CO-Horts Blog

Thursday, May 30, 2013

Battling Jacques the Rabbit

Posted by: Mary Small and Curtis Utley, CSU/Jefferson County Extension

Rabbit clipped peppers
One of the sure signs that life has returned to our demonstration and research garden here on the Jefferson County fairgrounds is that the resident cottontail rabbit, Jacques, has been busy.
He’s found a good life here with refuge underneath a couple of large shrubs abutting our building and plenty of gourmet food to eat once it gets planted by his humans. No more of that yucky grass and those weird-tasting perennials from the High and Dry garden.  It’s time for the tender lettuce, spinach and other yummy greens.
We thought we foiled Jacques last year by placing the greens in a 3 foot high raised bed, rather than the in-ground bed where they were the previous year.  Voila-it worked! (Against Jack, anyway, not against pests of the human and insect varieties.)
This year Jacques has been getting even by clipping off many residents of our just-planted pepper research bed (at a nice 45 degree angle, as they so artistically do!)  And to add insult to injury, he’s just clipping some of them off and dropping the tops nearby as if to taunt us.  He’s not eating everything, just getting his revenge.

Rabbit proof fence
Two foot wide one-inch poultry netting
stapled to two foot survey stakes

It’s a bit hard to get a harvest and compare performance of pepper varieties when some of them are damaged right at the beginning of their garden life. Thanks a lot, buddy!
So, what to do?  Two foot tall stakes were hammered into each corner of the bed and along the sides. Next, two foot wide chicken wire was tightly wrapped around the stakes. As you see in the photos the fencing is tight to the ground and encloses the perimeter. We hope it will be tough for Jacques to dig under so he will give up and find something else to do.
The fence will make taking data later in the summer a bit more challenging, but at least we should have something to measure!  We’ll see just how clever this guy is as the season progresses and what he decides to do in the meantime.

Wednesday, May 29, 2013

CSU Flower Trials: "Best Of" Annuals from 2012

Posted by: James E. Klett, Professor & Extension Landscape Horticulturist

Annual Flower planting time is upon us and you should include some of CSU’s Best Of’s from 2012 in your flower garden this year. These plants have proven to be exceptional from our trials and are quite adaptable to our Colorado climate.

The garden (1401 Remington Street), which spans about three acres on the east side of the Fort Collins campus near the University Center for the Arts, is a northern Colorado showpiece with a focused research purpose. The Annual Flower Trial Garden tests and analyzes the performance of more than 1,000 varieties of annual bedding plants in Colorado’s harsh growing conditions.

Three plants that you will definitely want to trial and plant in your garden or in pots on your deck or patio for 2013 should include some of these top performers:

Our Best of Show from 2012 was Dahlia ‘XXL Hidalgo’ from Dummen USA. This plant brings a unique class to the garden dahlia category and was a standout without special care. Flowers are relatively large and have a deep, rich “butter-French” color. Flowering started early in the season and continued strong late into the early fall. The flowers are complimented by dark green foliage. It also makes a good cut flower and adds stature and glamour to any garden.

"Butter-French flowers" of XXL Hidalgo dahlia
Our Best New Variety from our 2012 trials was Lantana ‘Luscious Berry Blend’ from Proven Winners. It is definitely an eye-catcher due to beautiful blend of bright flower color. Plants have great vigor and form a dense canopy and are quite drought adaptable. This plant produces virtually no fruit or seeds and saves its energy for a consistent show of blooms. Great plant for that sunny, hot location in your garden.

Luscious Berry Blend lantana 
Luscious Berry Blend planted in the ground
Our Best Novelty Plant has a real tropical look to both the flowers and foliage. Tecoma ‘Bells of Fire’ from Plug Connection was given this honor. Flowering begins early and continues through the summer. The flowers resemble those on a trumpet vine. Flowers are an attractive blend of orange/red and showy. This plant will give your containers a real tropical look.

The tropical flowers of Bells of Fire Tecoma

A complete listing of all our winners can be found on the CSU Annual Flower Trials website.
These plants should be available in most independent garden centers throughout Colorado. 

Tuesday, May 28, 2013

Free Xeriscape Garden Tour in Pueblo

Posted by Linda McMulkin, CSU Extension-Pueblo County

Please join gardeners in Pueblo for the 2013 Xeriscape Garden Tour on Saturday, June 1, and Sunday, June 2.  This free garden tour features public and private gardens that exhibit the principles of water-wise gardening. 
My husband and I attend the tour each year and get ideas for our own yard. Each garden is unique and reflects the interests and vision of the homeowner.  While I don’t want to bring all of the ideas into my yard, it is always fun to see how each homeowner interprets the principles of xeriscaping.  Be sure to bring your camera so you can record plant combinations or hardscapes that catch your eye.

 The Xerisicape Tour is a true community effort, with financial backing from local water districts, the Southeastern Colorado Water Conservancy District, the Pueblo West Community Xeriscape Gardeners, and Colorado State University Extension-Pueblo County.  Local green industry partners provide gift certificates for the homeowners who open their gardens for the tour.  Homeowners and volunteers from the Pueblo West Gardeners and CSU Extension will be on hand to answer questions.  

On Saturday, four gardens in Pueblo will be open from 9 am to 3 pm.  Pueblo West will be featured on Sunday, with five gardens open to the public, also from 9 to 3.  While you are in Pueblo, plan to visit the demonstration gardens located throughout the county as well as the streetscapes projects downtown and the gardens at the Pueblo Zoo, the Historic Arkansas River Walk (HARP), and the Rawlings Library. 
To download the tour maps, go to Colorado State University-Pueblo County Horticulture.
The photos were taken on previous tours.  Photo credits: Liz Catt, Orla O'Callaghan, Linda McMulkin, Warren Nolan.

Friday, May 24, 2013

New Research in New Windsor: A Turf-Tree Fertility Study

Posted by: Alison O'Connor, Horticulture Agent in Larimer County

I'm a sucker for punishment (but I like to say I have a "curious mind.").  I started another research project.  This time with the help of a few dozen Autumn Blaze maples in Windsor and Tony Koski.  There's a general consensus that when you fertilize your turf in a landscape, you're also fertilizing the trees.  Tree roots tend to be shallow (no more than 12" deep in most of our clay soils, but 6" deep in many situations) and need oxygen, so they are mixed right in with our Kentucky bluegrass roots.  Through an extensive literature review (I love the CSU Library), we found that very few replicated studies exist to look at how much fertilizer the trees are using compared to the turf.  Primarily because tree roots are rarely contained and the extent of tree root systems are unknown.

Enter the Autumn Blaze maples in the New Windsor Metro District.  I think they designed this place for us.  Ok, maybe not.  New Windsor is located just north of Windsor and it has these "beds" (medians) planted with a monoculture of bluegrass and Autumn Blaze maples (all the same age).  We are treating each bed as its own replication, which means that the roots for both the bluegrass and the maples are totally contained....and ours to study.  And there are enough beds to keep me busy for quite awhile.

Autumn Blaze maples as far as the eye can see
So what we're doing is pretty simple.  We're fertilizing each bed at one of two rates: 1 lb N/1000 ft sq or 4 lbs N/1000 ft sq.  Then each week, we're going to collect lawn clippings and analyze them for total nitrogen content.  Every other week, we'll pick a few leaves off a select number of trees and analyze them for total nitrogen and chlorophyll content.  What we hope to conclude is whether or not turfgrass fertilization supplies adequate nitrogen for trees growing in a bluegrass lawn.  We're looking at tree growth increments, leaf nitrogen and chlorophyll content and caliper.

Collecting turf clippings using a very sophisticated system
of a lawnmower and paint strainer bags
It's not that I don't support fertilization of trees...all I want to know is when you fertilize a mixed species landscape, do the trees receive adequate nitrogen to maintain growth...or is additional fertilizer necessary?  Or does the turf use most of the nitrogen?  It could change how we approach landscape fertility in the future. If we see no differences in tree response between the 1 and 4 pound nitrogen rates, then we'll know that most nitrogen is being used by the turf.  But if we see quantitative differences in terms of total nitrogen content and tree growth response, then we may conclude that supplemental tree fertilization is necessary.

So, what do y'all think?

Monday, May 20, 2013

Garden Companions

Posted by: Micaela Truslove, Broomfield County Extension

The practice of companion planting – interplanting crops that are mutually beneficial to increase the quality and yield of nearby plants – has been practiced for centuries.  Who doesn't remember their grandparents planting marigolds in the vegetable garden to ward off insect pests?  Many people have planted a Three Sisters garden at some point, which utilizes corn as a trellis for beans, beans as a nitrogen fixer for squash and nitrogen-sucking corn, and squash’s large leaves to shade out weeds. Though companion planting has long been a popular practice in the garden, there is little scientific evidence to support many of these plant associations.  However, there are many beneficial ways that plants can be used to help each other out in the garden.

Zinnias attract pollinators, so are a great
companion plant for the garden. (Photo: 

Micaela Truslove)
One such method is intercropping.  Intercropping takes advantage of plants’ different growth rates, sizes and root depths, allowing you to plant more intensively and make the most out of the growing space.  For instance, a common practice is to plant an early crop of lettuce next to tomatoes.  Shallow rooted lettuce will shade out the weeds while deeper rooted tomatoes get started, and will be ready to harvest by the time the tomato vines get too big.  Intensive planting in general helps to shade out weeds, but caution must be taken not to place plants too close together as this can encourage disease.

Somewhat related to intercropping is succession planting.  Planting short season crops ahead of longer season crops in the same place, though not necessarily at the same time, will allow for an early harvest of spring planted vegetables before longer season vegetables are planted out.  Good examples of this are spinach, radishes and peas, which can all be planted in the “shoulders” of the season (early spring and late summer).  These can be succession planted before and after main season crops, such as peppers and tomatoes.  Variety selection is important in succession planting.  Choose varieties that mature quickly to make sure there is enough time to plant all of your successions.  Another way to use succession planting is to plant crops in two or three week intervals to have a continuous harvest and to avoid a glut of any one vegetable (one can only eat or give away so many zucchini).

Trap cropping is also a useful tool in times of heavy insect infestations.  For instance, in a year when flea beetles are bad, planting a sacrificial row of radishes a little way away from your other brassicas, such as broccoli, will lure flea beetles away.  Eric Hammond, the Horticulture Agent for Adams County, noticed that flea beetles really loved his Basket of Gold (Aurinia saxatilis), so this might make a good trap crop for brassicas.  When you notice that certain plants make good companions, write it down so you’ll remember for next year.

Yarrow (Achillea millefolium) is a great example of a flower with
shallow nectaries and small flowers which can be used in the garden
to attract beneficial insects (courtesy of Carol O'Meara, Boulder County
Perhaps the most important way you can help your garden is to increase crop biodiversity and use plants that provide a habitat for beneficial organisms in the garden.  Many people don’t want to give up valuable vegetable real estate to plant flowers, but the benefits of doing so far outweigh the space you have to sacrifice.  Mixing plants of different colors, scents and ripening times and avoiding large areas of plants from the same plant family may confuse pests that are looking for a tasty meal. Herbs often have a strong aroma which may confuse insect pests, and they are also beautiful and useful for cooking.

In addition, plants with small flowers and shallow nectaries (think of your dill or fennel after they flower) often attract predators that eat other insects, including lacewings, lady beetles, assassin bugs, tiny beneficial wasps and syrphid (hover) flies.  Letting some of your vegetable plants flower will give you food and the benefit of flowers that attract helpful insects.  Learning what these insects look like through their various life stages will ensure that you are squashing the correct critters and leaving those that serve a beneficial purpose.  Pollinators are also very important as they are the reason many of our vegetables produce fruit.  Planting flowers that attract both honeybees and other bees is a great way to ensure good pollination.

Lady beetles, especially in the larval stage, are
predators of many insect pests. (Photo: Micaela

There are also negative plant associations.  The one to avoid in the vegetable garden is planting crops from the same family in the same location year after year.  Practicing crop rotation will ensure that your soil will remain healthy and disease free for the following planting season.  Plant crops from the same family in a different location every year. This is often very important for tomatoes as there are many soil-borne diseases that affect tomato plants.  If you are planting certain crops together to gain the benefit of the associations they form, just plant that entire block in another location the following year.

Though there is a lot of information out there about companion planting that has not been scientifically proven, there are many ways that you can use beneficial plant associations in the vegetable garden to create a healthier, more productive environment.  And there is no harm in testing out the more anecdotal associations.  Close observation and keeping good written records will help you identify what works best for you.

Thursday, May 16, 2013

The Weeds are Winning - Again...

Posted by: Susan Rose, Tri River Area Extension

Grand Junction – It seems to happen every year about this time.  The Master Gardeners and I always begin the season full of spring energy and hope – THIS year, we will get ahead of it!  And STAY ahead of it!

Rriiightt…It gets away from us so quickly our heads spin, and not in a good way.  The winter annuals have already set seed, so we’re scrambling to collect and bag them, knowing we’ll miss some and have another crop of cheatgrass, hare barley, blue mustard and flixweed next year.  The dandelions – well, you leave them for the bees one day (a pretty good excuse, I thought) and those puffy seeds are blowing all over the garden the next.  And the kochia – so cute and harmless last week – can it have bolted so fast?

I should perhaps mention that we have four acres of gardens on the Mesa County fairgrounds, that we are tasked with maintaining. For years it was nothing but weeds, so the seed bank is appalling. At the Master Gardener class a year ago, we were between county weed managers so I took on the weeds class myself.  I decided to show them what we were up against here, and identified 56 different species.  Welcome to my world!

Shouldn't this be our state grass?
Don’t get me started on the trees.  The street behind the grounds here is lined with Siberian elm, which apparently was considered a desirable tree here at one time – no Dutch elm disease!  The City of Grand Junction, back in the day when monocultures were considered elegant, planted my entire street in these nuisances.  I have five 80 year olds on the west side of my house, so I do believe it is in my best interests to maintain them, but that doesn’t keep me from swearing at the seedlings.  Here in our Arboretum, we often don’t see them until they peek up out of a rose bush – impossible to pull, but still too small to stump-treat effectively.  
They aren’t alone – we also have two types of mulberries and all the volunteer cottonwoods anyone could ever want.  Russian-olive and tamarisk keep showing up as well.

I confess to occasionally contributing to the problem.  A couple of years ago, a spectacular mullein showed up which grew to 15 feet with a beautifully fasciated crown.  I’ve been regretting ever since that I couldn’t resist the show.  We also have Tragopogon porrifolius, the pinky-purple version of western salsify – hey, it’s a pretty flower!  Hey, it’s everywhere!  I love interesting plants so I’ll probably continue to cause problems.

What's up with white top this year?
How do we set our priorities? Going after the things that are going to seed is number one, and after that, the noxious weeds especially if they’re being really invasive. Canada thistle, hoary cress (having a banner year here) and absinth wormwood top that list.  (I think we planted the wormwood; see previous paragraph.)  Anything that is strangling everything else – you can all guess what that is!  I have my personal priorities, too – Russian-olive gets zero tolerance, while another volunteer cottonwood might slide for a while.

After that, it’s all about looks.  The views from the parking lot and the paths get more attention than the back forty.  Weeds lower than a foot tall get less attention than the three and four foot ones.  And those pretty flowers may get a pass.

 Maybe, after all, we can stay ahead of it this year…

Monday, May 13, 2013

Ah, that crazy Colorado weather strikes again!

Posted by Andrea Cummins, Douglas County Extension

Once again, the schizophrenic Colorado climate has created havoc for many of our trees. As I see photo after photo (and lots of samples too) of evergreens that have “suddenly” turned brown, I think the finger of blame has to be pointed at Mother Nature. Although humans who fail to water regularly and effectively in the winter can share this blame.

Spruce showing varying amounts of drought and frost damage

With the past two years of drought, the scorching hot summer of 2012, and then the unusual cold temperatures of early April, the trees have taken a pretty big hit. Even with winter irrigation (we ALL water in the winter right?) evergreen trees are showing pretty serious winter desiccation symptoms. Add to this existing drought stress the extreme cold temperatures of early April (right when the trees were starting to de-harden from winter), and you have a perfect scenario for ugly, brown trees virtually overnight.

Young Ponderosa pine suffering from winter desiccation and cold damage

Winter desiccation occurs when there is low humidity, no snow cover, and windy weather. The plants loose more water through their needles then they are able to take up through their roots. When these dry conditions continue for years on end, as they have recently here along the Front Range, the trees become more and more stressed. The fine roots hairs (those that take up the water) can die in dry soils and this makes the problem worse. This is why winter watering is so critical – it cannot solve the problem of low ambient humidity and transpiration, but keeping soil moist at least gives the trees a fighting chance during those warm winter days. Desiccation tends to appear more frequently in exposed and windy sites, southern and western exposures, in years with little snow cover, and on younger plants. However, many of the photos we are seeing in the office are of mature trees – so they are not immune to this problem. Don’t think that you don’t need to water mature trees in the winter. Even though they have farther reaching root systems, they also have bigger canopies, and a lack of soil moisture will affect them as much as it does immature trees, sometimes it just takes longer for the symptoms to appear.

The cold temps of early April shocked the plants when they were starting to reawaken for spring. Trees “harden” their tissues for survival during cold temps and then “de-harden” for the growing season. When temperatures fluctuate to the extreme, as they did here in early April (and do frequently in our crazy climate) the trees cannot adjust quickly enough to protect their needles from the freeze. The buds are often more protected (as buds are the tree’s hope for the future), and the tree will send out new growth. We see this happening now with many of the deciduous plants that were just starting to leaf out and got nipped. The new leaves died but the buds were undamaged and are producing new growth. Hopefully this will happen for the evergreens as well. 
Austrian pine in front will likely recover, although it will lose the brown needles. The spruce behind may be a goner. Pine is toward the bottom of the hill and therefore gets more moisture as compared to the spruce at the top of the hill. 

So what to do now? Wait and see what happens. While the needles may have died due to the extreme cold, the buds themselves may still be healthy and able to push new growth. It is just too soon to tell. The ability of the tree to recover will be directly tied to how stressed it was going into the April freeze --again with the winter watering. Those trees that were already in extreme drought stress will be much less likely to have the energy reserves to recover. Put your pruners and loppers away for a few more weeks and wait and see what your trees do, with a bit of kindness from Mother Nature (think 70 degree weather for a while) and regular irrigation, they may snap back. 

Friday, May 10, 2013

Adding Pizazz to the Landscape

Posted by David Whiting, Extension Consumer Horticulture Specialist, Department of Horticulture & LA, Colorado State University.
During the next few weeks, gardeners will be busy adding annuals and new perennials to the landscape.  Let us review a few landscape design techniques to give pizazz to  the garden.

 In landscape design, use of color is not about mixing all the colors.  But rather about selecting colors to create moods and feelings that match the activities of the various outdoor rooms.  For example:
  • Red engenders passion, courage, power, wealth, motivation, and fame.  Some like the energy that red brings.
  • Yellow engenders joy, happiness, communication, inspiration, sunshine and optimism. 
  • Blue engenders imagination, calm, serenity, relaxation, compassion, and reflection.  It is almost magical in creating the feeling of peace and tranquility.
  • Green engenders harmony, beginnings, prosperity, nature, growth, and healing.  Green is amazing in its ability to help heal physical and emotional pain.
  • Orange engenders enthusiasm, joy, exuberance, interaction, fun, captivation, and sex.  Most people have a love or hate relationship with orange.
  • Purple engenders intuition, devotions, respect, peace, spirituality, and awareness.  In all cultures of humankind, it has been the color of deity and royalty.
  • White  In the landscape, white is a dominate color rather than neutral.  Thus, it is not the best team players when mixed with other colors.  For someone who enjoys being in the garden at night, consider a white garden, also known as a night garden.   In the moonlight, whites and silvers, and grays come alive, while other colors go to bed at sundown.
  • Pink engenders love, sweetness, uplifting, happiness, tenderness, and enticement.  This is one color where there is no agreement among people about the feelings and moods that it creates.  For most, pink is either a love or hate relationship.  Even different shade of pink may create different feeling and moods.

This paring of the round flower with the spike flower is popular at Butchart Gardens, BC, Canada.  For dominance and subordination, fill the bed with 1/3 of one flower and 2/3 of the other flower, not half and half of each.

Warm colors (reds, oranges, and yellows) are conspicuous, cheerful, stimulating, come forward and have high energy (scale).  Use warm color in outdoor rooms with action, parties, and entertainment. 

Warm colors work best when used in color sequence.  For example, in an orange / yellowish-orange / orangish-yellow / yellow sequence, the orange would dominant.  Use the orange at the focal point.  In sequencing to the yellowish-orange, add at least 1/3 more of the yellowish-orange plants.  Then, in sequencing to the orangish-yellow, add at least 1/3 more plant.  And, at least 1/3 more plants again as it sequences to the yellow.  This sequencing builds the landscape design principle of emphasis (dominance and subordination).  Note this is not ¼ of each color!

Here at Butchart Gardens, daisy flowers are paired with red leaf cannas.
Cool colors (blues, purples, and greens) are less conspicuous, restful, recede, suggest distance, and low energy (scale).  Use cool colors in outdoor rooms for relaxing, reading, and reflection. 

Cool colors sequence best in color contrasts.  For example 2/3s light blue and 1/3s dark blue, or 1/3s light blue and 2/3s dark blue.  This one-thirds/two-thirds sequencing builds emphasis (dominance and subordination).  Note that is not half of each.


Here the dainty flowers of yarrow are paired with the larger poppy.

Effective plant combination – To create effective plant combinations, always pair opposites.  For effective plant combinations, pair the fine with the coarse, the round with the upright, the short with the tall, the thugs with the dainty.  So as you buy a plant, consider who will be its opposite mate.


This technique is call color echoing.  The minor color in one flower is repeated as the major color in the other flower.  For dominance and subordination, fill the bed with 1/3 of one plant and 2/3 of the other plant,  not half and half of each plant.

For additional information, refer to Chapter 46, Principles of Landscape Design, in The Science of Gardening, or CMGGardenNotes #413.

Monday, May 6, 2013

Confused about rainwater collecting?

Posted by Irene Shonle, CSU Extension in Gilpin County

Ever wondered why there are so few rain barrels for sale in garden centers in Colorado?  That’s because there are laws against collecting rainwater here  - with some exceptions, which I will get to below. 

I believe we are the only state in the Country that doesn’t actively encourage rainwater collecting.  This is because the state of Colorado “claims the right to all moisture that falls within its borders” and that “said moisture is declared to be the property of the people of this state, dedicated to their use pursuant” to the Colorado constitution.  The right to this water is then based on a system of prior appropriation, and few people have water rights that are senior enough to allow them to divert water by collecting and holding it in rainbarrels or cisterns.

But wait! – I can just hear you protest now – “I heard that there was a bill that was passed that allowed us to collect rainwater!  I’ve seen ads that tell me I can!”

I know, I’ve seen those ads, too.  Unfortunately, the ad creators didn’t carefully read the bill.   Or they were confused.  And I will grant that there is much confusion about what is allowed and not allowed.   To help clarify, we had Extension Water Resources Specialist Perry Cabot write up some information on the bill (and this has been reviewed by the Colorado Division of Water Resources, so you can consider it to be accurate):

Senate Bill 09-080, which was passed by the General Assembly and signed by the Governor during the 2009 legislative session, allows limited collection and use of precipitation for landowners, under the following circumstances:

1.      The property on which the collection takes place is residential property
2.      The landowner uses a well, or is legally entitled to a well, for the water supply
3.      The landowner has (or is eligible for) a well permitted for uses according to Section 37-92-602 or Section 37-90-105, C.R.S.
4.      There is no water supply available in the area from a municipality or water district, and
5.      The rainwater is collected only from the roof of a building that is used primarily as residence
6.      The water is used only for those uses that are allowed by, and identified on, the well permit

NOTE: Rooftop precipitation collection permits cannot be issued if the water source operates under a system using an augmentation plan.  Most importantly, contact your local Division of Water Resources office for more information and detail on eligibility:

So, to further translate what that means:

If you get a water bill, you can’t collect rainwater (see point #4)… I know… bummer.

If you have a well, you can only collect rainwater for the same purposes as is identified on your permit.  So if you have a household-use only permit, you can only collect rainwater for indoor uses such as flushing toilets or watering houseplants.   More bummer.

If you’re interested in gardening, but don’t have water rights, or want to reduce your water usage, you may want to watch a webinar on no-water gardening for higher elevations: