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.
Once upon a time, there was a castle guarded by soldiers. Enemies obscured by the trees would sneak close to the castle, so the soldiers reduced the threat by removing the trees. Without the trees, the land filled in with grasses, thyme, and chamomile. Animals began to graze in these new fields, keeping the plants low. The soldiers could see clearly across the land, and the sheep were fat and happy. The castle prospered, and everyone who visited wished their land could be so grand. The other land owners cut down their trees and filled in their land with grasses. The smell from the grazing animals wasn’t ideal, so they brought in men to cut the grasses low instead.
The “green carpet” surrounding the finest castles and estates in the 16th & 17th century became a status symbol, and planted the seed for the sod lawn we’re all familiar with today.
In the United States after WWII, automobile technology and availability took off. With the open road ahead of them, well-to-do folks left the cramped urban conditions of the cities, moving outward to new suburban neighborhoods.
Planners like Frederick Law Olmsted and Abraham Levitt gave the people sprawling neighborhoods, with acres of lush green grass. With the popularity of the 2-day weekend on the rise, homeowners indulged in their green Edens. This ignited a new chapter for the centuries old status symbol of the turf lawn – now repurposed for mini-golf and lawn bowl rather than spying enemy invaders and feeding livestock.
“No single feature of a suburban residential community contributes as much to the charm and beauty of the individual home and the locality as well-kept lawns” – Abraham Levitt
Ingrained into the new vision for the American Dream, well-kept lawns became the golden standard. With an estimated 30 to 40-million acres of the United States serving as an irrigated sod lawn today, this status symbol is butting heads with our resources and priorities.
The cold hard truth about lawns are that they are a water hog, high maintenance (what other non-food-production plants do you cut weekly, fertilize seasonally, and treat with chemicals?!), lawns are a food desert for animals & insects, and they do nothing for our groundwater while the water runoff often pollutes creeks and streams with high nitrogen fertilizers, causing harmful algae blooms. All of that lawn maintenance also creates air pollution and noise pollution from mowers, blowers, and trimmer equipment.
A renovation project where Outdoor Design Group helped our client reduce their turf lawn.
But lawns can be great in the right location!
This is where “active-use” vs. “passive-use” spaces come into play. Lawns can be very durable, and are amazing for active children and pets. Maintaining a lawn to play and entertain on is a lovely idea. Kentucky Bluegrass has been a popular turf choice for decades, but climate suited alternatives like Dog-Tuff Buffalo Grass, Bermuda grass, or “steppable perennial lawns” made up of creeping thyme or clover can serve the same purpose as high-water turf lawns with fewer drawbacks. While choosing the right type of lawn for your environment is a start, reducing the overall amount of lawn is still the key to a progressive and sustainable landscape. Maintaining any type of lawn on the side or front of your house where no-one ever spends their time is wasteful for you, your wallet, and the environment.
Steppable groundcover used with other perennials, step stones and mulch.
Consider ditching the golf-course-quality front-yard peacocking and save that neighborly competitiveness for the holiday light display. Instead, beef up your shrub beds, add some neat planters, and opt for native seed mixes that include drought-tolerant grasses & wildflowers. Keep your lawn only where you will use it, and plant a nice tree just west or south of it to keep it cooler and healthier during hot sunny days.
A front yard filled with a diversity of ornamental grasses, perennials, shrubs, landscape rock and mulch.
This is the official blog of Outdoor Design Group, Colorado Landscape Architects. For more information about our business and our services, click here.
Today’s photo is a recent view of a portion of one street median renovation we designed in Lakewood Colorado. We designed several landscape plans for this renovation project, consisting of many miles of existing street medians in that city, that are slated for renewal. It was an interesting and challenging project to work on, and the city staff were great to work with. We look forward to seeing how these designs grow and flourish over time!
Landscape median in Lakewood, Colorado
Before renovation photo of the same median as above, but with camera looking north.
This is the official blog of Outdoor Design Group, Colorado Landscape Architects. For more information about our business and our services, click here.
It seems that the fields of landscaping and gardening are
full of many timeworn statements that people like to repeat over and over. Some
of these green “rules of thumb” are tried and true, while others may
not be so true.
One landscape stereotype regarding tree growth rates that is being challenged is the old adage that “oak trees grow slowly”. I have heard and read this many times and I have repeated this mantra myself for years. But a study of urban trees in the Denver Metro area, published by the Colorado State Forest Service, got me to rethink that stereotype.
This tree study recorded the growth rates of 19 commonly
planted trees planted in public land in the Denver suburb of Westminster, for
24 years. The authors of the study measured the trunk diameters of the trees in
1992, 2000, 2008, and 2016.
The most eye-opening nugget of information in this report is
that the white oak group of trees (bur, swamp white and English oak) were the
3rd fastest growing trees in the study! They grew faster than green ash,
lindens or honeylocust trees. They even
had the same rate of recorded growth as silver maples, a species often referred
to as a “fast grower.”
Data table from the Colorado State Forest Service’s study “Growth Rates of Common Urban Trees in Westminster, Colorado”. Authors: K.A. Wood and A.M. Poulson
One important take-away from this study for me is the fact
that we should reevaluate what trees seem to be the best for planting in
challenging ecosystems such as the urban/suburban areas of the high plains
where Denver sits. It is worth quoting the State Forest Service report to
emphasize this point:
“Some tree species revealed to be fast or moderate growers in this
study have previously been viewed as slow growers, and they are often passed
over at planting time. However, equating growth rates with vigor can be
misleading, as some of the slower-growing tree types on this list can be the
most adaptable to the area (including hawthorn, hackberry and honeylocust).
Adding newly discovered fast-growing species to the planting palette and
incorporating hardy, slow-growing species will maximize the success of planting
projects and promote species diversity.”
To be clear, it is only one type of oak trees (white oaks)
that exhibited fast growth in the study sample. Red oak was also in the study
and showed slower growth. The authors note this is possibly due to the low pH
of high plains soils.
It very well could be that other types of oak trees grow
slowly too, but we don’t have data for that. Or, perhaps another study may come
along and challenge that, as well.
So, as with many “rule-of-thumb” type
statements, don’t believe it until you have seen some data to back it up.
This is the official blog of Outdoor Design Group, Colorado Landscape Architects. For more information about our business and our services, click here.
It’s summer, which means in Colorado and other surrounding states in the Central Plains/Inter-mountain West region of the country, it is Hail Season!
Earlier in the Summer, the Denver area had several sessions of hail that ripped through gardens and landscapes late one June night. Avid gardens who’d been awakened by the cacophony of thunder, torrential rain and hail that night, sleepily rushed out in the morning to find shredded plants and debris scattered everywhere. I myself had many plants I’d been babying from seed and roots all Spring which were severely torn up by the barrage of hail stones.
This horticultural carnage got me wondering what plants are best at surviving the annual severe weather in our region? As I walked around the yard sadly inspecting the damage, it was easy to see that the native and climate adapted plants fared best from the aerial ice-bullet onslaught. So I thought it might be a good idea to create a list of “hail-proof” (or at least “hail-resistant”) plants. The following list of plants is just a cursory look at some possible plant choices that should be better able to handle hail storms:
Ornamental Grasses:
-Many, many varieties. Some of the hardiest, and easiest to grow in our region are Feather Reed (Calamagrostis spp.), Switch grass (Panicum virgatum), Little Bluestem (Schizachyrium scoparium), and Giant Sacaton (Sporobolus wrightii)
This is the official blog of Outdoor Design Group, Colorado Landscape Architects. For more information about our business and our services, click here.
