CO-Horts Blog

Wednesday, December 30, 2015

Snow Mold in Lawns: Should we be Worried?

Tony Koski, Extension Turf Specialist

The prolonged snow cover for the past few weeks has caused some folks to express concern about snow mold in lawns. While there are a number of snow mold diseases that can occur on turf, the most common one occurring on home lawns is gray snow mold (Typhula incarnata). We blogged about snow mold in lawns a couple of years ago. I won’t repeat what I wrote there – where we covered the basics of snow mold in lawns. Read more here:

Snow mold where snow persisted
along north side of a wood fence.
Gray snow mold is most likely to occur on lawns when the turf has been covered by snow CONTINUOUSLY for 40-60 days. While prolonged snow cover is common on mountain home lawns, it is less common along the Front Range and in other lower elevation regions of Colorado. The Typhula fungus that causes snow mold in lawns is psychrophilic (meaning it grows most happily at temperatures around 32 F). And, like many molds, it enjoys dark, moist (but not frozen) conditions.

While we have some snow on the ground now, it is not a deep snow. And it has been extremely cold, in case you haven’t noticed. The temperatures under the current snow cover are much lower than the optimum for snow mold to flourish – so I wouldn’t be concerned about snow mold in lawns now. 

Snow mold can be more severe on lawns when leaves
aren't mulched or raked in the fall
Even if we get additional snow on top of what is existing, the ground has sufficiently cooled (OK, frozen) to the point that snow mold shouldn’t be a problem in lawns. Snow mold is most severe in years where we receive frequent snows (or long-lasting snow cover) beginning in the fall BEFORE the ground freezes. Deep, long-lasting snow cover on top of unfrozen turf creates perfect conditions for snow mold on turf. Fortunately this combination of conditions is rare along the Front Range (but more common in the mountains). 

Snow mold on dead plant matter in a flower bed.
However, where snow is piled near sidewalks or driveways, or where it persists in shady landscapes or on the north side of homes or fences, snow mold can occur in those parts of the landscape. In the absence of prolonged snow cover, it can also occur on lawns where a layer of wet, matted tree leaves are left over from the fall (thus the importance of mulching or raking fall leaves on lawns). And because it is known as a facultative saprophyte (fancy words meaning it can live on dead plant material, though it prefers living), you can often find snow mold growing on dead plants and accumulated tree leaves in lawns, flowerbeds and vegetable gardens. 

Even in those years when we do see a bit of snow mold in lawns, it rarely is so
The snow mold fungus usually just kills grass
leaves in lawns - not the entire plant; the
turf usually recovers quickly as temperatures warm
in the spring.
severe that it kills the entire grass plant – with damage limited to leaf blades at the top of the plant. The crown is able to produce new shoots as weather warms in the spring to replace those that have been killed by the snow mold fungus.

Thursday, December 24, 2015

Don't Be the Ghost of "Christmas Lazy"

Posted by: Alison O'Connor, Larimer County Extension

[Wince. I realize the title of this blog is a stretch...]
Holiday lights in Old Town Fort Collins
(from CSU Source; photo by Bet Llavador)
I absolutely love seeing holidays lights on homes and trees. When I was younger, mom would drive my brother and me around and we would critique each light display. Mom would classify the displays as "nice" or "cheesy". It's a tradition I continue today.

So while I encourage you to celebrate the season with lights, just remember to take them down on a nice day shortly after the New Year. I know they are a ton of work to put up, but leaving your lights on plants (especially trees) can cause damage.

Remember that trees grow concentrically and add a new layer each season on the outside. I like the metaphor that Ralph Zentz, City of Fort Collins forester, uses: On your first birthday, you receive an ice cream cone (but of course eat all the ice cream and leave the cone). On your second you get another and put it on top of the first. And so on. By the time you're 10, you have 10 ice cream cones and you can look at the "layers" of each one if you flip it over. That's how a tree grows--in layers.
The "layers" in a tree
(photo from
As your trees push new growth in spring, the Christmas lights can cut into the flesh of your trees, causing damage. This is called girdling and will interrupt (or stop) the movement of water and nutrients up and down the trunk. It can kill trees if severe enough. In Extension we often talk about the damage of staking straps--lights can cause the same damage.
A classic example of damage from holiday lights wound around a tree trunk
(photo from The Calgary Herald)
Our trees have a hard enough time in Colorado's climate--so do your trees a favor and remove those lights to prevent stress. Happy Holidays!

P.S. Also, remember to throw out your wreath after the New Year--don't be "that neighbor" who leaves it up until Valentine's Day. It's served its purpose and could be a fire hazard :)

Thursday, December 17, 2015

Discover seasonal indoor plants like never before….

Posted by: Linda Langelo, horticulture agent, Golden Plains Area
Photo courtesy of Longwood Gardens
Let your imagination soar this holiday season.  In the photo above, the floral carpet is actually made from apples. 
Photo courtesy of Longwood Gardens
In the above photo ivy, poinsettias and begonias are used for the red and white in this floral carpet.  

Next there is setting the table for your family and guest’s holiday dinner in the photo below.  Just the right touch for Christmas cheer.
Photo courtesy of Longwood Gardens

Then there is the after dinner stroll……
Photo courtesy of Longwood Gardens
One of the many uses of cyclamen for an indoor display.  So this holiday season, enhance the warmth of your home for family and guests with the plants you love in an imaginative and creative way. 

Longwood Gardens once a private estate owned by Pierre du Pont, and today is an internationally recognized horticultural display garden for the public. If you would like to learn more about Longwood Gardens go to the following link:

The Professional Gardener Program started in 1970 at Longwood Gardens.  I was accepted into this program and begun my first training in the world of horticulture.  A few years after graduating from the program I returned to Longwood Gardens to work and was again privileged to be a part of two seasonal committees: Chrysanthemum and Christmas.  The planning for these displays are discussed and decided years in advance. 

I hope these photos will give you inspiration this holiday season and keep your season joyful and warm.  

Tuesday, December 15, 2015

Winter Watering & Mulching

Posted by: Susan Carter, Tri River Area Extension
Ornamental Pear, newly planted
Fall has rapidly come and gone.  Luckily Western Colorado got some rain before the cold set in allowing plants to go into winter hydrated.  I have noticed some trees around the Grand Valley have really hung onto their leaves that typically don’t this late in the season.  Now some trees like oaks will hold onto their leaves for most of the winter, but I have gotten calls about Cottonwoods still with leaves and have notices a lot of Ornamental Pears and others still green or with some fall color.  My theory is the 80 degree weather we had in October didn’t allow the plants to slow down as they should have.  Slowing down on irrigation in late summer and and fall helps them get ready for winter as well.  We will see in spring, how these trees fair. 

Fastigate Oak, Mesa County Fairgrounds
So the question is, what can I do till then?  Well, keep an eye on the moisture is the best thing to do.  Many plants, especially newly planted and evergreens, struggle with our cold dry winters.  At higher elevations, where snow is deep, it insulates the ground and holds in moisture as well as the temperature.  At lower elevations, the soil conditions can be more extreme freezing, thawing, drying out…  When we only receive an inch or two of snow, that snow just evaporates into our dry air leaving little to none for the plants.  So, about once a month on a warm day when the soil will take moisture, drag out the bucket or hook up a house to the building and water these plants.  Now remember trees do not like their trunks wet and if you think about a tree in the woods, up close to the trunk is not where the rain falls. 
Pine and Arizona Cypress

So make sure you are getting water all the way around the drip edge  (the tips of the branches) of the tree and out and soak early in the day so it can absorb.  See our factsheet on winter watering:

and the Plant Talk: and call your local CSU Extension office if you have other plant questions.  

The other thing you can do to hold in moisture and to help with freeze damage is to add some mulch.  Add several inches of wood mulch or clean leaf litter.  On most plants you want to keep the mulch away from the trunk.  

The one exception for breaking the mulch rules, is here at lower elevations after we have a freeze or two, pile the mulch at the crown of your roses.  This protects the graph union from freezing so hard so you "Don't pull a Huey".  Huey is a common red flowered root stock of roses, so know you know where that saying came from and know why your yellow rose turned red, its the rootstock.  Remove this volcano of mulch from  around the roses in mid April when it starts to warm up.  To all of you humans, hope you keep warm and hydrated this winter as well.  
Happy Holidays.

Friday, December 11, 2015

Holiday Cacti: Will they bloom for Christmas?

Jane Rozum, Douglas County Extension
Last year around this time, I bought 3 small ‘Christmas Cacti’ that were $5 each at the grocery store. They were bright and colorful; just what I needed during the ‘oh so short’ days of December. During the year, the three cacti grew and last month (November), I started noticing flower buds and blooms. But wait! They were supposed to bloom at Christmas! 
I decided to do research on why they didn’t bloom at the same time as last year. Well, come to find out that there is much to know about this great holiday plant.
Holiday cacti hail from tropical rain forest areas in Brazil. This group of ‘jungle cacti’ is in the Cactus family (Cactaceae) even though they look nothing like our western US cacti. People have been growing these plants for the holidays for at least the last 150 years. In fact, these long-lived plants are considered heirlooms in many families and have been passed down through generations.
 There are three distinct types of holiday cacti, which are distinguished by their bloom time and other factors.
Thanksgiving Cacti:

Thanksgiving Cacti flowers and stem segments

Botanical Name: Schlumbergera truncata cultivars
Characteristics: Bloom in late November, have stem segments that have pointed teeth, asymmetrical flowers have bend at ovary, and yellow anthers (pollen bearing end of filament inside flower).  

Christmas Cacti:
Christmas Cactus stem segments
Christmas Cactus bloom

Botanical name: Schlumbergera x buckleyi
Characteristics: Bloom around Christmastime, have stem segments that have rounded teeth, asymmetrical flowers do not bend at ovary, and purplish anthers.

Easter Cacti:
Easter Cactus bloom
Botanical name: Rhipsalidopsis gaerterni
Characteristics: Bloom in April, have stems segments with rounded, scalloped edges and bristle-like hairs at the apex of the stem segments. There flowers look more symmetrical and have golden yellow anthers.

Easter Cactus stem segments on left, Thanksgiving on right
Seeing the holiday cacti together makes it easier to tell the difference between the types. Thanksgiving cacti are the most common, typically because florists can force the bloom time to correspond with pre-Christmas sales.
Whatever type of holiday cacti you choose, care is relatively easy.  Water as needed; they do well when the top inch of soil dries out between watering. More abundant blooms are produced on plants that have a sunny location indoors. They are hardy enough to go outdoors in the summer, but need a semi-shade environment and should be brought indoors before the temperatures drop in the fall. All holiday cacti like to be a bit pot-bound, so repotting every 3 years or so should be fine. Try using a succulent potting mix when repotting, which is a bit courser and allows more air movement through the soil. If you want to make your own potting mix, use 60-80% potting media with 20-40% perlite. Fertilization is best done during spring through late summer with a standard indoor fertilizer mix such as 15-30-15 with trace elements. Fertilization doesn’t encourage bloom, so doesn’t need to be applied during the fall and winter months. Problems usually occur when over or under watered, or from such pests as mealybugs, scale insects, aphids and spidermites. Some cacti may drop unopened flower buds, which may occur from a change in temperature, light or not enough water.
Coaxing a holiday cactus to bloom when desired will take concentrated effort.  Bloom time involves either temperature or photoperiod regulation (the length of dark and light during a 24 hour period). To get the plant to produce flower buds, the following is needed:

·         Bright light during the day time such as an east or south facing window.

·         Continuous darkness of 14 hours per day for six weeks for complete bud set. This necessitates keeping plants in a darkened area without household lighting. As little as 2 hours of inadvertent light during this time can cause the plant to not set buds. Once there are buds on the plant, the photoperiod times are not significant.

·         Nighttime temperatures between 50-59 degrees F will encourage bud set regardless of photoperiod. Daytime temperatures, however, are best kept between 60-68 degrees F for maximum flower production.

Enjoy your holiday cacti, whenever they bloom!

Monday, December 7, 2015

GreenCO Dives Into Colorado Water Plan

Posted By Carol O’Meara, Boulder County Extension
Colorado experienced a watershed moment in 2015, one with ripple effects on the state for generations to come.  On the surface, the Colorado Water Plan approved by Governor Hickenlooper on November 19 is an ambitious road map for managing, conserving, and protecting this vital resource.

But still waters run deep, and if you look closely, you’ll see the plan is designed to help Colorado face climate change, population boom, protect wildlife, keep agriculture vibrant, and support economic growth.  All while preserving our quality of life.  

“Our water picture has changed over the last 10 to 15 years; it’s no longer good enough to just have water law managing our water,” said James Eklund, Director of the Colorado Water Conservation Board, which wrote the plan.  “We’ve had record fires, flooding, and historic drought – the worst we’ve ever measured. We’re warmer by two-degrees; our summers are going to be hotter and our growing season extended.”
With Colorado’s population projected to grow 73-percent by 2050 and a projected shortfall of 560,000 acre-feet of water, Governor Hickenlooper in 2013 ordered the creation of the plan.  The CWCB sought input from water providers, agricultural organizations, environmental groups, the General Assembly, local governments, the business community and the public. 

Among the objectives for closing that gap is landscape water conservation.  “With water being recognized as a major factor for the state's long-term growth, now comes the tough discussions and decisions needed to implement a state water plan that works and delivers the quality of life we all treasure,” said Kristen Fefes, a GreenCO board member (GreenCO is an alliance of seven landscape related associations). 
Landscape water use accounts for 3-percent of state water, which may seem like a drop in the bucket.  But a study commissioned by GreenCO suggests that homeowners reducing over-irrigation by 10 to 20-percent can save 86,500 acre-feet of water over 40 years. 

“Because landscape water use is so visible, it is often the main target – and main solution – for saving water.  But it’s not the only solution. There’s no silver bullet; it’s going to take work on a lot of fronts to conserve water.  We believe that xeriscape and other sustainable landscape practices will continue to gain popularity with Colorado consumers. They’re already a business model for us,” said Fefes.
Education may be the biggest challenge and an area where Fefes hopes the state and local policy makers lean on the Green Industry.  “Landscape water use is complicated and how much to use depends on a variety of factors – soil, sun, slope.  There’s no one answer to ‘how much water does landscape use?’  Industry member have technical knowledge to give customized answers to homeowners.  We can be a big asset for state and local policy makers in education, outreach, and implementation.”

Eklund and Fefes agree that urban landscapes are integral to our quality of life and not expendable.  Its value to mitigating heat islands and reducing pollutant runoff is just as important to sustainability as water conservation.
“The knee-jerk reaction is that we can conserve our way out of this, but we’re looking at all the tentacles into lives that could trip us up,” said Eklund.  “The heat island effect could mean that a person keeps their air conditioning on.  If a person stops watering their lawn and it dies, when it does rain we get all that dirt and pollutants washing off and into the wastewater system where we all pay money to treat it.”

Says Eklund, “We must create a conservation culture, use efficient irrigation, teach our kids that we live in a high desert and water is limited.  People moving here need to know that too and not plan for the lush landscapes they might have had back east.”
The Green Industry is committed to being partners with the CWCB in closing the water gap, said Fefes.  Find tips for how you can conserve by signing up for the ALCC Tip of theWeek .