CO-Horts Blog

Tuesday, September 29, 2020

2020 "Best Of..." Winners from the Colorado State University Annual Flower Trials Announced!

Posted by Dr. Jim Klett, Colorado State University, Department of Horticulture and Landscape Architecture

Approximately ninety five professional and advanced Master Gardeners rated over 1,150 flowering and foliage plants over the week of August 3-8, 2020. We were not able to have an official evaluation day due to COVID 19 and University ruling on not having public gatherings on University property.

The garden is planned and maintained each year by the Department of Horticulture and Landscape Architecture with guidance from a committee of growers, flower seed companies, and public garden horticulturists. 

The following are the winners for "Best of Show", "Best New Variety", "Best Novelty" and "Best Container". For more information on these and other outstanding annuals from 2020 trials visit

Best of Show – Dahlia ‘Lubega® Dark Velvet’ from Benary+

This was a ‘show stopper’ due to the strong contrast between the dark purple/velvet foliage and beautiful bicolor blooms. Plants were extremely attractive all by themselves with the dark foliage coloring and uniform compact growth habit.  The prolific flowers were held high above the plants to create maximum show. Blooms had single petals which attracted many bees. Plants did not have any sign of powdery mildew even late in the season.


Best Novelty – Colocasia ‘Heart of the Jungle™’ from Proven Winners

This plant makes a dramatic statement to any landscape with its large, dark foliage. The impressive size and shape creates a very tropical and exotic appearance. It is grown for the beautiful foliage which makes a great structure plant in the garden. It does best in full sun.


Best New Variety – Centaurea ‘Snowy Owl’ from Terra Nova

Unique silvery foliage made this plant a standout in the garden. Large, velvety leaves added an interesting textural element.  The beautiful gray color made a great combination with other plants. It was highly visible in the garden and very uniform.


Best Container – Petunia ‘Bee’s Knee’ from Ball FloraPlant

The abundant flowers and great two tone yellow color provided exceptional flower power on very vigorous and well branched plants. It was noted for having the best yellow of any petunia in the trial.  The color held up very well in the high light intensity of Colorado. 

Thursday, September 24, 2020

Preparing an asparagus bed


By Irene Shonle, El Paso County

So, your gardening season may have been abruptly shortened by the Sept 8/9 cold snap, but as the days warm back up, you can begin to think about next year – a gardener is ever optimistic, right?

One of the things I am planning for next year is to plant asparagus – I will put them in a sunny corner of the yard next to my rhubarb and horseradish, in my perennial edible section.  Perennial edibles are very rewarding, in that if you plant them well from the get-go, they will reward you for decades to come.  I am prepping my asparagus bed now in the fall to make life easy for me in the spring when the crowns are usually more available.

To plan for an asparagus bed, take these things into account:

1.      How many people will you be feeding?  Are you crazy for asparagus, or more moderate?  Plan on 5 crowns per person on the low end and 20 per person for those who can’t get enough.

2.      How much room do you have (in a sunny location with good soil)? Ten crowns need about a 4-by-8-foot bed (Rows of asparagus should be at least 2 feet apart, allowing two rows to fit in a 4-foot wide bed).  Asparagus is frequently sold in lots of 25 crowns, which would require about 80 sf.


Because asparagus is a one-and-done investment, it is worth taking a little time to prepare the bed properly.  First, make sure you choose a sunny spot – asparagus will be more productive in full sun. The site also has to be well-drained. If you see pooling water after a rain (that sticks around a while), that will not be a good site. You could choose to plant asparagus in a raised bed, if that is your only site option.


Grass in bed

Asparagus is sensitive to any competition from other plants, so remove all grass, weeds, and any other existing vegetation from the planting area, including roots.  If the area you want to plant is quite weedy, and has been so for a while, consider taking next year to get the weed situation under control, and planting the following spring.


Asparagus likes rich, non-acidic soils. The last is usually easy to provide in Colorado, but the former requires some soil amendments.  Loosen the soil to a depth of 6 or 8 inches over the entire planting area with a tiller or shovel. Spread 2 to 3 inches of compost or well-rotted manure over the planting area and mix it into the soil.  If you want to protect the bare soil from weeds, mulch with leaves or weed-free straw. You are now done for the winter!  Congratulations.


Come spring, you will need to order your plants online, or purchase from a local garden center. It’s best to get the varieties where the spears are all-male, as they are the most productive, since they do not spend any energy producing seeds.


Dig a trench 12 inches wide by 6 inches deep where the crowns are to be planted, keeping the rows about 2 feet apart. Plant crowns about 12 inches apart. Spread the roots and cover the crowns with two inches of rich soil, amended with compost or a slow release fertilizer. As the spears begin to grow,  fill the trench with soil two inches at a time.


At this time, you need to muster patience - you just water and wait.  One of the hardest parts of planting asparagus is to refrain from picking anything the first year. Newly planted crowns should be left to form "ferns," which provide food for the roots. The second spring after planting, a few shoots can be harvested, but just once or twice. Leave the rest to feed developing roots. The third year , however, is where your patience pays off, and you can harvest away!


Asparagus should be fertilized in the spring just before spears emerge and again right after the last harvest in June for older plantings. Use 1 to 1.5 pounds of an all-purpose garden fertilizer, such as 10-10-10, per 100 square feet.


Pull or carefully dig any weeds that come up in the beds to keep out competition.

Monday, September 21, 2020

Turning the page on a successful 2020 grape season in Colorado

Posted by: Miranda Ulmer, CSU Viticulture Extension Specialist  

With grape harvest coming to an end, we are reflecting on what a year 2020 has been for us all, even the grapes in Colorado! However, despite many challenges, it has been a successful year. It all started when the 2019 harvest ended abruptly due to a cold front moving across the state in the beginning of October while fruit was still on the vines. Not only did this compromise the 2019 harvest, but it could have potentially affected the 2020 season as well. However, since we also experienced a freeze in April, just as the buds were about to break, it is hard to determine which event could have caused damage. You may recall that the freeze that occurred in April is what killed the majority of Colorado’s peach crop. The grapes were luckier in that they break bud later than the peaches, so only the early varieties were potentially compromised, and to a much lesser degree than the peaches.


Just as some of us wish we could fast forward through 2020, this season was the earliest season on record for grapes in the last 20 years. This can largely be attributed to the hot summer we experienced where it felt as if it didn’t drop below 100 degrees for two months straight. I had forgotten what 80 degrees felt like, but thankfully I have recently been reminded 😊.


As icing on the cake, the Pine Gulch Fire began burning 18 miles North of Grand Junction just as harvest was about to commence this year. The Grand Junction/Palisade region is home to Colorado’s largest grape growing region, and based on feedback from long-term industry members, has never experienced a fire of this magnitude in this close of proximity before. Smoke from nearby wildfires has the potential to cause smoke taint in grapes and wine resulting in off flavors and aromas. Luckily, preliminary results have shown that samples from the Grand Valley are below the threshold of concern for smoke taint. We (CSU and Western Colorado Community College) are collecting data from all across the Grand Valley to better understand how smoke taint can be prevented and/or managed in the future.


A smokey harvest at CSU- Western Campus 
Grand Junction, Colorado

Colorado grape growers are used to facing the many challenges that come with growing grapes in Colorado, including the cold winters, unpredictable spring and fall temperatures and extremely dry conditions. 2020 involved a few more unexpected challenges, but growers across our state rose to the occasion. Hats off to the Colorado growers and winemakers for another successful grape season. Support local & drink Colorado wine!

Thursday, September 17, 2020

Pueblo Edible Landscapes Project

By Sherie Shaffer, Horticulture Agent, CSU Extension-Pueblo County

This summer, our Master Gardeners in Pueblo County didn’t have a lot of chances to volunteer in the community due to COVID-19. Luckily they were able to participate in a few COVID safe projects, one of them being a partnership with a local organization, The Pueblo Food Project, called the Edible Landscapes Project.

This project is an initiative to provide fresh produce to anyone who wants or needs it, and also to provide education to the community on growing food.

The project had three public sites, each with 2-3 volunteers working at them. Through the PFP, the volunteers were given a budget to buy plants and prepare their planters. Edible plants were added to each site, and signage was added to encourage passers by to take any produce that they wanted. Any excess produce is being donated to local food banks.

Later on in the year, signage was added that explained what was growing the plots and gave information on how to use it, nutritional value, and growing tips. Videos were also made that showed off the gardens and promoted them to the community.

Community members definitely took advantage of the fresh produce up for grabs. I live just down the street from the Mineral Palace Park site, where I walk almost daily, and have seen countless people picking produce and just marveling at the magnificent plants growing there.

We are at the end of the season, and we did have a freeze a couple of weeks ago, so the plants are starting to lose their luster a little bit, but that being said they do still look pretty good. Here are some photos of one of the sites that I took today, complete with a photobomb by my bloodhound, Layla. To see the gardens earlier in the year and get a personal virtual tour from our Master Gardeners, check out the videos linked above.

Thursday, September 10, 2020

Plant Hardiness is More than a Zone Number

Posted by: Kara Harders, Peaks and Plains Regional Small Acreage Specialist

If you have lived in Colorado for a while you have probably lamented (or heard people lament about) the constant influx of new residents. Colorado really is a state unlike the rest. It isn’t hard to work out why so many people find it appealing to live here: mountains, 300 days of sunshine, low humidity, all four seasons of the year, boating/rafting/kayaking, hunting/fishing, wide open spaces, the big city, I could go on but I think I’ve made my point.

If I had to make a list of drawbacks in Colorado it would be short – wildfires, drought, and home prices come to my mind first, but we are currently (9/9/2020) experiencing one of our phenomenons that is less glamorous: wacky early/late cold snaps.

While Colorado is not unique to this issue, it is among the most common places for it to happen, and it’s hard on plants. It can make plant selection tricky too, have you ever used or seen the Plant Hardiness zone map?

Plant Hardiness Zone Map

Image courtesy of USDA-ARS

This map is super handy for identifying plants that can grow in different areas based on the “Average Annual Extreme Minimum Temperatures”, essentially, how cold can the plants handle. This is useful information and can help guide decisions about what to plant, where to plant it, and if you can expect it to need additional protection.  What this map doesn’t have is a “Areas that Experience Strange Unpredictable Temperature Swings During Odd Parts of the Year” score, I don’t think there is a handy chart for that.

An example of what I am talking about is the Kiwiberry or Cold Hardy Kiwis. The University of Minnesota (in Minnesota, which according to the map, is certainly cooler than Colorado) has been researching the plant, experimenting with species and cultivars, and looking into growing practices for more than 30 years. It does well enough in Minnesota they even looked in possible invasive qualities of the plant. However, when grown in Colorado, the Kiwis failed (even in high tunnels). Why is that?

It is because of days like Tuesday and Wednesday of this week when we experienced a 70 degree temperature swing in 48 hours, or in mid-April this year when it got down to single digits after being in the 70’s the week prior.

While the Kiwis are hardy to -20 degrees, they cannot handle the climactic whiplash that is Colorado. They need an intercontinental climate, an area where it gets cold then stays cold; gets warm then stays warm. In the Kiwi’s case, the warm spells in the late winter and early spring trick them into budding out and blooming.  In experiments done in Hidden Mesa (Douglas County) the late spring frosts kill not only the blossoms, but often the vines too. (Photo to upper right: Kiwiberry, photo by University of Minnesota) 

Similar problems arose in the fall when the first hard frost can happen before the plants have had time to harden off, often killing them. Even in high tunnels the plants slowly died back to nothing, while plants such as raspberries did fine. 

Try to keep in mind the effects late/early freezes can have on perennial plants. Even plants that are designed to handle the swings can suffer when they are too dramatic, and plants not designed for the shifts often don’t stand a chance. To better your odds, try to research plants and varieties proven to do well in our special climate. This is a link to a PowerPoint by Andy Hough (thanks Andy!) from Douglas county with tons of information on hardiness specific to the front range:

Friday, September 4, 2020

Weather Rodeo

Posted by: Lucinda Greene, Arapahoe County Extension

The weather promises to be a wild ride for the Denver metro area starting Tuesday after Labor Day.  Remember the polar vortex in November 2014?  The bomb cyclone in March 2019?  The mini-polar vortex in October 2019, and the extreme temperature changes in February 2020, and April 2020?  By now, we are becoming familiar with the uneven weather patterns as seasons change along the Colorado Front Range. 

This weather can wreak havoc on the plants in the landscape.  Especially those you have cared for all season long!  Generally, if plants have been properly cared for, and are not under drought stress or pest or disease pressure, trees, shrubs, and perennials can handle these early frosts or freezes in September.  However, because we typically have another month before we put our vegetable and annual gardens to bed, you can take steps over the weekend to limit damage to these plants and still enjoy a beautiful fall harvest.

Pumpkins are a warm season vegetable crop that could benefit from being covered during an early season cold snap. Photo: Lisa Mason  

Follow these tips to give your plants a fighting chance to survive next week’s cold snap:

  1. Trees and shrubs – give all woody plants a good drink over the weekend or on Monday. The temperatures in the Denver area are expected to be hot – the high 90’s.  Trees and shrubs can handle the stress from a rapid temperature change better if their root systems have adequate water.  Moisture in the soil also helps moderate soil temperatures and helps protect plant root systems because water has a high heat capacity. 
  2. Perennials – give perennials a good drink like trees and shrubs.  Most perennials suited for Colorado’s Front Range (USDA Zone 5A to 6A) can handle these temperature swings. 
  3. Vegetables -  Depending on how cold it is expected to get in your area, harvest and cover warm season vegetables.  Frost cloths, bed sheets, drop cloths, or blankets make suitable covers for vulnerable plants including tomatoes, zucchini, peppers, cucumber, and squash. Use stakes to keep the material from touching foliage.  Remove the cover promptly in the morning when temperatures rise.  
  4. Vegetables – Depending on how cold it is expected to get in your area, you may wish to cover cool season vegetables like chard, spinach, kale, and lettuce. Root vegetables like beets, carrots, onions, and garlic should be okay without a cover.  
  5. Annuals in landscape beds – Cover with a cloth similar to warm season vegetables. 
  6. Annuals in hanging baskets and containers - Water the soil in hanging baskets and containers well.   Remove hanging baskets from their hooks, and store them indoors along with containers if possible, or group hanging baskets and containers together outdoors and cover with a cloth.  If containers and hanging baskets can be gathered together, store on the ground and cover, taking advantage of warm soil temperatures to keep air around these plants above freezing. 
  7. Finally, after this unanticipated early cold snap, take stock of your landscape.  Do you have frost pockets, or micro-climates that show evidence of higher than normal freeze damage, and therefore colder air accumulation?  Swales, or wide open exposures can experience colder temperatures away from sidewalks and buildings.  Consider moving desirable plantings to other areas of the landscape if you notice a consistent problem.  Or, consider choosing different plant material that withstands these inevitable temperature swings.  Native plants are a great option, since they have evolved in this tricky climate. 
  8. Call your local Master Gardener office if you have additional questions.  They are standing by to help! 


Thursday, September 3, 2020

Drought and Bees


By CSU Horticulture Agent, Linda Langelo

Photo credit: Svarun

How are you surviving in these 100-degree days?  I am hot.  How about you?  Have you ever thought about how the bees are doing in this drought and heat?

Drought is very stressful on bees as it is with all other living beings.  Without water, life ceases to exist.   Bees need water daily.  Bees do not store water. They need it for themselves and for the hive.

Here are a few reasons bees require water daily:

  1.   Water is essential for temperature and humidity control.  The bees bring water to the hive for the young bees developing in the brood.  The evaporative cooling in the hive keeps the temperatures down.  The nest temperature is best kept around 35 degrees Fahrenheit. Food for the brood is watered down to 70% water and honey pollen.  The worker bees control the humidity of the hive. 
  2. Water is essential for utilized stored food.  Bees use the water to dilute the food because the glucose content may be too high.
     3. Water is essential for the nurse bee who needs water for their hypopharyngeal                   glands can produce jelly for the larvae.
    4.  Water is essential for digestion. 

Just how much water does a colony require in a day?  According to Bees for Development, on hot days bees may collect several gallons of water every day. One bee can make up to 50 trips a day to collect 25mg of water.  That sounds like a lot of work for a worker bee!

How do the bees find a nearby source of water?  Since bees control the humidity of the hive, they are good at finding sources of water by the higher humidity in the air which is above a water source.  Shallow sources of water may be missed because they do not increase the humidity in the air as much as does a deeper source of water.  Bees can drown in deeper sources of water.  Providing a way for them to reach the water safely without drowning is key.

Bees are also sensitive to odors.  So, if you are providing a source of water, make sure it is free of chemicals. 

How can you help provide water for the bees? 

1)Get a container that is shallow and wide.  Put stones and/or twigs in the water for bees to rest on or the bees will drown. 

2)Be sure to change and/or add water daily. 

3)Place the container close to the hive. 

If you have a birdbath, bees can land on the edge and drink water safely as shown in the photo below along with the other photos of watering holes for bees:

     Photo credit: Nicolefoto/iStockphoto – Science News for Students


                 Photo credit: Christine Casey,  UC Davis The Bee Gardener, Bees on a piece of cork

     Photo credit: Christine Casey, UC Davis, The Bee Gardener