Operation Kentucky Bluegrass Eradication!

Posted by Nancy Klasky, CSU Extension, City and County of Broomfield

The title refers to what I’ve been calling the efforts my partner, Jim and I have been doing to transform our four-thousand square foot, corner lot, turf yard into something that I’m pretty passionate about, Xeriscaping. Some people think this mean “Zero-scaping” but it is anything but.  The word xeriscaping comes from the Latin xero, meaning dry and scape meaning landscape or view. There was a trend not long ago where people would remove turf and have a rockscape. The problem with rockscapes is that they are heat sinks. They just absorb the suns heat raising temperatures around your home and aren’t very attractive. They also accumulate organic debris and eventually just become a weed breeding ground that is challenging to manage. I experienced much of this during my many years of landscaping work . Xeriscaping, on the other hand is creating a garden that relies on your natural climate. I live in a neighborhood where daily I hear sprinklers going off and lawns being mowed, including our own.  A good portion of Colorado’s population moved here from parts of the country that receive a lot more annual moisture than we do.  What people need to realize is that Kentucky Bluegrass is aptly named, and is not suitable for the Colorado’s semi-arid climate where the average annual precipitation is 17 inches.  Compare this to Kentucky who receives between 42 and 52 inches of annual precipitation.   

Raised bed garden 

We started removing turf by solarization to put a raised-bed garden in the backyard two years ago. We did this by laying down plastic and weighing it down around the edges and in the middle. This process takes about 1 to 2 months depending on how warm the weather is. We had some black plastic which worked well, but since then I’ve learned that clear plastic is actually more effective.  We then built our raised beds and surrounded them with mulch. We live in Longmont where city residents can go get free mulch at the city’s limb diversion center. This works great for this type of area. We add more every year since mulch breaks down and actually will improve the soil composition over time.  The next area we removed the bluegrass from was the other side of our backyard where we are installing a patio. We opted for the plastic solarization method here too.  These two areas eliminated approximately 1/3 of the grass in our backyard. We converted our sprinkler system to drip lines for our vegetable and flower gardens which greatly reduced our water usage. 

This summer we started working on the front yard. This area faces southeast with no shade. The grass has to go! I was a bit daunted just thinking about starting this endeavor because we live on a hill and our front yard has slopes in two directions. There is a 3 foot grade going up to the house, and another slope that is not quite as steep going down the length on the street side. I was worried about drainage and how we would create level gardens.  This hasn’t stopped me however because I’m determined to be an example of a low-water yard in a sea of thirsty Bluegrass! 

Future pea gravel border garden. 

I had drawn up plans based on the square footage and what we want to do. Like many Colorado neighborhoods we do not have any yard between the street and sidewalk, so the heat from the asphalt and cement make this area even hotter. We have finished a 5 foot wide section bordering the sidewalk where we have created a pea gravel garden. This is what we did. After the grass was sufficiently dead we tilled the area and mixed in good garden soil to around a foot deep. Then we added a rock sand mix to add much needed drainage for this area. The top has a 2 inch layer of pea gravel and some bigger rocks for interest. Our plan is to include the most drought tolerant plants in this space such as Ice plant, hens and chicks, yucca, agave and cactus.  I had some hens and chicks that I’d kept in a plastic container for over a year and they are the first addition to our new space.  Hens and Chicks thrive on neglect and do not like a lot of moisture.

Pea Gravel Garden Completion and next levels on the way!

My objective when planting in the front yard is to use all native and water wise plants. Plant Select© is a non-profit initiative that was started by Colorado State University, Denver Botanical Gardens and horticulturists to find the very best plants for our intermountain and high plains regions. I’ve been inspired by the many Plant Select© plants that the Broomfield Master Gardener Demonstration Garden has.  Another important piece to my planning is to benefit the native pollinator populations, and the best way to do this is by using native plants. There are some great books and guides to Colorado and western native plants, and the Plant Select© website also offers many great plant ideas for our climate.

One last area we have started transforming from turf to garden is an area of the side yard. We have removed a lot of soil from the areas already mentioned and this is another very sunny and hot area where the grass was struggling and had to be removed. I wanted a large space to plant gourds and so we

Future Pumpkin Patch 

cut the grass as short as possible and laid down cardboard. Then we just started piling all that soil we’ve been removing from garden and the patio areas. We capped the sprinkler head which will be changed to a drip line and by next spring we should be ready to plant some pumpkins and other fun autumn gourds!   

So far we have removed around 1,000 square feet of our 4,000 square feet turf yard in the two years since we moved in. We are far from done. My hope is to have three quarters or more of that Kentucky bluegrass gone from our lives and to save thousands of gallons of water every year by eventually having established native and drought tolerant plants surrounding our home.  After that is all said and done maybe I’ll look into replacing whatever grass remains with a buffalo grass alternative to save even more of Colorado’s precious commodity that is water!

For information see:

Colorado Water Wise

Water Wise Landscape Design Steps

Xeriscape Turf Alternatives

Xeriscape Soil Amendments

Learning More About Xeriscaping

A Pesky Invasive That Can be Managed

Posted by: Nancy Klasky, Broomfield County Extension

You may have seen common mullein (Verbascum thapsus) scattered along roadways, mountain canyons, rangelands, or in forests. The tall stalky plant has yellow blooms gathered at the top and large sage-colored leaves at the base. It grows profusely after major disturbances like fire, construction, or flooding. Common mullein is an introduced species and is present in all 50 states and Canada. Originally brought to North America for medicinal purposes, it has been designated a C List Noxious Weed by the Colorado Department of Agriculture, which means it is up to private and public entities to manage. 

I got to learn a lot about mullein after the High Park Fire west of Fort Collins. This lightning- ignited fire started in June of 2012 and due to the hot, dry spring, it burned over 87K acres and destroyed 259 homes before being contained a month later. I worked on land in this area at the time and saw first-hand both the devastating effects of the fire and the renewal of the forest that followed. After all, when occurring naturally, fire is a cleansing process that actually keeps our forests healthy. If left unmanaged, accumulated duff (forest litter) and smaller shrubs and trees can create dense, overgrown forests that can cause cataclysmic wildfires. Some regular burning keeps this in check.

Common mullein before mitigation work.

Tiny seeds find their way into crevice of rocks and form first year rosette. 

The land I worked on is a mixed forest just over 8,000 feet in elevation. It’s primarily ponderosa pine, with some Douglas fir and aspen. Ponderosa pine evolved with the wildfires. Thick bark protects them from destruction by low-intensity fires, and natural loss of lower branches reduces “ladder fuel” that allows fire to climb to the crown of the tree. Much of the surrounding land was turned into a moonscape by the High Park Fire, with 100% mortality of trees and other plants. On the managed land, many ponderosa survived, but most other vegetation was destroyed. This created the ideal environment for common mullein to grow, and boy did it grow. Where once there was an abundance of wildflowers, kinnik-kinnik, and common juniper shrubs, there was now a forest of mullein.

Mullein seeds will survive a fire and can remain viable for 100 years! They may have been in the area for decades, unable to germinate until this disturbance. Worse yet, each of these plants can produce 100,000 to 250,000 seeds per terminal spike. I had my work cut out for me, but I was determined to see this beautiful property restored to its natural state. 

Common mullein is a biennial plant, which means it takes two years to grow to its mature height and bloom. The first-year plant is a basal rosette that stays low to the ground and does not flower. If the plant lives to the next year it will bolt up and bloom. Management techniques that work with this lifecycle are important to stopping the spread of this invasive plant and not exacerbating the problem. 

Last years deadheaded stalks with no new mullein growing!

Like I mentioned mullein likes disturbed ground, so how do you get a plant out of the ground without creating more disturbance? First, you only want to remove the plant if it is a first year rosette. The roots are shallow and usually easy to pull up. It’s important to try and press down the soil as you pull the plant out. Yanking the plant out will give the seeds you know are there a better chance. If the plant has made it to the second year, which was the case with many plants by the time we got to them, you want to cut the bloom off before it starts to dry and drop its seeds. With the help of great groups of volunteers we were able to make many trips to the property to work on the mullein issue. Each year we saw less of the plant come back, and each year we worked to remove what did pop up. With persistence and determination, we saw the native wildflowers, kinnick-kinnick, and juniper shrubs take back what was theirs! The beauty of the restoration is when the native vegetation grows back, that is enough to keep the mullein from growing. There are other management options to consider, but I found the mechanical removal of this plant the best one for this area. 

The property with it's natural vegetation having taken back over.

For more information go to the Colorado Dept. of Ag's page on Common Mullein.