CO-Horts Blog

Monday, November 19, 2018

Deicing Impacts on Plants, Dogs, and Sidewalks

Posted by Mark J. Platten, Teller County Extension Director

It is that time of year again where snow and ice become part of the landscape…and covers our sidewalks and driveways.  Colorado Springs was covered in a thick layer of ice this past Saturday evening and, while I enjoy skating in a rink, it’s not appropriate on the sidewalks or roads!  In this post, we’ll be looking at different types of deicers and some considerations on how they might affect plants, animals, and even concrete.

Colorado Springs Ice Storm

Deicers are primarily salt-based products that melts, or prevents, the formation of ice and does so by lowering the freezing point of water and preventing a bond between ice and hardened surfaces. The most problematic element in these salts is chloride, which is a corrosive ion that damages metal and concrete and is toxic to plants.  Here are some common products that you’ll find on the market, courtesy of my cohort Alison O’Connor in a previous post:

Sodium chloride: It’s the most widely available and the cheapest. It doesn’t cause corrosion to concrete, and melts ice best when temperatures are in the 20s. It is the most damaging to plant material. If you use this product, use sparingly and in small amounts
Potassium chloride: Our salty fertilizer friend. It’s expensive and not as widely used as a deicer because of rising costs of fertilizer. Works best when temperatures are above 15 degrees F. Because it’s most commonly used as a fertilizer, it’s relatively safe to apply near plants.
Magnesium chloride: It’s the most common product used on our roadways before storms (applied as a “brine”), because it lowers the freezing point of soon-to-arrive precipitation. It can melt ice down to -15F, which is a nice benefit. If applied in moderate amounts, it’s relatively safe for plants and pets. Its corrosion potential is low, as is its pollutant possibilities.
Calcium magnesium acetate (CMA): It has low corrosion potential, so it’s less damaging to cars, metals, sidewalks and plants. Notice it’s not a chloride product…the “salt” comes from the calcium-magnesium mix and the acetate replaces the chloride.  Plus, it’s biodegradable! Its ice-melting properties are equivalent to traditional deicers, but the cost will make you gasp; it may be 20-30 times as expensive as sodium chloride products. The negatives:  it reacts with and corrodes zinc, so it would affect galvanized steel; it requires more material relative to salt to get comparable ice melting (20-70 percent more by weight); and does not perform as well as chloride-based deicers at temperatures below 25°F during heavy snowfall and freezing rain events.

Dogs and Deicers:

Sodium chloride:  Ingesting a large quantity of sodium chloride can be deadly for dogs; mild ingestion will at least lead to gastrointestinal upset. Salt can also irritate dogs’ paws.

Potassium chloride: Is severely irritating to dogs if ingested.
Magnesium chloride: Sold in crystal and flake form, magnesium chloride is a very popular deicer. It can cause stomach problems if ingested in large amounts, and particularly dangerous for dogs with renal disease who are sensitive to large amounts of magnesium.
Calcium salts (calcium carbonate, calcium chloride, and calcium magnesium acetate): Calcium salts are the most hazardous of all ice melts. Ingestion can cause major gastrointestinal distress, and they are most likely to cause external irritation on skin and paws.
My Dog Henry
“Pet-safe” deicers are typically made with an ingredient called urea. Urea is less toxic than other deicing ingredients, but it can still cause issues if not processed specifically for pet safety. Remember to always check the label; the product should be salt- and chloride-free, and labeled as kid- and pet-safe (if it is not safe for kids, it is not safe for your dog).  Sand and kitty litter are safe for pets as well, and though they don’t melt the ice and snow, they adhere to the ice and make it less slippery and are safe for plants.

Before using any product, clear away as much snow and ice as possible. Get out your shovel and do your best. If heavy snow is predicted, then try to shovel more frequently. Chemical deicers come in various forms—pellets, flakes, and liquids—research shows that pellets from 1/16 inch to 3/16 inch in size work the fastest. Regardless of the type, overuse causes problems. Use only as much as necessary and spread out evenly. Placing deicers in a pile is not a good idea on any level!

Pile of Salt on Sidewalk
Remember, deicing products are not meant to melt all snow and ice but aids you in your removal efforts. Also, consider where you are shoveling the snow.  If you place it downhill from the sidewalk, you don’t have to worry about it creating additional problems as it melts and possibly re-freezes.
Hopefully you feel better informed about your choices and have a safe rest of the winter!

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Thursday, November 15, 2018

Further evidence on the value of planting native plants

by Irene Shonle, Gilpin County

If you didn’t see it, the Smithsonian Magazine recently highlighted a study which was just published in the Proceedings of the National Academy of Sciences last month (Oct 2018) (

The Smithsonian’s headline was catchy: Ecologists have this simple request to homeowners: plant native. In it, they summarized the results of a newly released survey of Carolina chickadee populations in the Washington, D.C., metro area which shows that only when an area (a backyard, park, etc), has a proportion of at least 70% native species, will a native bird such as the chickadee be able to survive.
I didn't have a picture of a chickadee, but here are Pine Grosbeaks and finches as some other examples of native birds

 This is because nonnative plants lack an evolutionary history with native fauna and support insect communities that are less abundant and diverse. Given that 96% of all bird species require soft-bodied insects such as caterpillars in order to rear a clutch of young (6,000-9,000 of them!), this lack of insects can spell doom for birds. 
Hummingbird moth caterpillar on native fireweed

According to the study, “most insectivorous birds are absent or declining in urban areas, yet no study has tested whether nonnative plants impact bird populations via food limitation. We monitored reproduction and survival of Carolina chickadees within residential yards and found that when nonnative plants increased, both insect availability and chickadee population growth declined.”  This meant that Carolina chickadees (Poecile carolinensis) had to switch diets to less preferred prey and produce fewer young, or forgo reproduction in nonnative sites altogether. The findings can be extrapolated to habitats beyond the mid-Atlantic U.S. “The general trend will almost certainly hold true, no matter where you are”.

The lead author, DesirĂ©e Narango, is quoted in the Smithsonian article: “There has been a lot of press lately about drastic insect declines and insectivorous bird declines. We hear a lot in conservation that things are in trouble, and they are. So I think this study is a nice example of something that we can actually do at home to make some positive ecological change.”
Native plant garden at Chatfield Botanic Garden

The researcher’s article ends with a recommendation that, to promote sustainable food webs, urban planners and private landowners should prioritize native plant species.  I love that this is something that we can all do, in our back yards, to help.  How often can you do that?  Get out there and plant some native plants! 
Goldenrod makes an excellent habitat plant

Monday, November 12, 2018

Veteran's Day

                          United States Flag                                                  Today is the day for all of us to say THANK YOU to all that have served to protect us and to keep us free.  And to tell them that we will not forget their service.  Several years ago, I had a Veteran, Steve, take our Master Gardener class.  Though he has many health issues from serving in Vietnam, he manages to work at our Master Gardener desk answering many gardening questions.  The year after he took our class, he started sponsoring other veterans to take the class.  Some have completed the course and volunteer hours, other did not.  This year we had 3 women veterans take the class.  They all carry some "scares" from serving.  But this year I realized that with a gentle tug and words of encouragement and pointing out the positives was enough to help them forge ahead to finish their 50 hours.  I am hopeful that they will continue to volunteer and learn more about gardening.

One of these strong bright women actually works for the VA Hospital.  She asked me if I would be a collaborator to help her receive a grant that would allow her, and our program, to help teach more veterans and to put in a therapy garden.  The hope is to provide a space of healing and that some learn enough skills to acquire a job in the Green Industry.  Steve and I had discussed this idea for several years but just needed the right person and the grant to come along.  The ball is now rolling to fulfill the dream of helping our Veterans through gardening.

We all know that staying more active keeps us healthy longer.  I recently read a report about how just getting people out of the office at lunch and out into the landscape was enough to improve their mood and productivity, in fact even more then someone meditating for the same amount of time.  Gardening provides exercise, mental clarity, healthy food and a sense of community.  Hopefully we will have a way to track how gardening improves Veterans lives and the lives of others.  If this program does well in Grand Junction, imagine the potential at all VAs across our nation.

So today I challenge you to not only thank a Veteran but think about how your love of gardening could help someone, Veteran or not in your community.  Most CSU Extension offices are currently accepting applications for the Master Gardener / Colorado Certified Gardener class.  Here are the benfits of being a Master Gardener:

And again, thank you to all that have served.
Susan Carter, Horticulture and Natural Resource Agent, Tri River Area.

Monday, November 5, 2018

Why Should You Water Your Trees This Winter

Why Should You Water Your Trees This Winter
Posted by: Andie Wommack, Douglas County Extension

2018 was another dry year for Colorado. 66% of the state is still experiencing some level of drought, with 37% in either a D3 (Extreme) or D4 (Exceptional) drought. Agriculture usually feels the effect of drought during the first year of a really bad drought, but the second year is when homeowners will start to feel the consequences of our lack of water. If it looks like we are going to be facing drought conditions again in 2019, you may experience watering restrictions in your neighborhood if you haven’t already. This could mean that you may not have the water available to play catch-up from not watering during a dry winter season.

Watering your landscape throughout the winter is crucial if we are not getting moisture. Trees should be watered ten gallons per inch of trunk diameter at knee height. If we get winter moisture, that amount can be reduced. Water to a depth of 12 inches since the majority of your tree’s roots are in the top 6-24 inches of soil. Ideally your trees should be watered three times in September, and then cut back to once or twice a month October through March. Water young trees that are not established and evergreens twice monthly if possible. A tree takes one year for caliper inch of trunk diameter to establish. If you planted a two-inch tree, you will need to provide extra supplemental water for two years until it can get established.

Most tree roots extend two to four times the diameter of the tree’s crown. A storm that produces one inch of rain provides a little less than 2/3 of a gallon per square foot. A tree with a crown diameter of four feet would have a root system roughly between eight and sixteen feet. If this tree has a 12-foot root system, it would receive about 67 gallons of water with one inch of rain. Keep in mind that one inch of snow does not equal one inch of rain! According to NOAA, on average, thirteen inches of snow equals one inch of rain.

Lack of moisture in the months of October through March can cause damage to the root system of plants which then affects their overall health. Drought stress will begin to appear in late spring and summer when the temperatures begin to rise and precipitation amounts decrease. Stressed plants are also more susceptible to disease and insects.

Make sure that you water on days where the low temperatures will stay above freezing and the daytime temperatures are above 40 degrees. Water earlier in the day so the water has a chance to soak in to the ground before temperatures decrease at night. Disperse the water evenly around the whole tree underneath the canopy and roughly three feet from the trunk.

Your shrubs will also need extra water! A small established shrub that is less than three feet needs five gallons every month from October through March. A large established shrub that is more than six feet needs 18 gallons monthly. Newly planted shrubs require the same amount of water twice a month. Mulching is also a great way to retain moisture around your plants! Keep in mind that if it is dry, your turf will need to be watered as well!

Check out these resources for more information: