Friday, July 21, 2017

Weeds, NOT landscape plants, by Todd Hagenbuch

This time of the year, flower gardens throughout the area are in full bloom with all kinds of beautiful foliage.  Some of those flowers are annuals, some perennials.  Some are from seed, others grown from bedding plants, and others gifts from friends or neighbors.  Some are natives, some are introduced, and more importantly, some are actually noxious weeds.

A noxious weed is any weed that has been determined by the State of Colorado to negatively impact or threaten our native or agricultural ecosystems.  Typically a plant that was introduced from Europe, Asia, or Africa, these weeds have abilities to out-compete our native plants, meaning they spread unchecked throughout our landscape.  Unfortunately, many of these plants are still being planted in yards and gardens throughout our area, and are sold by nurseries or seed companies and purchased by unsuspecting homeowners who are looking for spreading, low maintenance plants with attractive flowers.  While that’s exactly what they get, homeowners also get themselves and their neighbors into a mess, not to mention that they are breaking the law by planting these noxious weeds.­
List A noxious weeds need to be eradicated, by law, whenever they are found on any property in order to protect communities and the state as a whole. There are several plants that I see in landscapes that are List A species.  

In our area, Orange hawkweed (Hieracium aurantiacum) is one of the biggest List A offenders. It is believed that this plant was sold and planted by a local Steamboat Springs landscaper for several years in the recent past. The orange flowers are beautiful, but this plant spreads quickly and can invade roadsides, lawns, common areas, and more.

Myrtle spurge (Euphorbia myrsinites) is another common plant in home landscapes that needs to be eradicated.  The leafy plant has yellow-green blooms, which are really small flowers surrounded by petal like bracts.  I see this plant in a yard near my sister-in-law’s house when I visit her and it gives me heartburn whenever I see it.

Purple Loosestrife (Lythrum salicaria) is a perennial plant that is found in our area, especially in wet areas. While it looks a lot like our native fireweed, this bad actor can create millions of seeds per plant and those seeds remain viable for 2-5 years. If you find this one in your yard, you’d better get rid of it quickly!

List B noxious weeds are weeds that need to be controlled to limit spread.  You should control these in a yard situation, too, as they can escape to other areas quickly and cause havoc.

Dame’s Rocket (Hesperis matronalis) is a 4 foot tall plant of purple or lavender colored, 4-petaled flowers. It has been included in many wildflower seed mixes, and tends to escape into pastures, forests, and more.

Scentless chamomile
Oxeye Daisy (Chrysanthemum leucanthemum), not to be confused with the larger Shasta Daisy, is another flower that is sometimes included inappropriately in wildflower mixes and is prevalent in our area, both in landscapes and in pastures.  

Other List B species to be aware of include Common tansy (Tanacetum vulgare) and Scentless chamomile (Matricaria perforata).  Attractive plants on Colorado’s Watch List (plants that are a potential threat to our environment) include Baby’s breath (Gypsophila paniculata), and Yellow flag iris (Iris pseudacorus).  Follow this link for a detailed list with photos:

Knowing what you’re planting in your yard is the first step in helping to halt the spread of noxious weeds. Always check wildflower seed packets before planting and check with your local Extension office to see if something you’re considering planting is actually a noxious weed, or if you need help identifying suspicious plants.  Your neighbors will thank you and you can continue to be a law-abiding citizen.

Todd Hagenbuch is the Agriculture Extension Agent for CSU Routt County Extension.

Thursday, July 6, 2017

Decorative ground cover or weed? A second look by Vicki Barney

Bistop's weed 2016

Last summer I researched a cultivated plant, a pretty groundcover that, in my garden, turned shabby and thirsty looking by August.  (See 2016 photo) Snow-on-the-mountain or bishop’s weed (Aegopodium podagraria) is a nonnative ornamental plant brought by the European settlers to North America that thrives in shady areas, spreads by itself, and inhibits weeds.  Although CSU Extension lists it as a suitable groundcover (, other garden sites have labeled it one of the “worst” garden weeds in perennial flower gardens.  In a previous article, I determined it was a weed, calling it bishop’s weed.  (

My war on bishop’s weed started when I casually dug it up.  Bad idea:  bishop’s weed spreads by underground rhizomes that generate new growth from pieces of root left in the soil.  The resulting dense mat not only looked thirsty and shabby, it threatened newly planted native shrubs.  My next move (after my research) was to trim it to the ground and cover the area with cardboard and compost.  Then I waited.  Surely the cardboard and compost and several feet of winter snow would discourage it.

Bishop's weed today
Well, not quite.  In May, healthy shoots peeked out in the seams of the cardboard, next to a big rock, among other perennials, and was creeping into new areas.  I cut back the new growth and added a layer of mulch.  Chemical annihilation is not an option; the garden is for the pollinators.   I’m now watching to see what happens next.  (See Today photo)
In the meantime, I’ve begun to think that bishop’s weed isn’t such a terrible weed after all.   I’ve noticed beautiful beds around town, dense mats of bluish-green variegated leaves and spikes of small white flowers.   Fellow local gardeners refer to it as snow-on-the-mountain and admit it can be invasive but responds well to barriers. It may need trimming/digging to allow room for other plants and some level of irrigation, depending on the location.  In fact, in the right place (shady, contained, not too dry), it grows quite nicely all summer long and shades out unwanted grasses and weeds.   It is a plant that is shared among neighbors and relatives, often associated with Grandma’s garden and fond memories. 

Bishop's weed in the community
I’ve developed an appreciation for bishop’s weed which, after my failed eradication attempts, I now call snow-on-the-mountain.  The thought of fighting it in my garden over the next several years (a certainty when chemicals are not used) is just too daunting.  It is flourishing everywhere in Steamboat – in the neighbor’s garden, on Yampa Street, in front of the Tread of Pioneers Museum, at the Pine Grove Center  (see Community photo) – so there might be a place for it in my garden after all.  I must remember, though, it can be invasive, aggressive, and quite unattractive over time.  So, rather than strive for complete elimination, I will focus on containment, discouraging growth where it is unwanted or unsightly.  Perhaps I can convince all the pretty, invasive, nonnative plants I’ve inherited to play nicely with the native plants I’ve planted to support the bees and birds and butterflies.

A long time Steamboat resident and casual gardener, Vicky Barney is a member of the Master Gardener Class of 2011.

Harison’s Yellow Rose – an Enduring Pioneer by Melissa Baynes

Harison’s Yellow Rose – an Enduring Pioneer by Melissa Baynes
Rosa x harisonii Rivers [foetida × spinosissima]

Men packed tools, provisions and practical provender, the women; Bibles, quilts and their precious roses.   
They were the keepers of memory, carrying the stories of their old homes
that would become the new traditions of the territory....
With her rose she shared water while crossing the alkali plains. 
In the chill Blue Mountains, curled in a common blanket, she kept her rose from freezing. 
Finally, on that great day of arrival on her donation land claim,
she would plant her rose;  a symbol of determination and endurance. 
Some twenty varieties of roses traveled across the trail... to be planted, watered, cherished and shared.
-excerpt from the book "Hatchet, Hands and Hoe" by Erika Calkins

Although my love of plants leans towards our mountain natives, I love the history and stories behind the Harison Yellow Rose, which can be found growing wild and in gardens throughout our mountain communities.  As you drive through town or the countryside, keep a lookout for a beautiful, yellow rose bush.  If you see one, it is likely a Harison’s Yellow… and here is its story:

This lovely rose got its start in the early 1800s.  Richard and George Harison (father and son lawyers) were amateur rosarians and kept a rose garden at their home in Manhattan.  The son, George, was in poor health so he dedicated much of his time and efforts to his beloved garden.  In this garden, the Harison’s maintained a variety of different species of roses including the Persian Yellow (Rosa foetida) and Scotch Briar (Rosa spinosissima).  The Persian Yellow is a native to Iran, Afghanistan and the northwestern Himalayas whereas the Scotch Briar is native to most of Europe.  And, although to this day, the parentage is little uncertain, most experts agree that the Harison’s Yellow is a result of the chance hybridization between the Persian Yellow and Scotch Briar growing in Harison’s garden.

Once this new rose was “discovered”, the Harison’s gave cuttings to several nurserymen including Thomas Hogg and Williams Nursery, but it was William Robert Prince who was best equipped to propagate and distribute this new rose.  It was first marketed in 1830 and was called Harison’s Yellow.  Over time, however, other names have been attributed to this rose and you may hear it referred to by a number of different names including:

Oregon Trail Rose             Pioneer Rose                    Harison’s Gold
Yellow Rose of TX             Yellow Sweet Briar            Hogg's Yellow
Women’s Gold                  Miners’ Wives’ Gold           Crawford’s Rose

In Prince’s 1846 rose catalog, Harison’s Yellow was described as brilliant and beautiful and “a hot sun makes its blooms expand and lose much of their beauty”.  By the mid-1800s horticulturalists and gardeners were treating Harison’s Yellow synonymously with several other roses thought to come from the same original cuttings (e.g., Double Yellow Harison, Hogg’s Seedling Scotch and Williams’ Double Yellow).  There is still some confusion today regarding Harison’s Yellow, these other hybrids and others that arose around the same time in Britain.  Consequently, there are many forms of what is considered to be Harison’s Yellow – some are closer to the Persian Yellow (brighter yellow and fetid) while others are closer to the Scotch Briar (lighter yellow with a pleasant scent).

Regardless of its parentage, gardeners cherished this rose from the beginning.  When pioneers began moving west, women would take roots of Harison’s Yellow across country with them to their new homes.  Their methods for keeping the rose alive were ingenious.  Some used tin cans, buckets or tea cups to carry their treasured roses in while others used damp cloths, raw potatoes or their skirts.  Pioneer women often wore linsey-woolsey skirts (made of a coarse blend of linen and wool) and they sewed the roots deep into the hems.  And, as they walked through the prairie grasses alongside their covered wagons, the dew would moisten their skirts and keep the roots alive.

Westerners loved their Harison’s Yellow.  These roses had beautiful blooms, were very resilient, had needle-like thorns that fended off the hungriest of longhorns and, once rooted, were impervious to drought and cold.  Today, Harison’s Yellow can be found growing feral along the Oregon Trail and at abandoned mining camps and homesteads throughout Colorado and the West.  In Westminster, there is a specimen outside the Bowles House that was likely planted in 1875 and believed to be the oldest in Colorado.  And, you don’t have to look far to find Harison’s Yellow growing in our own mountain communities.  Specimens found in Clear Creek County are thought to be traced back to Sedalia, MO when the Crawford family (Steamboat Springs founding family) began their trek west in 1873.  Margaret Crawford dug up her roses and packed them in her wagon for their move.  The Crawfords spent time in the Evergreen / Clear Creek County area and planted some of their roses along the way on their journey.  Many others brought Harison’s Yellow during the gold rush days of the 1860s.  Miners planted the rose throughout the Central City area and plants can still be found growing on the hillsides outside both Central City and Black Hawk.  Today, the Central City Opera celebrates the Harison’s Yellow as part of their annual festival at the opening of opera season.

If you see a wild yellow rose growing wild in our mountain communities, it is likely a Harison’s Yellow.  The rose is bushy with upright, arching canes and can reach 8ft tall by 4ft wide.  It has straight, sharp thorns and forms suckers on its own roots.  The flowers are slightly cupped, semi-double and usually bright yellow with 20-25 petals.  Harison’s Yellow blooms most heavily in cool, dry weather with only a single flush of flowers in spring or early summer.  It is very hardy; it tolerates full sun to part shade, cold, drought, poor soils and pests… perfect for our tough mountain environment.  However, if you are thinking of adding a little history to your garden by planting or propagating this rose, beware!  Although it thrives on neglect, it is notoriously difficult to establish.  It is usually cultivated as an own-root plant but you may need to be patient and make several attempts to get it to establish and survive.  If you (or a friend) don’t have a plant to take cuttings from, nursery-grown plants are available at some local nurseries in the Denver area.

Few plants have such an amazing history.  So, if you happen to spot one when you are out and about, take a moment to stop and smell the roses and appreciate the rich lore of the Harison Yellow!  It is truly an enduring pioneer.

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