Lot Lines – the Official Blog of Outdoor Design Group, Colorado Landscape Architects
When the Grass Grows Taller
Outdoor Design Group is based in Arvada, Colorado – this blog concerns the Great Plains and Western United States. A previous blog post – wonderfully written by Julie O’Brien – traced the origins of the “green carpet”. The ubiquitous American lawn. It’s important to note that the green carpet exists in multiple forms. It’s a literal thing and a cultural construct. Most Americans associate homes with green lawns regardless of the prevailing environmental conditions. The lower 48 of the USA receives between 5” – 120” annual precipitation. Established Kentucky Bluegrass (KBG) requires about 26” of precipitation during the growing season. Our collective perception of the green carpet must incorporate prevailing environmental conditions!
Within the confines of this blog, the term ‘native grass’ refers to grass species found on the Great Plains prior to western settlement; to understand the applicability of native grass, refer to the map below. The eastern half of the United States receives 30 – 70” per year; the western half gets 5-30” (with exceptions in the Pacific NW). Denver sits on the dry half with 15” annual precipitation. Landscape is all about place, and our place is pretty dry. Our native flora have adapted to the prevailing conditions, yet the same cannot be said for the green carpet!
Source: USA Precipitation Map
Sown native grass shines in low-traffic applications. Once established, it needs no supplemental water or fertilizer. It is not soft and fluffy. It needs full sun and doesn’t tolerate heavy foot traffic. If planted in your front yard, there is a high probability that at least one neighbor will vehemently dislike. Yet it’s a solid solution for covering low-use space. After all, you need to do something with any given patch of earth – so weeds don’t run amok. Semi-arid climates such as ours render large-scale KBG nonsensical. It requires excessive irrigation, fertilizer and herbicides, while contributing zero ecological value. Native grass isn’t a silver-bullet; it’s a tool in the toolbox that’s applicable to many areas.
There are myriad factors to consider with native grass. First off, it doesn’t have to be native! Secondly, many species are sold by container. While many viable grass species are endemic to the Great Plains, other well-adapted varieties come from elsewhere in the world. Either way, native grass species have deep roots, grow relatively tall and are not available as rolled sod. They are typically sown by seed, and in some cases installed by plug. It’s difficult to establish and there’s an ongoing maintenance requirement. Ample moisture is required during the first season and an underground sprinkler system is recommended. Temporary (above ground) irrigation can also be used. Weed management is critical. Certain weeds (especially bindweed) must be addressed BEFORE installation! Ongoing weed management will be required! Native grass is not easy. If you’re willing and able, you’ll be rewarded.
There are many cool & warm season grasses to choose from – that differ in terms of height, texture & cold-tolerance. On the shorter side, buffalograss and blue grama are proven options. Taller options include little bluestem, big bluestem, switchgrass, western wheatgrass, sideoats grama & tufted hairgrass – in addition to many more. You might consider several varieties of water-thrifty turf as an alternative to native grass. Options such as Dog Tuff, RTF Tall Fescue & Tahoma 31 Bermudagrass.
This is not an installation guide. Contact your local agricultural extension for more information. Seed suppliers such as Pawnee Buttes and Arkansas Valley Seed are also great resources. Most western residential and commercial landscapes have a place for KBG – the key is scale; not overdoing it. Native grass isn’t for everyone, nor is it perfect for every landscape – yet it’s severely underutilized!
Written by Matthew Whiteman
This is the official blog of Outdoor Design Group, Colorado Landscape Architects. For more information about our business and our services, click here.
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Is this the Beginning of the End for Lawns in the Arid West?
With recent news headlines (https://abcnews.go.com/US/happen-colorado-river-system-recover-historic-drought/story?id=98475953) warning of the extreme drought conditions hitting the western U.S. and the region that makes up the Colorado River basin, cutting water use has become top of mind for many citizens and leaders in Colorado and beyond. One city in Colorado has approved a plan to cut water use in the face of this historic drought, and this plan is raising some eyebrows and generating its own headlines due to its potential impacts.
In the summer of 2022, the city council for Aurora (Colorado’s third largest city), approved restrictions on high water turf lawns for all new construction. Originally proposed by Aurora mayor Mike Coffman, all ten members of the city council voted to approve the new ordinance which limits the amount of turf lawns in new developments and golf courses. (https://www.denverpost.com/2022/08/23/aurora-limits-grass-lawns-golf-courses-water-usage/)
The ordinance prohibits water guzzling turf lawns in common areas, medians, curbside landscape and front yards. In back yards, lawns must be equal to or smaller than 45% of the area, or 500 square feet, whichever is smaller. However, an exception was included to allow front yard turf lawns for residences whose backyards are too small to fit the 45% or 500 square feet threshold.
Perhaps most importantly, the ordinance restricts turf from being used merely for decorative purposes in common areas unless it is for use in “active or programmed recreation areas.” The skinny strips of lawn often found in older commercial developments which are inefficiently irrigated as water over-sprays wastefully on to nearby walks, streets and parking lots, will hopefully become a relic of the past.
Considering that the typical high-water lawn needs 25″ of water annually to look good and green, and Aurora (as well as most of the front-range urban corridor of Colorado) only receives 15″ of natural precipitation all year, reducing or eliminating non-active or un-programmed turf lawns is a very easy way to reduce urban and suburban water use.
This is why another recent headline grabbing story regarding reducing turf lawns was welcome news. In June 2022, the State of Colorado passed a bipartisan-sponsored measure that will encourage property owners across the state to ditch their water-wasting turf lawns (https://leg.colorado.gov/bills/hb22-1151).
The legislation is intended to use state funds ($2 million) to financially incentivize the voluntary replacement of irrigated turf with water-wise landscaping. The bill, HB22-1151, requires the Colorado water conservation board to develop a statewide program that would distribute funds to various “local governments, certain districts, Native American tribes, and nonprofit organizations” for lawn replacement programs. Those funds could then be used to pay property owners to reduce their landscape irrigation by transitioning away from high water turf lawns, towards more climate appropriate landscape treatments. The funds could also go towards expanding some existing programs that already pay property owners to replace water-thirsty lawns, about $1 to $3 per square foot of removed sod. Most of these rebates are only offered in cities in Colorado and not unincorporated areas. One goal of this legislation is to broaden this type of program to other areas in the state.
While $1 to $3 per square foot of removed sod may seem generous, there are reports of some landowners in California getting lawn replacement rebates up to $6/sf. (https://www.cnn.com/2022/08/19/us/california-drought-lawns/index.html). Interestingly, some of the rebate programs in California also require installation of rain barrels as well as turf lawn replacement. That is an intriguing idea for rebate offering entities in Colorado to consider, especially since rain barrels only became officially legal just a few years ago.
Researchers at Colorado State University estimate that landscapes account for at about 55% of the total annual water use for a typical single family home in Colorado.
And most of this goes towards lawn irrigation. In the city of Denver for example, it’s estimated that nearly 25% of the city-wide entire annual water consumption is sprayed on high-water turf lawns. (https://denverite.com/2019/05/06/denverites-can-use-120-million-gallons-a-day-to-water-their-lawns/) Considering that lawns are only irrigated about half of the year or less in Colorado, that is a lot of water that could easily be saved if more lawns were changed into climate appropriate landscape treatments.
Let’s hope that the recent passage of Aurora’s lawn restriction as well as HB22-1151 helps usher in a more water conserving and water conscious future in Colorado and other states in our drought prone region. This won’t translate into a complete disappearance of high-water turf lawns. However, for the sake of our rivers, aquifers and reservoirs, it means that these water-hogging green carpets must be used wisely and judiciously in the designed landscapes of the future.
This is the official blog of Outdoor Design Group, Colorado Landscape Architects. For more information about our business and our services, click here.
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Does the pH of Tap Water Affect your Landscape?
Denver Water customers received news last year that the pH of the water delivered to them by Denver Water would be adjusted from near neutral (pH 7.5) to slightly more alkaline (pH 8.5), which began in Spring 2020.
The motivating reason for this change is for improved human health, which is highly commendable (more alkaline water is less prone to leach lead from pipes into people’s drinking water; lead is toxic to human health).
But, this announcement has many in the Landscape Industry wondering what impacts this may have on irrigating landscape plants, as well as indoor plants, and how it may affect water conveyance equipment (irrigation systems, etc).
A cursory investigation via the internet seems to indicate that the possible impacts from higher pH water on irrigation systems and the plants that receive that more alkaline water are:
- Increased mineral deposits on irrigation equipment as well as pots, planters, etc. For drip emitters this can be very problematic as the water emits at such a low and slow rate that calcium scale build-up could end up clogging the emitters.
- Reduced absorption of minerals and nutrients by the plants.
Most of the soil pH in Colorado’s Front Range are alkaline, so it is possible that this increase in pH will have little or no effect on plants that are already suited or adapted to the native soils of our area. But for plants that don’t do well in alkaline soils, will this more alkaline water be the factor that pushes those plant over the edge? Is this such a bad thing if those plants aren’t suited for our soils (and climate) to begin with?
What are some actions you can take to mitigate the problems of more alkaline water?
- Water more deeply and less often. Frequent and shallow waterings may cause more build-up of salts and minerals like calcium.
- Use alkaline adapted plants in your landscape rather than plants that need acidic soils. Generally speaking, most native plants for our region (Colorado’s eastern Front Range) are well adapted to alkaline soils.
- Check your irrigation equipment for hard water scale build-up. Clean or replace drip emitters that are clogged with scale to ensure proper water flow.
- Add Acidifying materials to the soil, like granules available from garden stores? Some experts seem skeptical of this method, saying it is very difficult to have much impact on the total alkalinity of our native soils.
- Add more organic matter such as compost? Aside from most xeric adapted plants as well as plants native to our region, many of the standard landscape plants benefit from added compost for multiple reasons. Adding compost to soil can lower the pH (more acidic) as well as aid in water retention, soil texture and provide nutrients to plants.
You may wonder if softening your water via chemical means is a good option. Several experts say this is not a good way to lower the pH of the water for plants because softened water has higher salt content, which is also problematic for plant health.
Some articles sourced on the internet mention lowering the pH of the water you irrigate your houseplants with, by adding vinegar. This may work for a small watering can used on houseplants, but for landscape plants this is simply impractical. Could an in-line fertigation system be used with an acidifier such as vinegar on landscapes? We here at ODG are uncertain about this option, but it seems like an intriguing, if also risky, option.
Time will tell how our landscapes react to the increased alkalinity of our water supply. We hope the effect is minimal, because gardening in our high altitude semi-arid climate is challenging enough as is!
This is the official blog of Outdoor Design Group, Colorado Landscape Architects. For more information about our business and our services, click here.