CO-Horts Blog

Tuesday, May 29, 2018

Crabgrass is Here - Finally!

Tony Koski, Extension Turf Specialist

Seedling crabgrass (May 22) in Fort Collins.
Notice the young plants are coming up in a dead
plant (a weed "cadaver") from last year. This is
why it's important to encourage healthy grass
growth in weedy lawns in the fall - to break the
cycle of seed germination the following year.
The up and down spring – periods of above normal heat and below normal cold spells – has delayed crabgrass seed germination by about 2 weeks. That’s a good thing if you were a little late putting out your crabgrass pre-emergence herbicide (aka crabgrass preventer).

But now that crabgrass HAS germinated, control efforts (if you want to control crabgrass and its warm-season weedy cousins – foxtail and barnyardgrass) should be focused on post-emergence herbicide products. Once you can see these annual grassy weed seedlings, it is too late to use a pre-emergence product.

As with any landscape pest, it is absolutely essential that you accurately identify the pest in question before purchasing and applying the control product. It makes no sense – environmentally, financially, and for your precious time – to apply a product that won’t work because you haven’t correctly identified the pest.

This is not crabgrass! Crabgrass and other seedling
grassy weeds are still very small now. This is a
clump of tall fescue - which will not be killed by
crabgrass control products containing quinclorac.
For example, crabgrass and the other just-germinating warm season grassy weeds are still very tiny now. If you have large, fast-growing, “ugly” (coarse, clumpy, wide-bladed) grass growing in your lawn NOW it is NOT crabgrass – which means that none of the herbicides labeled for control of crabgrass will eliminate these unsightly, undesirable grasses. We have blogged previously about grasses that people mistakenly refer to as “crabgrass”. These unattractive, perennial grasses can’t be controlled with either the pre- or post-emergence crabgrass control products.

What to use NOW for young/seedling crabgrass, foxtail, and barnyardgrass? The following products are available in the garden product aisle at big-box and hardware stores, and at better nurseries and garden centers. What they all have in common is the ingredient “quinclorac” (and all contain herbicides for broadleaf weed control as well, like 2,4-D, dicamba, MCPP, etc.). Quinclorac provides excellent control of the most common summer annual grassy weeds: crabgrass, foxtail, and barnyardgrass in bluegrass, ryegrass, and fescue lawns.

Bayer Advanced Lawn Weed & Crabgrass Killer (quinclorac, 2,4-D, dicamba)
Ferti-Lome Weed Out with Crabgrass Killer (quinclorac, 2,4-D, dicamba)
Monterey Crab-E-Rad Plus (quinclorac, 2,4-D, dicamba)
Ortho Weed B Gon Max plus Crabgrass Control (quinclorac, 2,4-D, dicamba)
Roundup for Lawns - Northern Lawns (make sure it’s the Roundup FOR LAWNS!; quinclorac, dicamba, MCPA, sulfentrazone)
Spectracide Weed Stop For Lawns Plus Crabgrass Killer (
quinclorac, dicamba, 2,4-D, sulfentrazone)

Crabgrass and its cousins are much easier to
control now - when they are small plants- than
in a couple of months when they have grown to a
plant of this size. Large crabgrass plants are very
difficult to kill.
It’s much easier to control crabgrass and its cousins this time of the year, when they are small. These grasses grow larger very quickly as we get sustained warm/hot temperatures. Large crabgrass plants are much more difficult to kill.

Make sure that you are spraying the right product for the weed in question! If you need help with the identification of weedy grasses – or any weed – in your lawn, you can bring a sample to your county Extension office. Or email me a high resolution photo of the grass ( 

We've blogged about crabgrass and other weedy grasses before...go here and here to see more photos of crabgrass and other weedy grasses, with hints on how to identify and control them.

And, as always, read the label for any pesticide you use and follow all instructions to ensure effective weed control and to avoid injury to your lawn or other non-target plants in your landscape.

Thursday, May 24, 2018

Springtime means mowing...and mowing again

Posted by: Alison O'Connor, Larimer County Extension

When it comes to the lawn, I'm a total Lawn Geek. I love my lawn. I'm pretty sure it stems from my days mowing lawns when I was a kid. My brother, Jeffrey, had a business called the "Lawn Ranger" and he gave me a few select clients (read: clients he felt weren't as lucrative to him). I love the smell of fresh cut grass and my sneakers stained green from all that chlorophyll. Maple the beagle also enjoys her green feet.
Maple pretending to be disinterested...but she's really proud of her green paws!
But this time of year, it's tough to keep up with the lawn and how quickly it's growing. Cool season grasses, like Kentucky bluegrass and tall fescue, seem to grow inches overnight and mowing the lawn to keep it tidy can seem like a chore. Plus, you're trying to time mowing between rain showers. Recently, it seems I've rushed home from work to mow, only to find that the lawn is too wet from a shower that blew through. Drat.

At each mowing, obey the 1/3 Rule. This means you don't remove more than 1/3 of the total leaf tissue. This helps keep the lawn neat and prevents hay piles. What this also means is you may have to mow two or three times each week in the spring since the grass is growing so fast. (For someone like me, it's great! For others, this is where mowing becomes a pain.)  NOTE: Those who do mowing for a living - commercial mowing and landscape firms, parks, etc. - mow on a schedule and sometimes can't stick to the 1/3 Rule. This is real life. Fortunately, the grass survives!
A comparison of mowing heights. The photo on the left is how tall the lawn was prior to mowing. The middle picture is ignoring the 1/3 Rule and cutting it too short. The photo on the right is mowed at the proper height for the height of the lawn.
Hay piles are ugly, often clump together and can discolor the grass. Worse, hay piles means you've removed too much plant tissue, which can stress your turf. Stressed turf is more susceptible to drought, weed pressure and disease.
(Not my yard!) Hay piles. We've all done it, but try to avoid this by obeying the 1/3 Rule.
Worse than hay piles are scalping the turf. This means you're essentially removing ALL of the leaf tissue. Doing this in the spring, even once, can result in the turf struggling all season. Don't scalp. Raise your mowing height!
I couldn't bring myself to fully scalp the lawn, but you get the idea. This is just a bit too short and the lawn will get stressed.
Over the weekend, I cut the lawn with the mower set at its highest height. The lawnmower was still sputtering and choking (so was I, for that matter). Once you get the lawn height under control, mow regularly to keep it at that height (still obeying the 1/3 Rule). Once the spring growth rush has passed, set your mower at one height all year and keep the grass at 2.5 to 3.5" tall, depending on what you prefer.
Ahhhh....fresh cut grass!
Mulch your grass clippings back into the turf. Mulching keeps fertilizer (and pesticides) in the lawn system and provides free nutrients! Grass clippings are mostly water and do not add to thatch problems. I only bag my clippings a couple times of year--when the grass gets too tall and mowing nearly kills the engine and also when I want to use clippings in the garden (or feed them to the chickens).
The garlic is lovin' the grass clippings!
Lizzy is a Lawn Geek too!
So there you have it. Maple was a good citizen and helped me mow the lawn and kept track of the height. I mowed once on Sunday and again on Monday, just to reduce the height and get the lawn a bit more tidy. You can see my progression below.
It's good to use a beagle as your measuring device for your lawn. At least the lawn isn't up to her knees anymore!

Wednesday, May 23, 2018

2018 CSU Cool Season Trial Results

Posted by James E. Klett, Professor, CSU Department of Horticulture and L.A.

The 2017-18 Cool Season Trial evaluated 121 varieties planted in mid-October 2017 through April 2018. Numerous varieties were selected as top performers by Flower Trial Garden Committee on April 25, 2018.

During the trial, all plants were monitored and observed weekly. They were watered and liquid feed until sprinklers were winterized in early November, then hand watered when soil was dry and temperature above 40ºF. There was some snow cover for about 6 to 8 weeks during the trial period. The top seven are described below. These cool season plants should be considered when planning your fall/spring color displays. They will brighten up your fall into winter displays and winter into spring displays. For more information visit our website, and click on cool season trials.

·         Best of Show Pansy- ‘FreefallXL Purple Face’ from Floranova

Plants were vigorous and sturdy as well as being covered by blooms. White centers really made the dark purple stands out. Vibrant flowers covered the plant all over including not just the top but also sides of plant. This entry also won the Best Trialing Pansy category.

·         Best Light Blue Pansy- Pansy Inspire® Plus Exp. Marina Improved from Benary 

Plants were very uniform and blooms covered the top as well as on the sides. The light blue color was around the outer edge of the flower followed by a band of white and a dark purple/blue center created a great combination of colors. A dainty appearance is created by the unique flower color combined with slightly ruffled petal edge.

·         Best White Pansy- Cats™ White from Benary 

Plants were noted for impressive flower power and a nice uniform growth habit. Attractive purple whiskers added interest to the slightly primrose colored flowers with a splash of yellow in the center. The color of this pansy would brighten up any landscape border or container planting.

·         Best Yellow Pansy- Spring Matrix™ Yellow Improved from Pan American Seed 

The bright yellow flowers were very abundant and eye catching as they were well above the foliage for maximum flower power. Clear yellow flowers had no markings so color really popped.  The abundant blooms were also noted for being weather resistant and maintained their shape.

·         Best of Show Viola- Viola Endurio® Blue Yellow with Purple Wing from Syngenta 

Plants were highly rated for great vigor and uniformity. Vibrant flowers were a combination of three different colors. Varying shades of dark purple, violet and yellow created a lot of interest and although flower color was variable the overall result was very captivating. A spreading habit makes it best massed in beds or dripping out of a container. This entry also won the Best Novelty Viola category.

·         Best Light Blue Viola- Bel Viso Marina Improved from Floranova   

Plants had a very nice mounding growth habit. The flowers were very abundant on uniform plants. The light blue flower with white centers had a smaller dark blotch for a unique eye. Its tidy and uniform growth habit makes it great for tight spaces, narrow boarders and window boxes or tucked into a rock garden. 

·          Best Yellow Viola- Bel Viso Yellow from Floranova
The vibrant blooms were a unique shade of yellow and had small dark whiskers. Flowers seemed to be slightly larger than others in this category.  The vigorous plants looked like a bouquet of prolific yellow flowers.  

Tuesday, May 22, 2018

Gardening for Drought Conditions

Here in Western Colorado we only got ½ of our average moisture last year and we are not doing any better this year.  Although the North and East portion of the state has gotten more moisture, since waters from Western Colorado are piped over the divide to Eastern Colorado, we all win if we can use our water sparingly.


Drought Intensities

·               None: No Drought
·               D0: Abnormally Dry
·               D1: Moderate Drought
·               D2: Severe Drought
·               D3: Extreme Drought
·               D4: Exceptional Drought

Concerns with drought are saving trees since they are much more permanent and provide so many benefits from shade to reduction of crime and about 100 more reasons to have trees.  Water for the trees.

 Often we see people retrofit their landscape to xeriscape (dry scape or low water landscapes)but they forget about the needs of the trees

Xeriscape does NOT have to mean cactus and succulents, but we love ours at the TRA Mesa County Extension Office, Photo by Susan L. Carter

And certainly there are certain situations where we need grass like ballfields areas for pets etc…  But we can minimize the amount of lawn and water features that are not necessary.
If starting a new landscape, use the principals of xeriscape.

Note I did not say ZERO scape, there is no such thing and rockscapes are very hot and increase cooling needs of your home and business thus using more water. Use plants that require less water like native plants suited to your elevation and area are great choices.
Studying Plants on the Grand Mesa, Photo By Susan L. Carter
And consider that sometimes we have areas that are naturally wetter such as drainages or seeps, so install plants that like more moisture in those situations.  We call that Right Plant, Right Place. 
Here is a recent video I did for our area on ideas to save water. Water Landscape Drought Go to the Pro Tip:

And some quick bullet points of what is in the video as well as additional tips.
  •  Turn off your sprinklers before there is runoff.  Runoff lets us know the soil is a “field Capacity”, can hold no more water, and may deprive the roots of oxygen thus suffocating your plants.
  • Make sure you are not irrigating hardscapes such as patios, driveways and sidewalks.
  • Use a long skinny screwdriver or soil moisture to check moisture at 6” or deeper depth to determine if you need to water.
  • Water at night.  And don’t set it and forget it; I’m talking about your irrigation clock.  Watering needs peak in July.  Then start to reduce irrigation to slow plants down for fall.  They will acclimate better to winter and be healthier.
  • Never water everyday unless you just installed seed or sod.  Then water daily for the first month and start switching to less frequent deeper soaks to get roots deeper.  If you have to water daily to keep plants alive then something else is wrong like improper irrigation system setup or soil issues.  See our LISA, Landscape Irrigation Self Audit Website, and ask your local Agent if they have a kit you can check out.
  • Turf will get a blue tinge or footprints will stay in the lawn when it needs water.
  • Group plants with similar watering needs together.  This is called Hydrozoning.
  • Watering During Drought Factsheet:

You can create beautiful landscapes using low water plants it your choices are much larger than just cactus, although they can be beautiful too. 

Yellowhorn Tree and other Xeric Plants at Mesa County CSUE TRA office
And remember when first planting, even a cactus needs water to get established.  So be a savvy water-er and check your plants and soil before you water and we will all benefit.  Enjoy where we live, it’s a drier state. 

By Susan Carter, Horticulture Agent, CSUE Tri River Area.

Thursday, May 17, 2018

Tree Planting No-No's!

Posted by:  Amy Lentz, Weld County Extension

It’s planting season all across Colorado, from agricultural crops to flowers to trees. It’s the latter that I want to address today in this blog…planting trees! Our towns and cities are growing (fast!) and with this comes the planting of a LOT of new trees, both in public spaces and on private property. Planting trees in the correct manner is the most beneficial thing you can do for a tree’s health as it will be the foundation of the tree for the rest of its life. If these newly planted trees start off at a disadvantage, it could invite many insect, disease and other tree health issues down the road. And let’s be real, trees are not cheap! They are quite an investment that will eventually pay off down the road once the tree matures…if it’s been properly planted and cared for as it gets established.

Being a tree in Colorado isn’t all that easy with our dry climate, wide swings in temperature and less than ideal soils in most locations (among other hurdles). This makes it ultra-important to help these newly planted trees get off to a good start in life. If planted incorrectly, these trees can be doomed with a death sentence from the day they go in the ground, but you won’t see it right away. In many cases, a poorly planted tree will not show symptoms of poor planting until a few years later.

Here’s my list of 5 Tree Planting No-No’s:


You should plant the tree so the root flare (where the tree’s trunk meets the top of the roots or the top of the root ball) sits just slightly above the existing soil level, 1 to 2 inches. Measure the root ball before you start digging and check the depth periodically as you go down. You can always remove more soil if the hole is too shallow, but soil that has been added back into the planting hole will not act the same as if it were not disturbed. Instead, it will settle and the tree will likely sink causing it to be planted too deep.


The hole should be 3 times the width of the root ball of the tree and have sloping sides. This is especially true for trees grown in containers, as their roots need to adjust from growing in a barky potting mix to growing in heavy soils. Digging the hole wider will loosen the soil so the roots can grow and adjust more easily to the native soil.


This tree was easily pulled from the ground years after it was planted. It had a very poor root system due to the wire basket being left in place at planting. A Big No-No!

I can’t stress this enough. I have seen trees succumb to a slow and horrifying death because wire baskets have been left in place. Not only is the tree you've invested in dead after a few years, you have also lost years of growth and will have to start over. Burlap and rope should also be removed as these will not break down fast enough in our Colorado soils, hindering the root growth of the tree and causing the same demise. So take the time to remove the basket and place the tree gently into the planting hole. This is also a good time to check for circling roots or roots growing across the base of the trunk and direct them away from the base of the tree.


Just say no!

I have seen a lot of this lately! Trees take up water and nutrients from their roots, not their trunks. Therefore, the trunk does not need mulch to help conserve water or protect the tree. Instead, it hurts the tree. Having mulch piled up around the base of a tree can lead to the wood rotting and inviting pests and disease to attack the base of the tree. Don't get me wrong...mulch is a great thing! I love seeing trees with good-sized mulch rings underneath as this creates a favorable environment for the tree’s roots and keeps mowers and string trimmers away from the tree. So use mulch, just use it in a 2-3 inch layer out to the drip line for a new tree, keeping it a few inches away from the base of the trunk.


Too tight.
Just right.

A newly planted tree needs encouragement to grow strong roots. Think of it like an arm in a cast…without the ability or need to move the muscles, they become weak. If we baby a newly planted tree too much by tightening the staking straps to the point of no movement, the tree will not form as strong of a root system because it doesn’t have to in order to remain upright. Staking straps should have a little wiggle room so the tree can still sway in the wind. Furthermore, if they are too tight, they could girdle the tree’s trunk as it grows in size. Straps should only be left on for the first year a tree is in the ground.

There are many other helpful recommendations when it comes to planting trees. For the complete story, check out the following resources from CSU:

Tree Planting Steps - Colorado Master Gardener Garden Note #636

The Science of Planting Trees - Colorado Master Gardener Garden Note #633

Tuesday, May 15, 2018

Iris Season

Iris Season
By CSU Horticulture Program Associate, Linda Langelo
This is my favorite flower, among other favorites.  Of all the unique, unusual flowers iris stand above the rest with their bold, showy petals.  Of course, there is no bias here.  Irises can create a mass of color that is striking, but don't blink.  That color disappears quickly.  However, they are memorable. 
The best part is that they come in all colors.  No matter what the color palette of your landscape there is always room for an iris to match or compliment.  From white to every color of the rainbow and then dark, rich colors such as purple and black.
Iris are easy maintenance.  Their rhizomes love to bake in the heat of the summer.  After the first frost in the fall, their leaves need to be cut back.  In late spring or early summer after they bloom, if they have lost their vitality or are not as prolific, it is time to divide the iris.  Dig up the rhizomes using a digging fork, anytime from July through September.  The heat and dry soil in summer is perfect for discouraging soft rot on the rhizomes.  Separate the old clumps of rhizomes by using a sharp knife.  Dip the knife in 10 percent bleach solution between dividing clumps.  It is best to save the strong outside pieces of a clump.  Cut the rhizomes into pieces with each having a single fan of leaves.
Photo Credit:  Gardenia-Creating Gardens- Iris 'Beverly Sills'

Also cut the leaves down to a third of the original length.  Then plant the divisions with the rhizomes barely covered.  Plant them so that the fans are facing in one direction.  For those of you who are visual learners here is a short series of instructions, illustrated through photos.

Here is a picture step-by-step instructions for dividing iris from University of Maryland Extension:

Photo Credit: University Of Maryland Extension

Step 1: Dig irises by using a spading fork.

Photo Credit: University Of Maryland Extension

Step 2: Remove the soil and check for root rot or borers.

Photo Credit: University Of Maryland Extension

Step 3: Discard old or rotten rhizomes.  Cut the rhizomes to a few inches(as you will see in the next slide.)

Photo Credit: University Of Maryland Extension

Step 4:  Let the newly cut rhizomes stay in the sun for a day or two.  During this a suberization process occurs meaning - to make impermeable by the formation of suberin in the cell walls, changing them into cork.  The cells suberize.

Below is an iris now blooming at my house:

Photo Credit: Linda Langelo

I moved into a new home last year and a friend had asked if I wanted some iris.  I had flower beds but they were completely empty.  He said that they were yellow and that is all that he knew about them.  A mystery iris.  These iris flower early and are shorter than most.  They are perfect for the backdrop of the foundation which is painted green.  I think I have them properly identified as Scholar.  Scholar gets to be 13 inches and is a standard dwarf bearded iris.  It was developed in 2000 and does not rebloom later in the season.  It flowers early meaning early May to mid-May and will continue for another week depending on the weather.  I identified my mystery iris.  Do you have a mystery iris in your garden?

Thursday, May 10, 2018

What’s That Bug (Egg): Mantids and Katydids

Posted by Jessica Wong, Master Gardener Coordinator, Broomfield County Extension 

Winter can be a dull time for an entomologist. Like many plants, some insects go dormant for the winter. But now it is spring and the insects have resumed activity and so have the entomologists. 

Something that looked and felt a bit like a packing peanut glued to the branch of magnolia was brought in to the office a few weeks ago. This “packing peanut” is actually an egg case of a European mantid, Mantis religiosa. European mantids are non-native to Colorado, but they are well established here. In fall they lay multiple eggs (sometimes hundreds!) covered with a dried insulating foam on pretty much any solid surface. The eggs survive through the winter and start hatching in late spring. With this heat wave, some baby mantids might already be out. They look like the adults, but smaller. 

European mantid egg case on magnola. Photo by Jessica Wong
Gardeners like mantids because they are predators that feed on various insects, including some pests. However, mantids can be picky eaters and may not provide effective pest control. They mostly feed on gnats, flies and bees. A young mantid may cannibalize others as they emerge from the same egg case, and an adult female typically only eats the male during mating if she is starved.

Female European mantid laying eggs. Photo from by Lynette Elliot
More recently, a butterfly bush twig with two meticulous rows of eggs came in to the office. These are the eggs of a broad-winged katydid, Microcentrum rhombifolium. Their eggs can be found in double rows on twigs or in single rows on leaf margins. Similar to mantids, these katydids lay eggs in the fall that hatch in the spring. Katydids are herbivorous and will feed on the leaves of shade trees and other ornamental plants. However, they do not occur in high concentrations and typically do not cause harm to plants.

Double row of broad-winged katydid eggs on butterfly bush. Photo by Jessica Wong

Broad-winged katydids are seldom seen, but are often heard at night in the summers in Colorado. The males make loud “lisp” and “tick” sounds, and females respond with less audible clicking. Katydids produce sounds by rubbing the bases of their wings together - a process known as stridulation. On the base of one forewing is a set of tiny pegs called a file, and on the other forewing is a ridge called a scraper. The wings also have a smooth membrane that amplifies the sounds made from rubbing the file and scraper together.

Spring has just begun, but these insects have me dreaming of summer already.

Broad-winged katydid male. Photo from Colorado State University "Colorado Insect of Interest"