Most exotic garden plants are not particularly problematic.  The majority of garden plants do come from elsewhere in the world.  Some of them, because of their invasive nature, become a serious problem for the well being of native plants when the spread to wild areas.  One of the main ways they escape gardens is as seeds in the belly of birds.  Some of these invasive, noxious plants in the state of Washington are as follows.  Gardeners may be surprised by the inclusion of some of these plants.

Common Fennel, a non-bulbing type that has tall feathery licorice smelling foliage.  Escapees inhabit and colonize grasslands and crowd out native flora.

Purple Verbena, has attractive lavender tubular flowers, is vigorously self seeding and is rapidly spreading into fields and open areas.

Knotweeds, large, bamboo like shrubs with feathery white flower heads.  Bees love them.  The invade riparian areas, block sunlight and degrade habitat for wildlife and fish, including Salmon.  They have very deep roots and a difficult to get rid of.

Old Man's Beard (clematis vitalba), is a climbing vine that when escaped get established in forests and along stream banks where the smother shrubs and trees forming dense mats in the understory.

English Ivy, spreads into forests and forms dense mats that block sunlight, smother trees and encourage rot.  In Western Washington there is a movement to remove English Ivy where ever it exists.

Purple and Garden Loosestrife, are a major threat to wetlands because they tolerate saturated soils and spread rapidly, it crowds out native plants and reduces wetland habitat.

Butterfly Bush, is problematic along rivers and streams where it traps sediment.

These are just a few of the noxious plants that appear in Washington.  Many of them are noxious and invasive in other parts of the country too.  It is a good idea, when planting a garden, to learn about the bad boys of the plant world in your area.  These plants are legal to buy, but they cause serious problems.

Thanks for looking.

David Helm

www.helmhomeinspections.com