CO-Horts Blog

Thursday, May 28, 2020

Take a Tree Walk!

Posted by Sarah Schweig, Broomfield County Extension

Community Park, Broomfield

These photos are from a Twilight Tree Walk we did in August of last year in Community Park, which lies just outside the Broomfield Extension offices. We talked tree maintenance, selection, successes, and failures. Our City Forester joined us, and it was fun to get some insider information and history on the trees in the park.

Community Park, Broomfield
While we all look forward to the time we can walk en masse through parks again, there is a version of this you can do absolutely solo on your own time, making it a perfect activity for getting outside and learning something new in our current circumstance. The trees in Community Park are part of a Colorado Tree Coalition (CTC) tree collection, and we actually used the tree collection map to plan our route through the park.

You can view available CTC tree collections at Each leaf on the map below represents a tree collection that you can explore. Below that, you can see what our map of Community Park looks like as an example. Click a tree marked on the map to reveal more information about it. You can view all the trees at once, or toggle if you’re looking for a particular tree.

Map of CTC Tree Collections
Map of Community Park Tree Collection in Broomfield

As a caveat, updating these maps is a huge undertaking, and thus they are not updated super regularly. There may be a few trees that are out of date on the map, and there are varying levels of information for each tree. Some have species bios, or even specific tree bios, and others offer little besides an I.D. Nonetheless, walking through a tree collection is a great way to get ideas and observe characteristics and species that you like.

While most of the tree collections shown on the map above are clustered around the Front Range, there are loads of other options, and they come in all shapes and sizes. If you have a favorite park, you can start with their website. Many have maps of their trees and guided tour materials available. You can check out your local community tree inventory, though they tend to be a lot more thorough and less user friendly than sources designed for public consumption. If thorough is your thing, you might enjoy the maps and data at Colorado Tree View, a statewide application where local urban and community tree inventories are aggregated and managed.

With a little bit of digging, you can find a lot of information on the trees in your community. Already have a favorite tree walk? Let us know!

Monday, May 25, 2020

The Best of Red, White, and Blue

Posted by: Alison O'Connor, CSU Extension in Larimer County

To all those who have served our county, are currently serving, or sacrificed their life: Thank you. On this Memorial Day, please know I am very grateful to all of you and your families.

My dad served in the National Guard for over 20 years and my grandpa was a WWII veteran. I am very proud for what they did for our country and proudly fly a flag in their honor. I also love the color combination of red, white, and blue! It's a great threesome. got me thinking...what are the best red, white, and blue flowers if you wanted to have your own patriotic garden? It turned out to be a really long list, so I'm just highlighting a few below. Feel free to share your favorites in the comments below!


Obviously roses are at the top of the list. What's more red than a rose? But red is a hard color--is it more candy apple red? Mustang red? I'm Not Really a Waitress red from O.P.I. nail polish? Red is a very personal color and can be subjective in the eyes of the gardener.

A very good red rose that is fitting with our theme is 'Veterans' Honor' hybrid tea. This rose actually has roots to a special Master Gardener in Larimer County, Roger Heins. Roger is a veteran and worked as a breeder for Jackson and Perkins and this is one of his introductions. Hybrid teas can be fussy, but if you want that perfect red rose, this is this one for you.
Veterans' Honor hybrid tea rose from Jackson and Perkins
If you want to add some color to your summer garden, then plant some zinnias. They are non-stop bloomers, great cut flowers, and come in many colors, including red. In the CSU Annual Trial Gardens, the top zinnia was 'Zesty Scarlet'. Another option is 'Benary's Giant Scarlet'.
Benary's Giant Scarlet zinnia
Runner up red flowers: geraniums, dahlias, tulips, petunias, cardinal flower, anthurium, poinsettias, and amaryllis.


White is simple. It's pure. White is a neutral and can be paired with anything. Fortunately there are many great white flowers:

Bleeding heart is one of my spring-blooming favorites. It reminds me of my Grandma Stoven who used to tell me a story about each part of the flower. For the life of me, I can't remember! I know it involved two bunnies, a bottle of wine, and button hooks. Bleeding heart loves cooler weather and fades when it gets too hot, but comes back reliably each year. Its cousin, the pink bleeding heart, make a good match in the garden.
White bleeding heart
Iris are another spring bloomer, and iris come in every color of the rainbow. The white bearded iris are absolutely beautiful--a very clean, crisp white. Plus, iris are tough-as-nails. They are drought tolerant and bloom their hearts out every year. Maintenance is minimal and they just need to be divided every few years.
White bearded iris
Finally, an annual that loves the heat and blooms non-stop is bacopa. Looking for a spiller for your containers and hanging baskets? Bacopa is a great choice. This little annual is covered in blooms all summer and doesn't need any pinching or deadheading. 
Runner up white flowers: Shasta daisies, Annabelle hydrangea, cosmos, sweet alyssum, Spring Snow crabapple, and datura.


Did you know the Pantone Color of the Year is Basic Blue? Yep, so now you can be patriotic AND trendy in your garden, if you plant blue flowers. Blue is a tough color--there's not a lot of true blue flowers, but breeding is getting better and there are many that are close enough. A couple options:

Lobelia. The darling of hanging baskets. The good news about lobelia is that it's being bred to be more heat tolerant. In the past, lobelia would melt with hot weather and all that would be left in your baskets by August were petunias. (Note: there are some very good white lobelia too!) Lobelia blooms all.the.time. 
Blue lobelia. The flowers are just getting started.
My co-worker just texted about love-in-a-mist the other day. She loves it and wants more. With fennel-like foliage, this annual is a great cut flower and will reseed freely in your garden. It does prefer some moisture. After it blooms, the seedpods add additional interest.
Love-in-a-mist (photo from
Speedwell (Veronica) is another great blue...with shades of purple. This perennial can range in height from just 12" to over three feet, depending on the cultivar you choose. Pollinators love speedwell and will attract butterflies, bees, and hummingbirds. After the first bloom, cut back the plant to encourage a second (smaller) set of flowers. 
Dark Moody Blues speedwell
Runner up blue flowers: lupine, foxglove, Endless Summer hydrangea, delphinium, Himalayan blue poppy, lily of the Nile, and forget-me-not. 

Red, white, and blue also pairs well with greens, so don't forget those foliage plants! 

Thursday, May 7, 2020

Early blooming shrubs are rock stars in the pollinator garden

By Irene Shonle, Horticulture Associate, El Paso County

Have you ever felt sorry for a bumblebee who has emerged from her long winter’s nap on a warm spring day?  She buzzes around, looking for a little energy to replenish her stores, but there’s nothing in sight.  Or what about a Mourning Cloak butterfly?  They always seem to be the first butterfly out. Colorado plants in general are slow to wake up in the spring, and our spring weather is famous for being a roller coaster, so most plants play it safe and don’t bloom too earl, leaving early insects without any food.

Enter native shrubs – the rock stars of the early pollinator garden.  Even while most perennials are still sleeping, if you have some key native shrubs planted, you will be able to provide crucial food to those pollinators lured out on an unseasonably warm day.

The earliest to bloom, in my experience, are:
Mahonia repens - Creeping Mahonia
Creeping Mahonia (Mahonia repens) is a small groundcover. It has tough leaves that resemble holly, turn bronze-red in winter, and stay that way until spring.  In spring, bright yellow flowers are some of the first to burst into bloom, and they smell like honey. This is followed by blue berries in the fall (not very tasty, but good for wildlife).The plant can even tolerate dry shade, which is a big bonus!

American plum - Prunus americana

American plum (Prunus americana) is mid-sized shrub that sometimes tempts fate by emerging too early. It was blooming this year along the Front Range before the April 12 cold snap, and in many places, the flowers froze. However, in the majority of years, the flowers do just fine, and they smell wonderful.  The bushes produce orange to purple small plums with variable flavor – wildlife will eat them if you don’t use them in preserves.  It prefers full sun, but can take a little shade – and make sure to plant it where you can enjoy the smell.  It sometimes suckers.

Three-lobed sumac (Rhus trilobata) has early yellow-green flowers that are relished by bees. This is a tough shrub that can handle heat and drought, has reddish ‘berries’ that are an important winter food source for birds, and reddish-orange fall color.

Golden currant - Ribes aureum
Golden currant (Ribes aureum) is a smaller shrub with yellow flowers in the spring. Some varieties (var. villosum – formerly Ribes odoratum) smell like cloves. Golden and wax currants (R. cereum) are some of the first flowers for hummingbirds, but other pollinators such as bees enjoy them, too. Bonus: edible currants later in the summer (for you or for birds), and red fall color.

Slightly later we have:

Chokecherry - Prunus virginiana

Chokecherries (Prunus (Padus) virginiana) is a larger, suckering shrub with a host of habitat benefits. The fragrant white flowers are great for the pollinators and the plant overall is a good host plant for butterflies and other insects. The purple berries attract birds, and humans admire the red-colored fall leaves.  This is not a shrub that works well as a single-trunked tree due to the suckering; it is better as a hedge where you have a little room.

Serviceberry - Amelanchier alnifolia
Serviceberry (Amelanchier alnifolia) has many pollinator-friendly white flowers, followed by blue berries (good for people and birds to eat) and reddish fall color. 

These shrubs are awesome for pollinators, and also for birds.  And, importantly, will look great in your yard!

Tuesday, May 5, 2020

Preparing pots to re-plant for the season

Enjoy a guest post from Adams County Colorado Master Gardener Ted Lopez:

It is time to prepare our pots for planting day.  This entails cleaning the pots and refreshing the soil with a small amount of compost and topping off the soil in the pot.  Besides our gardens, we have around 40 pots of plants to add color and texture to our gardens.

Here are some of the pots that need to be worked.


I use a potting mix and mushroom compost mixture to refresh the soil.

I then empty a pot into a wheelbarrow and combine the mixture.  I usually empty 2-3 pots out at one time.  This cuts down on mixing time. Note: if you have had any disease issues with the plants you grew it's not a good idea to reuse the potting soil. Vegetables should always be started with fresh media. 

With the dirt out of the pot, I clean and inspect the pot.  I clean out the drain holes as needed. Drainage holes are necessary for any pot to ensure good moisture content in the pot. If your pot doesn't have them you can drill several holes in the bottom. 

Some of my pots have inserts.  I clean them and return to the pot.  This pot is ready to be refilled.

Since our other pots do not have an insert, I will need to make one.  We use 1/4 inch thick compressed coconut shreds.  We have used a wide variety of other types of drainage control for our pots but have found this to be the best.  It's light weight, durable but normally needs to be replaced each season. Inserts are useful for keeping the potting media from falling out of the pot. 

I need to measure to cut a appropriate size for the pot.  The coconut shred material comes on a roll.  I use a good set of garden scissors to cut the material.  

Cut a square (trying to cut a circle is labor intensive and not worth the time and effort.).  I then insert it in the pot, and it is ready to be filled.  There is no need to add rocks or other material to the bottom of a pot to "improve drainage". The soil has to become saturated before water will move into the rock at the bottom. If you're using a really large pot you can add material to the bottom to reduce how much soil you need to use. 

The end product. These pots are ready for planting day.  

Monday, May 4, 2020

Annual Weeds

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

Cheat grass, gone to seed
 Getting rid of weeds sounds like a simple idea but most of us know it is easier said than done. This post talks about controlling annual weeds, not perennials. Always try to identify the weeds you are dealing with so you can plan the most effective attack plan.

As I take my socially distanced walks around the neighborhood I am always disheartened at the sheer volume of annual weeds I see taking over peoples yards, gardens, rocked areas, and flower beds. It isn’t that I think my neighbors don’t care, I think many of them do, it is just such a hard problem to cure.

The annual weeds are some of the worst because they come up in the spring when we are all dying to see green. They give us hope that the dead patch in the back alley or next to the driveway is finally filling in with the grass we want, and just a few months later we are irritated by the nasty seed heads stuck in our socks and pet’s fur or the dead brown patch they become.

Often times killing the annual weeds (be it Blue Mustard, Yellow Mustard, Cheat grass, Green Foxtail, Henbit, Kochia, Russian Thistle, or others) won’t do anything in the overall control of the weeds. Annuals are the quick and dirty plants of the world because they go to seed so quickly, often before we really have the chance to find and identify them all.
Foxtail, gone to seed
Instead of having it in your mind to kill annual weeds, have it in your mind to keep them from spreading seed. Since an annual weed only lives for a year and then dies, it’s entire specie depends on producing enough seeds to repopulate next year. This can be achieved (or at least attempted) in several ways.

Weed Early: If you can pull or otherwise root up the weeds when they are very small (less than 3 inches, and no sign of seed heads) they will likely die without reproducing (win!). If you don’t mind the look of little weed bodies all over, you can even leave them on the ground. No bagging for you! Herbicides are also an effective choice at this point (always read the label on herbicides! The Label is the Law).

Weed Often: Sometimes with cold and warm weeks and spring rains we will have “flushes” of new weeds coming up. So take a walk around your yard or property fairly frequently, it’s good for your health and also lets you keep on top of what is sprouting up.

You say you see weeds with seeds? It is easy to fall behind on weed watching. I know it happened to me this year. If you start seeing taller weeds or weeds with seed heads you know you have missed the easy window. I really am sorry for you because things get a little more labor intensive now.

Herbicides: If you were all for using herbicides, that window has closed, put down the sprayer. If you kill a happy green weed with seeds you will have the satisfaction of seeing it get sad and brown and die, but the seeds will survive your chemical assault and next year you will be back where you started.

Don't leave a pile of weeds with seeds!
Pulling: Pulling is a solid option. Annual weeds are usually easy to pull up and can be bagged and thrown away. Since the seeds exist try not to shake the pulled plants too much. You have to bag and throw them away at this point.

Mowing with a bag: If you just can’t possibly pull all the weeds consider using a lawn mower with a bag to collect your cuttings (and throw the mowed contents away). This method is sloppier than hand pulling and bagging but will collect more weed seeds than doing nothing. This works from some weeds but less on others, Kochia for example will just grow lower to the ground and form a mat of seed producing weeds.

Keep Weeding: You will likely need to do some level of weed control every year. Seeds from deeper underground will start to grow, wind will bring seeds from your neighbors, a rogue Kochia tumble weed will make its home in a corner of your fence and rain seeds on the ground, the possibilities are endless. But keep your head up, after the first year or two of keeping the seeds at bay you will probably see a good reduction in the weeds that come up, and after that hopefully you can work proper weed management into your schedule.

Blue Mustard with seeds
Young Kochia, not seeded yet
Young Cheatgrass, not seeded yet

Tansey or Yellow Mustard with seeds

Prickly lettuce, no seeds