CO-Horts Blog

Wednesday, September 24, 2014

I Think I Might have Crabgrass in my Lawn?

Alison O'Connor, CSU horticulture agent in Larimer County

Clumpy, fast-growing tall fescue is often incorrectly called
"crabgrass" by home gardeners

It seems that, whenever a grass growing in a lawn doesn’t look quite “right”, it is labeled as “crabgrass”. In the spring we receive calls and emails about ugly, quick-growing clumps of grass that home gardeners suspect to be crabgrass. It never is. Crabgrass doesn’t even think of germinating until late April or May, since it is a warm-season annual. But people will insist that crabgrass is making a mess of things in their lawns in March and April. They are usually seeing tall fescue, bromegrass and quackgrass – perennial, wide-bladed, cool-season weedy invaders of bluegrass lawns that green up early in the spring. Ironically, people rarely recognize true crabgrass in their lawns when it really does begin growing in July and August. We wrote about crabgrass - the real stuff, and its look-alikes - back in July.

Close-up of tall fescue - often mistaken for crabgrass
In the past few weeks, the cool-season grasses (including the clumpy, ugly ones) are perking up after the heat of August and early September - and home owners are once again seeing “crabgrass” in their lawns. The problem with that is the REAL crabgrass has recently been stunted or killed by cool nights and frost – and is no longer growing in lawns. However, tall fescue, bromegrass and quackgrass are growing happily in response to cool fall temperatures and rain - and people, as in the spring, believe they are seeing "crabgrass" in their lawns.

Crabgrass killed by frost
Even if you have some green, living crabgrass (the real stuff) in your lawn that wasn't hit by that frost on the morning of September 13, it will eventually be killed by frost very soon - so it would be irresponsible (and ineffective) to apply a crabgrass herbicide at this point in the year. But, it’s another story for those nasty patches of quackgrass, brome, or tall fescue. Now is an ideal time to apply glyphosate (aka Roundup…and other brand names of glyphosate products) to control these cool-season perennial grasses. Just remember that glyphosate is non-selective, so anything that it contacts – including bluegrass – will be harmed or killed. Apply glyphosate carefully to patches or clumps of these perennial grasses; apply in the morning when it is calm, and avoid walking where you have sprayed (glyphosate can be tracked onto desirable grass). Wait about 7 days and reapply to control any grasses that were missed or not killed with the first application. When the area is dead, rough up the dead grass with a rake – or use a “foot aerator” to punch holes (the more, the better) in the dead turf. Seed with the appropriate grass (bluegrass or ryegrass into a bluegrass lawn; tall fescue into a tall fescue lawn) and rake lightly to work the seed into the holes. There is no need to topdress with soil or compost. Simply water the spots to keep them moist and you will have new grass growing in the killed area in a few weeks.

So, you might have crabgrass in your lawn - but if it isn't already dead, the next hard frost will kill it. Any ugly, green, happily growing grass you see this in a lawn this time of the year is most likely tall fescue, bromegrass or quackgrass - and it's a good time to control it if you don't want it there next year.

Monday, September 15, 2014

The failed bale experiment. By Irene Shonle, Gilpin County

Try straw bale gardening, they said.  It’s easy, a great way way to overcome poor soils, and anyone can do it, they said.  It’s the next wave of gardening, they said.

Really?  Sounds like it could be a good solution for our mountain gardeners.  Let’s give it a shot!  Since we like to use Extension as a resource whenever possible, we were happy to find several fact sheets on the subject, such as this one from Washington State:

First we bought some bright, shiny bales of straw (this was last year, in 2013).

Then it was time to condition the bales.  We watered the heck out of them and applied nitrogen on days 4-10 as recommended to begin the composting process.   We also wrapped the bales in plastic to help keep in the moisture.

We used a soil thermometer to take the temperature daily, waiting for the spike that indicates the beginning of the compost process.  Nothing happened.  So, we added more water, and more nitrogen.  And kept doing so all summer.  That thermometer didn’t budge. No composting happened at all.  Huh.  Is that even possible?  Apparently, it is.  

We left the bales outside, where we thought the torrential rains of last fall and the winter snows surely would cause some composting.  And this spring, the bales definitely looked more weathered.  Maybe the bales were finally conditioned?

We decided to go ahead and plant,  first adding a layer of compost and potting soil to the bale. We tucked in seeds of nasturtium and swiss chard, envisioning the burst of color and lovely greens.  We watered regularly, and Mother Nature helped us with quite a lot of rain.  We also made sure to fertilize.

How did we do?  Well, here is the sum total of what grew:
Yep. One struggling little chard. And a nasturtium that is so tiny, you can't even see it.

We’re giving up on straw bale gardening. It seems not *everyone* can do it.  Maybe it's our climate.  Maybe it was me.  Has anyone else had success?

Sunday, September 7, 2014

Book Review: A Natural History of North American Trees

Posted by: Eric Hammond, Adams County Extension

 The Book:

A Natural History of North American Trees.  This is an abridged volume which combines two other works; A Natural History of Trees of Eastern and Central North America and A Natural History of Western Trees both of which were originally published in the 1950’s
The Author: 

 Donald Culross Peattie

 Peattie was a well know nature writer in the mid-1900’s who had a particular passion for forestry and silviculture. 


When described in the abstract, this book does not sound terribly exciting.  It is a collection of profiles of North American trees.  For each species the scientific and common names are given followed by a description of the species natural range and then of the plant itself and its uses.   There are any number of other books which are written in a similar way, and unless you are very interested in forestry or a serious tree geek, most of them are a good way to start a nap.   This is what sets Peattie’s book apart.  His descriptions are vivid and he brings in pieces of history and the trees places in it that expand the potential audience to horticulturalists, casual gardeners and even history buffs.  It’s still not the kind of book you pick up and read cover to cover but the descriptions taken on their own or in small groups really are interesting. 
Peattie litters these descriptions with fascinating bits of information and short stories.  For example, he describes how integral the both Utah and single seed junipers (Juniperus osteosperma and J. monosperma respectively) were in the lives of the some of the Native American tribes of the southwest.  He relates how children of some tribes were swaddled in juniper bark “rubbed soft” and placed in cradles made of juniper.  When weaned, they would be fed juniper berries in the fall and winter and warmed by juniper wood burned as fuel.  It was used in many of rites and ceremonies of their lives and its branches were used to sweep away the footprints from around their graves.   Later he relates the story of the famous pioneer botanist David Douglas’s first awkward encounter with sugar pine in the Columbia River Valley.  Sometimes these really are short tidbits as in this single sentence describing why honeyshucks and honey locust were among the common name given to Gleditsia triacanthos the names were “…very appropriate on account of the sweet pods eagerly eaten by cattle and sometimes by nibbling country boys”.    It might just be me but, this made me really curious how the pods taste.  I can’t vouch for the accuracy of the stories but if you are interested in trees or history they are certainly interesting.

Peattie’s writing is often beautiful and sometimes, at least from my 21st century perspective, over the top.  To illustrate, here is his opening paragraph on Utah juniper:

            On the very edge of the opened book of the Grand Canyon – page upon page of red stone tablets receding away into the purple shadows of a billion years of time gone by – perches the Utah Juniper.  Now erect of stem, with crown symmetrically intact, now aslant over the awesome chasm, now storm-torn, broken head, and stem contorted as by the whirl of the winds themselves or lightning-riven and stripped to the white bones of half its bark – this indomitable tree dares the south rim of the cannon for miles.   And when you step gingerly to the edge and look down into the vast emptiness, you see this Juniper far below you, dotting the bridle trail, clinging to perilous ledges, springing out of crevices in the rock, sprinkling the giddy slopes of talus, a symbol of undefeated life in an abyss of death.  From this only silence wells up to you, a silence as of outer and infinite space, where interplanetary gales could blow and make no sound.  But when you stand by a rim Juniper you hear whistling of the wind in its sharp-angled foliage, a high thin vibration of an elemental harp, and it is a comforting sound; it is sort of a message for green life, in all this dead geology.  Yet in its way the living tree, the older and craggier it grows seems the most constant of possible trees in this, the most stupendous site in all the world.

 Oh my, that is a lot of descriptors….   This is typical for the book. They are vivid and express an infectious passion for the natural world but at times are just too much for my tastes.  I found that after reading through a couple they started to run together and so I would only read them in small chunks.   It’s also worth pointing out that from the perspective of a gardener or horticulturalist there is not a lot of information related to these fields in such descriptions. 

The book is filled with charming woodcut illustrations like this one of Utah juniper by Paul Landacre
So should you read this book?   If you are interested in trees and the history of our interaction with the natural world I would guess you will find Pattie’s work interesting and compelling.  If you are looking to read something that will increase your knowledge of horticulture or are partial to precise and concise use of the English language this may not be for you.

Wednesday, September 3, 2014

The Demise of a Demonstration Garden

Posted by Linda McMulkin, CSU Extension-Pueblo County

In August, 2014, the Plant Select demonstration garden at the Colorado State Fair was disassembled and the space returned to its former life as a parking lot.  I’m always sad to lose gardens, but the demise of this garden really hit me hard. 

The four raised beds shortly after the 2006 installation.
In 2005, the Colorado State Fair decided to beautify the Acero Street entrance (Gate 2) to the fairgrounds.  Four raised beds were constructed behind the Fine Arts building using landscape bricks and truly awful soil.  That spring, the beds were planted with a mixture of annuals and perennials by the fair staff and watered by hand.  In the fall, the fair approached CSU Extension and the local Colorado Master Gardeners, offering us the beds for an educational garden.  We agreed and started organizing funds and donations, youth and adult volunteers, and a team to design a garden that was heat tolerant, water wise, and would knock people’s socks off when they came in the VIP Gate. 
By April of 2006, the team was removing perennials from the previous planting; many of those plants were replanted as part of the new design.  Over $1,700 worth of plants, amendments, and mulch were donated by local businesses and Plant Select.  By early summer, spigots were installed for each bed, plants were in the soil, soaker hoses were installed, and wood mulch was spread.  

The garden during the 2010 state fair. 
That was one of the good years.
Over the years, the Colorado Master Gardeners and I spent many hours in those beds, evaluating plant health, planting new species, installing an automatic irrigation system and fixing the leaks, transitioning from wood to pea gravel mulch, picking up trash, pulling weeds, hosting tours, teaching classes, having social gatherings, laughing frequently, and whining a lot.  Like any garden, some years the garden was awesome, some years were a challenge. 

But interest waned as the garden matured.  We got tired and maybe a little bored, the fair seemed less supportive (in their defense, we usually had it under control), the location was out of sight and not ideal for an educational garden, and after several years of agonizing, the volunteers and I decided to turn it over to the fair.  It turns out they were okay with us giving up the garden, as they wanted the space back for staff parking during events.
The bed pictured above during
I was on the fairgrounds the first week of August and learned that the beds were being disassembled.  I hesitated to go watch, but could not resist.  It was painful, but in some ways a relief.  Knowing that the fairgrounds maintenance staff had little time to care for the garden, I expected it to struggle and eventually die.  Now I don’t have to watch it deteriorate over time.

One of the newly planted
 beds near Gate 2
On a positive note, many of the herbaceous plants have been moved to other garden beds on the fairgrounds and 2 previously unfilled beds are now planted.  Although the former garden is again a parking lot, the plants we chose can continue to beautify the Colorado State Fairgrounds.

The volunteers and I learned a lot over the years and mostly enjoyed our experience.  While we mourn the loss of this garden, we help in other public gardens in Pueblo County and continue to scout for a new perfect spot to make our own.

Monday, September 1, 2014

National Ornamental Grass Trials in Colorado

Posted by: Jane Rozum, Douglas County Extension

This time of year, while some perennials are looking a bit tired, there's a perennial that is just starting to put on its best show: Ornamental grasses. I’m not talking the cool-season Calamagrostis (feather reed grass) or Festuca (fescue) species, I’m referring to the beauties born on the Great American prairies, the warm-season Panicum (Switchgrass), and Schizachyrium (Little Bluestem) species.
Warm-season grasses wait until the ground warms in late spring to start growing; these grasses are no fools and would never get caught in a late season frost. They grow best and flower during the warmer months of the year; most start flowering in late July and August. They also have an amazing ability to withstand drought better than their cool-season cousins, making them more than worthy for our low water use landscapes in Colorado.
National Ornamental Grass Trials at Colorado State University
Dr. Mary Meyer from the University of Minnesota launched the National Ornamental Grass Trials in 2012, a three-year study where 17 sites around the country are growing 22 cultivars of warm-season grasses including many cultivars of Panicum (Switchgrass) and Schizachyrium (Little Bluestem). Not only will this study evaluate whether the grasses survive with minimal cultural inputs (horticulture-speak which means that plants don’t use much water or fertilizer), but also look at which plants thrive and possess desirable characteristics making them market-worthy for the nursery industry. Colorado State University is a collaborator in the trials, and 2014 is the second year of data collection for these grasses. At CSU, the grasses have received less than ½ the amount of water a bluegrass lawn would need to grow during the year as well as no fertilizer.

In 2013, the top performers at CSU included: Switchgrass cultivars ‘Shenandoah’, ‘Northwind’, ‘Thundercloud’ and Little Bluestem cultivar ‘Blue Heaven™’. Who will be a top performer this year? We won’t know until the data is collected later this month, but one thing is certain: these tough and beautiful grasses definitely will have a place in future low-water landscapes in Colorado.
Panicum virgatum 'Shenandoah'
P.v. 'Northwind'
S.s 'Blue Heaven'
P.v. 'Thundercloud'

For more information on the National Ornamental Grass Trials, visit the blog @