CO-Horts Blog

Thursday, October 27, 2016

What Size Tree Should I Plant?

Alison O'Connor, Larimer County Extension

If they can afford it, people will often plant
very large containerized trees like these red
oaks because their size helps create an
"instant landscape" and quicker shade.
But are these large trees worth the cost?
I was fortunate to attend (and present at) the International Society of Arboriculture (ISA) annual meeting in Fort Worth, Texas in August. You may remember my blog from a couple years ago about research that was done by Hall and Ingram on estimating the carbon footprint of a nursery-grown tree. And I admit that I totally "nerd out" when nursery studies answer questions and solve problems for growers and those of us who buy their plants.

Mike Arnold from Texas A&M University and his fellow researchers Lauren Garcia-Chance, Geoffrey Denny, Sean Carver and Andrew King, recently published an article in the Journal of Arboriculture and Urban Forestry, which Dr. Arnold presented at the meeting in Texas:

"Differential Environments Influence Initial Transplant Establishment Among Tree Species Produced in Five Container Sizes": 42(3): 170-180. Since it's a new article, it's not available to the general public.

The objective of the research was to determine if production container size affects the establishment of different tree species when planted in the landscape. It's a question I get whenever presenting tree planting information: does the size of the tree (or container in which it is growing) matter for establishment and growth? The pros and cons to planting larger trees are:

Trees grown in black plastic containers
often develop circling roots - which can turn into
problematic girdling roots when the tree is planted
in the landscape.
  • Larger plants create an "instant landscape"
  • Quicker increase in property value due to larger, more mature trees
  • More rapid development of shade
  • Less potential for damage by people and animals

  • For the buyer, more expensive than smaller trees
  • For the nursery, more expensive to care for and they take up more space
  • Greater potential for circling/girdling roots after planting in the landscape
  • More difficult and expensive to transport and handle at the planting site
  • Require a larger planting hole
  • Greater potential for transplant shock

Property owners and landscape architects/designers must decide if the pros outweigh the cons. Often it comes down to the fact that many people don't want to wait several years for their landscape to look mature, so there is a big demand for larger trees - in spite of the potential problems they present.

Different size containers used in nursery production (compared to a soda can); image from
The Texas A&M researchers grew identical clones (from cuttings) of three tree species (chaste tree, red maple and bald cypress) in five container sizes (#1, #3, #7, #25 and #45), and then planted them into two different landscapes (College Station, Texas and Starkville, Mississippi). Now before you stop reading because the locations were in the south, stick with me...this is a great study. College Station is considered a seasonally xeric environment. While the location receives about 22" of rain during the growing season, most of it comes in October and very little during the hot summer months. Starkville is mesic. It also receives 22" of rain during the growing season, but the rain is more uniformly distributed in each month. As you would expect, both locations are hot!

For the 3 tree species tested, the Texas A&M researchers
found that smaller containerized trees caught up with larger
trees within 3 years after planting in the landscape
So what did they find? Red maple and bald cypress planted from those small #3 containers exhibited the best growth by the end of the first growing season. All three species grown in the #25 and #45 containers grew poorly after transplanting. Trees grown in the smaller containers established more quickly and grew better than plants grown in the larger containers

Dr. Arnold's presentation continued where the research paper left off...looking at the growth measurements three years after planting and the results were astounding. With the chaste tree, they found that trees planted from a #1 container caught up to those grown in the #45 container in just three years! Holy moly! And the bottom line was that trees planted from #3 and #7 containers recovered more quickly from transplanting and reached establishment sooner than the other sizes.

What this study proved is that, if you plant smaller (and less expensive) plant material and wait a few years, you will realize maximum economic gain and greater visual impact from the smaller plants - and they are less likely to have problems like circling or girdling roots when they are mature trees. But you may have to wait three years for them to catch up with the larger trees. Is the wait worth the benefits? Only you can make that decision!
Smaller container  plants are less expensive for the consumer because
nurseries don't have to care for them for as long as larger plants and
they can move them from the nursery to the buyer sooner.

Tuesday, October 18, 2016

The Home Invasion of the Creepy Crawlies

Sitting here in my Grand Junction office, it doesn’t seem like fall since it is 72 degrees outside although the trees are showing beautiful colors.  But the insects are telling us that it is time to get ready for colder weather.  We have had many samples come into our office the last few weeks.   These insects are just looking for a warm place to rest for the winter and your home seems like a good place to them.  Some of these insects like a large cat-faced spider who was so fat she could hardly walk are pretty cool.  Extension is one of those places that you can find us odd people who actually like bugs.  Miss Cat-face got released into our perennial border.
Cat-faced Spider, Photo by Bob Hammon

These insects include many types of spiders, millipedes, ladybugs, boxelder bugs and other seed bugs among the many others that are looking for a winter home.  Most of these insects can be simply swept or vacuumed up.  Luckily this invasion only lasts a few weeks if you aren’t too creeped out.  But if you want to know other methods to get rid of them Colorado State University has some fact sheets. 
I recently had a gal that had a gal that called and said she had insects that roll up and she called them crunchies because when you step on them they crunch.  Most times we need more of a description than that but that day I actually guessed the right insect and sent her the following factsheet.
Milipedes, Centipedes and Sowbugs and Pillbugs aka Roly-Poly

Pillbug, Photo by Bob Hammon

Milipedes, centipedes, sowbugs and pillbugs primarily eat organic matter that is decaying.  However, the last two years we say some vegetables gardens with high populations of these insects specifically the sowbugs and pillbugs were eating fresh vegetables.  One thing that contributed to this issue was that way too much organic matter had been applied to the garden attracting the insects in high numbers.  Another factor may be the mild winters we have had on the western slope so more insects are making it through the winter.  Maybe too many are getting inside to keep warm.  Sorry, that may give some of you the heebie jeebies.   Told you, some of us Extension people are bug nerds.
Spiders are large and more apparent at this time of year with foliage falling off most plants.  The good news is we have very few spiders that are poisonous to people in Colorado. The most prominent poisonous spider is the Black Widow and luckily she is pretty shy.  She makes a web that is very messy.  And look for the red hour glass on her abdomen to identify her.  Just make sure that you always know where you are reaching.  We had a gal that has an outdoor shower and reached up to open the curtain and something bit her.  When they looked they found a spider. And the squashed the spider before they brought it to us.  By the time I got it to an entomologist on the Front Range, it was too damaged to id with the exception that it was not a Black Widow or Brown Recluse.   Spiders tend to get a bad image but they are great eaters of other unwanted insects so instead of squishing try catching and releasing.  And if you need something identified by one of our offices, please do not kill it by stepping on it.  We need a fresh sample.
Boxelder Bug, Photo by Bob Hammon

Boxelder bugs are red and black insects that are eat the seeds of the Boxelder tree.  The best way to avoid attracting them is to plant a male boxelder tree.  A good cultivar is Acer negundo ‘Sensation’.  The insect is harmless to us accept for the fact that they can get into the house.  See our fact sheet for other ideas.
If you have other insects coming into your house, bring a non-squished sample to your local CSU Extension office for identification.  And don’t get too freaked out, they are just looking for a winter home.  Best bet is to find out where they are coming from.  And put those spiders back outside so they can be around for Halloween. 

Thursday, October 13, 2016

Why CSU’s New Stadium Should be Real Grass – and why it Probably Isn’t

Tony Koski, Extension Turf Specialist

Hughes Stadium turf  (yes, real grass!) in 2002, the night prior to
an epic nationally televised Rams victory over Louisville (36-33). It
WAS the best playing surface in the Mountain West Conference.
This past Monday it was announced that CSU’s freshman sensation quarterback, Collin Hill, suffered a season-ending ACL injury during Saturday’s victory over Utah State (you can read about it here). Why am I writing about this in a blog focused on horticulture? Stick with me, even if you aren’t into sports or aren’t a CSU football fan, and you will hopefully see the connection.

As noted in the article, this was a non-contact injury – meaning that Hill wasn’t injured by being tackled or hit by another player. Quoting CSU coach Mike Bobo: “It was non-contact. He was just planting off his left foot, and it buckled. Tough thing for Collin, tough for our football team.” Just bad luck, right? Football injuries happen – usually the result of a collision with another player, being tackled, being fallen upon, etc. And, yes, injuries happen on both types of field surface – synthetic and natural grass. But does it really matter if football is played on grass or synthetic turf?

A close-up of the old Hughes Stadium natural grass playing surface.
Better than synthetic!
Companies that promote the use of their synthetic turf over natural grass for athletic fields vigorously state that their synthetic surfaces are safer for athletes, less expensive and easier to maintain, that they are environmentally friendly – and that they are “just like real grass” (OK, so why even bother with the comparison, if you are better?). These claims are made during the “sell” to athletic directors, coaches, booster groups, school boards, city councils, etc. The claims (especially about money and cost-savings) make it seem like the decision to use synthetic over real grass is a no-brainer and that it would be irresponsible to spend money on grass fields. These “selling points” work – even on otherwise intelligent people – because there is RARELY anyone present when decisions are made to provide evidence to the contrary: that natural grass MIGHT be a better choice than synthetic for a HOST of legitimate, provable reasons.

It was such a big game that there were 2 Cams
there for some reason? They could (and did!) graze
on the stadium turf then. And it was safer for the
players too!
I will honestly state that synthetic turf, in some situations, is often the VERY BEST playing surface for a school to install. But there are so many times when it can be argued that real grass is the most sensible, common-sense choice. The problem is that decision-makers often don’t ask the right questions (about safety and cost), discount and ignore arguments for using real grass, believe without question what the synthetic companies claim, and often bow to the sentiment that “everyone else is doing it, so we have to because it must be the right thing to do”.  Often, the promise of funding to install synthetic (but ONLY synthetic because that’s what a donor or booster group wants for their team or their coach) overrides any other reasoning to consider grass. Worse still, the decision is often made by a coach – who is both highly unqualified to make such an important decision and is also highly unlikely to still be coaching that team when that synthetic turf needs to be replaced.

I could write an entire blog on cost comparisons of installing, maintaining, and replacing the two types of surfaces – but perhaps some other time. However, if you want to read some very compelling evidence that synthetic often does NOT make financial sense, here is an excellent article in Forbes magazine on the topic entitled “How Taxpayers get Fooled on the Cost of an Artificial Turf Field”. It’s quite lengthy, but compelling and difficult to argue with – unless you are a synthetic turf company that isn’t totally forthcoming on costs of maintenance and replacement. The national Sports Turf Managers Association (STMA) also provides a great comparison of costs to maintain these different playing surfaces. Fodder for a future blog!

More important than cost, however, is safety. Which is safer for football players from an injury perspective: grass or synthetic? Synthetic companies will tie themselves in knots to make synthetic appear safer for athletes than real grass. But what does research say about injuries on these two surfaces?

Divots in a natural grass field act as "circuit breakers" when a player's
foot locks in the turf - giving way so that the ligaments and tendons
in knees and ankles are less likely to.
In a study entitled “The effect of playing surface on the incidence of ACL injuries in National Collegiate Athletic Association American Football”, the authors analyzed the National Collegiate Athletic Association (NCAA) Injury Surveillance System (ISS) men's football ACL injury database from 2004-2005 through 2008-2009 to determine what effects that playing surface might have on ACL injury in NCAA football athletes. They found that the rate of ACL injury on artificial surfaces is 1.39 times higher than the injury rate on grass. Specifically, they found that non-contact injuries occurred more frequently on artificial turf surfaces (44.29%) than on natural grass (36.12%), and concluded that “NCAA football players experience a greater number of ACL injuries when playing on artificial surfaces.” This begs the very simple question: why install a playing surface (when you have a choice) that is PROVEN to increase the potential for injury to student athletes?

In a similar study that examined injury rate in NFL players (An analysis of specific lower extremity injury rates on grass and FieldTurf playing surfaces in National Football League Games: 2000-2009 seasons), the authors found that “the observed injury rates of ACL sprains and eversion ankle sprains on FieldTurf surfaces were 67% (P < .001) and 31% (P < .001) higher than on grass surfaces and were statistically significant”. No comment needed on these numbers, as they speak for themselves! (FieldTurf is a specific brand of synthetic turf, and is what is currently installed in Hughes Stadium).

While not a Baltimore Ravens fan (remember that awful playoff game in January 2013?), they are to be applauded for replacing their synthetic field with real grass this year. The Ravens players lobbied ownership to make the change to grass. “To a man, players said they would rather play on natural grass than artificial turf,” says Don Follett, M&T Bank Stadium’s senior director of fields and rounds. “That’s consistent with NFL surveys showing that 90 to 95 percent of the league’s players prefer real grass. They say it feels better under their feet and provides a softer landing when they get knocked down. If your players feel better, they’re more likely to play better for you, and that carries a lot of weight.”

Rendering of new CSU practice fields (Source: CSU Source; Colorado State
Finally, another article in the Coloradoan this week noted that construction on a new SYNTHETIC practice field adjacent to the new stadium will begin this Saturday. It is part of a larger project that will “… serve as a gateway to the stadium, with plantings to celebrate and demonstrate the university’s agricultural heritage”. Simple question: how does a carpet covered with smelly, ground-up rubber celebrate “agricultural heritage”? Just asking....

Contrary to many of my colleagues here at CSU and possibly many readers of this blog, I was (and still am) fully supportive of the new stadium. But that doesn’t mean I can’t ask the question: why install a playing surface that is proven to increase the potential for injury to student athletes when we have the opportunity and resources available to install real grass? After all, if the CU Buffaloes can maintain a real grass stadium (used for graduation, as a stage for the Boulder Bolder, and to host concerts and numerous other events), certainly Colorado’s Land-Grant university could do the same? Go Rams... but don’t let Cam do any grazing on your fields.
University of Colorado's beautiful grass Folsom Field
(Source:Kai Casey/CU Independent)

Tuesday, October 11, 2016

All America Enchanting Pumpkins

Posted by Carol O'Meara, Boulder County Extension

When I plant my garden each year, two things are guaranteed to happen: I arrogantly predict which crop is going to be a beauty that year, and Mother Nature responds by turning a different crop into the blockbuster.  We’ve never seen eye to eye so it came as no surprise to me that, this year, pumpkins ran amok in the garden.

So prolific and early were the pumpkins that I had fully ripe ones before harvesting a single cucumber from the patch.  The vines climbed up and over beds, roses, and sunflowers to reach the front yard.  Friends touring the garden often started counting all of the orange gourds, only to stop in exhaustion because of the sheer number of fruit before them.  Tall, flat, round, and itty-bitty, this is the year of the pumpkin for us.

I blame All America Selections for this.  Between their Cinderella’s Carriage, Sorcerer, Wee-B-Little, and Pepitas, there are pumpkins all over the place.  Each one has endearing attributes and, though all are orange, they serve very different purposes.
Cinderella's Carriage, Courtesy AAS
Cinderella’s Carriage:  AAS describes this as a fairy tale type pumpkin, but don’t worry – it doesn’t reach out and grab toddlers like one of the Grimm Brothers’ tales.  Cinderella’s Carriage is eager to grow and shakes off trouble from Powdery Mildew.  The flat, round fruits are bright red and bake up sweet and nutty, perfect for fall soups, stews, or side dishes.

Sorcerer, Courtesy AAS

 Sorcerer:  If you want a big, traditional Jack O’ Lantern, Sorcerer has all the right magic.  It has a deep orange color with light ribbing that give it a classic pumpkin look.  These were the ones rambling along the garden and spellbinding passersby; their size and gorgeous coloring had neighbors and friends commenting on them.

Wee-B-Little Courtesy AAS
Wee-B-Little: a round, adorable little pumpkin that is the perfect miniature of its larger cousins.  A 1999 introduction stays fairly compact for its ilk; only eight feet of shoulder room is needed for the vines.  The tiny, eight-ounce gourds tuck nicely into cornucopias, on desks, as centerpieces, or entry table d├ęcor.  As a bonus, they make an unforgettable side dish to meals when baked like winter squash.  The flavor is nutty, slightly sweet.  Leave them whole for culinary drama, but pierce them before roasting whole. 

Pepitas, Courtesy AAS
Pepitas:  The real winner in this year’s pumpkin patch was this gorgeous little pumpkin.  With stripes and speckles of green against an orange background, this was the plant that produced and ripened fruit before the cucumbers even thought about flowering.  From a cook’s perspective, Pepitas has what its larger cousins don’t: naked seeds.  So if you love pumpkin seeds but not the dry hull, go naked with Pepitas. 
Help your pumpkin last with these tips:

-  Strong stems keep the pumpkin fresh, so look for those that are fully attached to the skin.
 -  Choose firm, not mushy pumpkins.  Avoid those with cuts in the skin; they’ll rot quickly.

 -  Keep your pumpkin cool, not freezing or overly hot.   Store away from direct sunlight, and bring it in if frost is predicted.

Once your pumpkin is picked and safely home, keep it fresh and ready for the big night with these tips:
- Wait to carve your pumpkin until one or two days before Halloween.

- Scrape out the walls to a thickness of one inch for easiest carving.
- Immediately after carving, smear petroleum jelly over the interior and cut surfaces to lock moisture in.

- Pumpkins wilt in three days; perk yours up by soaking it in water.  Mix one teaspoon of bleach to one gallon of water to prevent mold from growing.

Friday, October 7, 2016

Wear Rose Colored Glasses in Aftermath of Freeze

Posted by Mary Small, State Master Gardener program coordinator

We all know that sometimes Nature can be downright cruel in the garden. Like most gardeners, I don’t like early freezes in the fall and late ones in the spring. I immensely dislike psyllid infestations on my tomatoes. But sometimes the perceived “cruelty” or “problem” can also be beautiful. So put on some rose-colored glasses for the next few moments.

Webbing reflected in light
Yesterday there was rain, hail and then finally a freeze last night in Fort Collins. (I never understand how it can be cloudy all day long and then clear at night - something seems wrong with that picture, but I digress.)  It was obvious this morning that some annuals had bitten the dust. So I went out to take pictures of the damage  for use in my classes and while doing that, discovered beauty.
Look at the intricate webbing  within these impatiens! I would have missed it if the plants weren’t damaged by the cold and still covering it up.

While unsuccessfully taking a picture of ladybug pupae on this tomato (see background) I found these water droplets being held aloft by the trichomes.  

Trichomes on tomato
There were also a lot of water droplets on this geranium.

What do you think about these two “new” varieties of zinnia? I’m not sure why the damage(browning) appears in this pattern, although I suspect it has to do with petal maturity and the accompanying ability to withstand different levels of cold. 
Next time there's a freeze in your area, take a few minutes to breathe deeply, assess the damage and look around with a pair of rose-colored glasses. I think you'll be amazed what awaits you!

Thursday, October 6, 2016

Design a Native Plant Garden - upcoming webinar

Have you ever wanted to design a native plant garden or expand an existing one?  You won’t want to miss this class - Webinar – Designing a Native Plant Garden, scheduled for Thursday, November 3 from noon to 1 p.m. From the comfort of your home or office, you’ll learn how to design and develop your very own native plant garden. 

This webinar is a fundraiser for the statewide Native Plant Master Program, with all proceeds going to benefit the program, so please consider registering to support this CSU Extension program. Meet the presenter here. Register at

This online class will be taught by Deryn Davidson, Horticulture Agent with CSU Extension in Boulder County. Deryn was formerly a horticulturist at the Ladybird Johnson Wildflower Center. Register at For more information, contact or call 303-271-6621.