Colorado Mountain Gardener

by Estella Heitman

Oxeye Daisy (Chrysanthemum leucanthemum)

     Every gardening enthusiast has a "pet peeve" or two.  For this gardener, it is the Oxeye Daisy.  This daisy is native to Europe and was introduced to America intentionally as an ornamental and accidentally as a contaminant of imported hay and grain seeds.  It has spread to virtually every state, and in Colorado it is now included on the B List of Noxious Weeds.   Noxious weeds are not just plants out of place; they are non-native plants that are displacing native vegetation and disrupting ecosystems.  List B plants are those for which The Colorado Commissioner of Agriculture, the Colorado Noxious Weed Advisory Committee & local governments are developing and implementing plans to stop the spread of the species.  The greatest impact of the oxeye daisy is on forage production of infested pastures and meadows.  Cattle avoid grazing oxeye daisy.  Dense stands of oxeye daisy decrease plant diversity. 

     These facts are often unknown and/or disregarded by non-professional gardeners - and frequently by property owners who have little interest in gardening but enjoy the vista of acreage covered with these attractive bloomers.  Because the oxeye daisy is such a pretty plant, proper management is often neglected and the plants increase at an alarming rate and compete perniciously with more desirable plant life.  This gardener has, in fact, heard friends and neighbors express great pride in these plants which spread and cover otherwise untended land, requiring little moisture and virtually no care. The oxeye daisy is  often confused with  the Shasta daisy (Leucanthemum x  superbum), a plant that is also a non-native ornamental, although it has a clumping rather than spreading root system and is not considered an invasive plant. 

     The oxeye daisy is a perennial which reproduces primarily by seed, although underground rhizomes contribute to the plant propagation.  Each flower may produce 100 to 250 seeds.  A singly plant may produce up to 26,000 seeds seasonally.  Educational awareness regarding the oxeye daisy and proper management strategies are important for our environment, for our grazing lands, and for the natural beauty of our mountain neighborhoods. For areas with established oxeye daisy invasion recommended controls include mowing as soon as buds appear and continued mowing through the growing season  Hand pulling may be practical for controlling small populations of oxeye daisy, since root systems are shallow and the plant can be dug up and removed.  Herbicides are another option.  Persistent preventative measures may have to be continued for many years since the seeds remain viable in the soil for long periods of time.

Estella Heitman is a Master Gardener who has made her retirement home here in Routt County for the past nine years after many years of part-time residence.  Migrating from the mid-west, she had many, many lessons to learn as a transplanted high-country gardener.  She enjoys the challenges and joys of gardening in the mountains at 8000 feet elevation at her home near Stagecoach Reservoir.