivation, requiring extensive paperwork and background checks for approved growers.
2. Kudzu Vine
Known as “the vine that ate the South,” kudzu is classified as a noxious weed in Kansas. This aggressive climber can grow up to a foot per day during summer months, quickly smothering native plants.
The Kansas Department of Agriculture added kudzu to its prohibited plants list after witnessing the destruction it caused in southern states.
A single kudzu plant in your garden could spread to neighboring properties within weeks. For Kansas gardeners seeking climbing vines, native alternatives like virgin’s bower or trumpet creeper offer similar aesthetic appeal without the ecological risks.
3. Purple Loosestrife
The deceptively beautiful purple flowers make this wetland invader particularly dangerous. Once established in Kansas waterways, purple loosestrife forms dense colonies that choke out native vegetation.
Each plant produces over two million seeds annually, making containment nearly impossible once it escapes garden boundaries. The Kansas legislature specifically banned this plant after it devastated wetland ecosystems throughout the state.
Garden centers once sold purple loosestrife as an ornamental before its destructive nature became apparent. Now, possessing even a single plant can result in significant penalties.
4. Johnson Grass
This seemingly innocent grass has earned its place on Kansas’ noxious weed list due to its aggressive growth habits. Originally introduced as a forage crop, Johnson grass quickly escaped cultivation.
The plant produces cyanide compounds that can poison livestock, a serious concern in agricultural areas across Kansas. Its extensive root system makes complete eradication extremely difficult once established in your yard.
Many unsuspecting gardeners mistake young Johnson grass for corn seedlings until it’s too late. By then, the hardy perennial has already established deep rhizomes throughout the soil.
5. Castor Bean Plant
With its tropical appearance and striking red seed pods, the castor bean plant might seem like an exotic addition to Kansas gardens. However, it contains ricin, one of the world’s most potent natural poisons.
Just a few castor beans can be lethal if ingested, posing a serious risk to children and pets. Kansas authorities have restricted its cultivation due to both safety concerns and its potential use in bioterrorism.
The plant grows surprisingly well in Kansas’ climate, reaching heights of 15 feet in a single season. This rapid growth makes it particularly difficult for authorities to monitor.
6. Giant Hogweed
This massive plant causes severe skin reactions when touched, making it particularly dangerous. Sap from giant hogweed can cause painful blisters and permanent scarring when exposed to sunlight.
Kansas agricultural officials have banned this ornamental due to its public health threat. The plant’s impressive size – growing up to 14 feet tall with 5-foot leaves – makes it tempting for gardeners seeking dramatic landscape elements.
Several Kansas families learned about giant hogweed’s dangers the hard way after children suffered serious burns from innocent contact. Now, state inspectors actively search for and destroy any specimens found.
7. Field Bindweed
The innocent-looking morning glory relative hides a destructive nature beneath its pretty white flowers. Field bindweed’s extensive root system can reach depths of 20 feet, making it nearly impossible to eradicate once established.
Kansas farmers lose millions annually battling this persistent weed in crop fields. The plant’s classification as a noxious weed means homeowners are legally required to remove it if found on their property.
Some garden catalogs still sell ornamental varieties that closely resemble this banned plant. Kansas gardeners should thoroughly research any morning glory relatives before adding them to backyard landscapes.
8. Russian Olive
Despite its drought-tolerance and silvery foliage, Russian olive trees are prohibited in many Kansas counties. These fast-growing trees displace native species along waterways and alter wildlife habitat.
The thorny branches create impenetrable thickets that block access to streams and rivers. Kansas conservation officers actively remove these trees from public lands, and homeowners are discouraged from planting them.
My neighbor had to remove three mature Russian olive trees last year after receiving a notice from the county. The removal cost exceeded $1,200 – an expensive lesson in checking plant restrictions before landscaping.
9. Multiflora Rose
Originally promoted by the Kansas Soil Conservation Service as a “living fence,” multiflora rose quickly became an ecological nightmare. A single plant can produce up to a million seeds annually, which remain viable in soil for decades.
The thorny shrub forms dense thickets that crowd out native vegetation and create impenetrable barriers across Kansas landscapes. Wildlife management areas spend thousands each year attempting to control its spread.
Several Kansas counties now require mandatory removal of multiflora rose when found. Garden centers instead recommend native prairie roses that provide similar benefits without the invasive tendencies.
10. Scotch Thistle
Standing up to 12 feet tall with striking purple flower heads, Scotch thistle makes a dramatic statement in any landscape. Unfortunately, its aggressive nature has earned it a spot on Kansas’ noxious weed list.
The plant’s enormous spiny leaves deter livestock from grazing, effectively reducing usable pasture land across Kansas. Each plant produces thousands of seeds that remain viable for years, creating persistent management challenges.
Kansas ranchers particularly despise this thistle, as it can quickly transform productive grazing land into unusable territory. Even small backyard gardens can become unwitting sources of infestation for surrounding agricultural areas.