CO-Horts Blog

Friday, October 28, 2022

Hallowe'en Herbage

 Posted by John Murgel, Douglas County Horticulture and Natural Resources Agent

Every plant on earth wants you dead.  They just haven’t all figured out precisely how to do that.  Yet.

 Because Hallowe’en is on the way soon, we thought we’d take the next couple of blog posts to talk about some terrifying plants.  Mind you, lots of frightening flora are out there—but we’re talking about the really, really scary ones. 

 What makes a plant terrifying?  Certainly some plants have long human associations with the macabre (the cannibal tomato, Solanum uporo, comes to mind), some are ugly to look upon or repulsively stinky (corpse-flower cologne, anyone?), and (many) more are poisonous to some degree.  We’re going to focus on the poison kind.

 Plant poisons are typically intentionally manufactured compounds that are designed for defense.  Some are aimed at insects, some at vertebrate herbivores, still others at fungi or other plants.  Many of these compounds have been hugely beneficial to human health in the form of pharmaceuticals or precursors thereto.  Others have been harnessed to attack insect pests in agriculture.  Still more have been used by humans for their mind-altering effects, or to flavor food.  With plant poisons, it’s a game of dosage.  Just the right amount can be useful.  Take too much though, and it could be “game over.”

  In the next post you’ll read about one of the most famously poisonous plants.  You might run across it, and you might not.  Here, though, are some of the monsters that could be lurking in your home, perhaps at this very moment

green beans
 1. Beans.  Many members of the bean family are famously poisonous—and the common bean (Phaseolus vulgaris) is among them!  Beans (which are the seeds of the bean plants) contain defensive compounds known as lectins that can really cause trouble in mammalian digestive systems.  A few undercooked (or worse, raw) dry beans can provide a dose of lectins large enough to cause intestinal bleeding and “circulatory collapse.”  Thankfully, adequately cooking the beans will destroy the toxins—just don’t serve them up al dente! (Not all beans produce the same amount of lectins and not everyone is equally sensitive; Lima beans and kidney beans pack the biggest punch among commonly eaten varieties).

raw almonds

 2. Almonds and Apricots.  The rose family also contains many poisonous members, and many of those are plants that produce fleshy fruits and seeds that people like to eat.  The poisons in this case are cyanogenic, meaning that they generate cyanide once broken down—in the case of these plants, in the digestive tract.  Apricot seeds (found inside the central pit) are the most poisonous.  Several published cases report fatal and near-fatal poisonings from apricot seeds, which have become popular as alternative medicines.  Most almonds do not produce much of the compounds and are easily processed by the body, but bitter almonds (Prunus amygdalus var amara) produce more.  As few as five bitter almonds can produce fatal cyanide poisoning.  

3. Potatoes.  You may know that potatoes are members of the nightshade family (along with tomatoes

potatoes in soil

and eggplant).  All parts of potato plants contain toxins known as glycoalkaloids; usually potato tubers contain very low amounts. However, differences exist between environments and among tubers of different ages or storage histories.  Eating green potatoes or potatoes that have sprouted can be risky—poisoning is unlikely to kill you, but can cause days (yes, days) of abdominal disfunction, and at higher doses low blood pressure and neurological disorders. Unlike the lectins in beans, alkaloids are only minimal affected by cooking. On the bright side, some of these spud-borne compounds have shown promise as anti-cancer and anti-viral agents. 

 I don’t know about you, but I won’t be looking at my fries the same way again.


Tuesday, October 25, 2022

CSU Relentless Gardener Podcast 
By CSU Horticulture Agent Linda Langelo

 Photo credit: Wikipedia, Mt. Elbert

As a gardener in Colorado, are you relentless in your efforts? Want to know how to improve
as a gardener? Tune-in on Spotify and listen to our horticultural topics. Let me share with
you the topics that have been published throughout this year:

With guest speaker CSU Horticulture Agent, Lisa Mason from Arapahoe County.

Turf Renovation:
With guest speaker, CSU Turf Specialist Tony Koski.

Turf Problems:
With guest speaker, CSU Turf Specialist Tony Koski.

Spotted Lantern Fly:
With guest speaker, CSU Horticulture Agent, Lisa Mason from Arapahoe County.

Pollinator Habitats:
With guest speaker, CSU Horticulture Agent, Lisa Mason from Arapahoe County.

Native Bee Watch:
With guest speaker, CSU Horticulture Agent, Lisa Mason from Arapahoe County.

Japanese Beetles:
With guest speaker, CSU Horticulture Agent, Lisa Mason from Arapahoe County.

Emerald Ash Borer:
With guest speaker, CSU Horticulture Agent, Lisa Mason from Arapahoe County.

Beneficial Insects:
With guest speaker, CSU Horticulture Agent, Lisa Mason from Arapahoe County.

High and Dry Gardens:
With guest speaker, CSU San Miguel Basin Extension Director Horticulture, 
Natural Resources, Agriculture, Family Consumer Sciences, 4-H Youth Agent,
Yvette Henson.

Seed Libraries:
With guest speaker, CSU San Miguel Basin Extension Director Horticulture,
Natural Resources, Agriculture, Family Consumer Sciences, 4-H Youth Agent,
Yvette Henson.

Benefits of Trees:
With guest speaker, CSU Horticulture Agent, Alison O'Conner from Larimer

Caring for Your New Tree:
With guest speaker, CSU Horticulture Agent, Alison O'Connor from Larimer

Choosing the Best Spot for Your Tree:
With guest speaker, CSU Horticulture Agent, Alison O'Connor from Larimer 

Tips for Tree Selection in Colorado:
With guest speaker, CSU Horticulture Agent, Alison O'Connor from Larimer

Grow & Give: Past Results:
With guest speaker, CSU Statewide Master Gardener Coordinator, Katie Dunker.

Grow & Give What Does Grow & Give Have to Offer:
With guest speaker, CSU Statewide Master Gardener Coordinator, Katie Dunker.

Grow and Give: How Did Grow and Give Start:
With guest speaker, CSU Statewide Master Gardener Coordinator, Katie Dunker.

Future topics coming soon on the Sustainable for Life Program, Cut Flowers,
Fruit Trees, Season Extension Trials, The Ute Garden, Cool Season Crops and much more.
Stay tuned.

An equal access and equal opportunity University.

Tuesday, October 11, 2022

Creative Containers for Fall


By: Amy Lentz - Home Horticulture Educator - CSU Extension, Boulder County

It’s official, fall is finally here and cooler temperatures are ahead! As your summer annuals are beginning to look tired or may have stopped blooming altogether, now is the perfect time to revamp your flower containers.

Chrysanthemums, or more commonly just called mums, are probably the most common plant we think this time of year. There are two main types of mums, those sold inside of a florist or grocery that are not cold-tolerant (not hardy) and those that are sold seasonally outdoors which are cold-tolerant to our area (hardy mums). You will want to choose the ‘hardy’ type so that they can withstand the lower temperatures and can even handle a light frost. Choose plants with tight, unopened buds for longevity of the blooms. If we have another mild winter, you can plant your mums in the ground at the end of fall and there’s a slight chance it will come back again next year if they are the hardy type. Mums come in a wide range of colors including orange, red, yellow, purple, white and even burgundy so you can choose your favorite and mix them with other seasonal plants to create a festive display.

Chrysanthemums make a nice addition to your fall display!

When creating your fall containers, you can follow the classic “filler, spiller, thriller” method to get both height and fullness to your arrangement.

Save money by reusing annuals from your summer containers such as snapdragons, dusty miller, and marigolds if they are still holding up well. Other fall annuals to add to your containers include fall aster, ornamental cabbage, pansies, violas and even Swiss chard or kale (which are both tasty, too!). You might also find good deals on perennials this time of year which can also be added to your containers to add interest. Yarrow, butterfly bush, coneflower, black-eyed susan, and blanket flowers all have neat seed heads that can be interesting even after their petals are gone. If you want to get really creative, you can work in some succulents or small ornamental grasses to make it more unique. Tie it all together by displaying with pumpkins, gourds, and attractive branches from red-twig dogwoods, hawthorns or evergreens.

Once you have gathered your plants and are ready to put the container together, follow these general guidelines to help your containers last until the end of the season:

1.       You can use a number of different container types including plastic, glazed ceramic, terra cotta, wood crates, etc. Each will differ in their watering requirements and all should have at least one drainage hole at the bottom.

2.       Refresh the potting media by loosening it, adding 50% new mix and removing any old plant roots from the container.

3.       Be sure to break up any rootbound plants by gently teasing/pulling the root system apart with your fingers before planting. Even though it’s cooler, the plants will still grow but you can use a bit tighter spacing since the season is short.

4.       Add slow-release fertilizer at planting and water the container thoroughly once all plants are in place.

5.       If you are using perennials and want to overwinter them, you can plant them in the ground by late October and mulch well. Or you can simply bring the containers into an unheated garage or cool, dark space. Remember to water occasionally throughout the winter.

Example of a fall container using ‘Mesa Yellow’ blanket flower, burgundy and pink mums, orange marigolds, ornamental kale and a vining cold-hardy succulent. 

Containers are a fun and easy way to decorate for fall and make the most out of your space for the full growing season! For more information on fall gardening, visit or contact your local CSU Extension Office. 

Thursday, October 6, 2022

Favorite Fall Wildflowers

 by Yvette Henson, San Miguel Basin CSU Extension 

I am a person who transitions slowly but our extended fall season, with its azure-blue skies and golden- aspen, fall-color explosion eases the transition from glorious mountain summer to snowy, gray winter.  The tops of the mountains, where the tundra is, are green from June to mid-August until high-elevation frosty nights put an end to the fleeting summer wildflower show. Then the tops of the mountains turn from green to gold and finally to white.  

I'd like to share of few of my favorite wildflowers that lead up to and last through the seasonal shift from summer to winter.  I am cheered to see them return, year after year.

Gentiana parryi, Parry’s gentian, signals that summer is soon-to-end. The goblet-shaped blooms are a true blue, which is rare as a flower color.  It can be found July through September on the forest edge, in moist meadows and along stream banks at elevations between 7,500 and 13,200 feet. Look closely at the bloom to appreciate the detail!

A close-up Gentiana parryi bloom
(photo Yvette Henson)

Gentiana parryi plants
(photo Yvette Henson)

Rudbeckia laciniata var. ampla, cut-leaf coneflower, comes into bloom about the same time. I admire its stature, it's deeply lobed leaves and its domed center-disk with droopy ray flowers.  It weaves a ribbon along the creek bank of one of my favorite jeep roads.  It also grows in damp ditches.  It can be found from 5,000 to 9,000 feet elevation, late June through September.  I’ve collected seeds of this plant for our seed library but haven’t tried them at home because of my dry site.  However, I saw them featured in a British gardening publication, where they were grown in ‘regular’ garden conditions so I will give them a try next year.

Someone else enjoys Rudbeckia laciniata var. ampla almost as much as I do! 
(photo Yvette Henson)

Solidago velutina, velvet goldenrod, grows on its own in my yard.  It grows along the path to my door where it welcomes me home on summer evenings. I often sit down beside it just to watch the many pollinators enjoying its bright yellow blooms.  Velvet goldenrod begins blooming in late July and is still blooming at my house today.  When its flowers all wither, I know it is almost winter.  It does well in dry soil at elevations from 5,500 to 10,500 feet. 

Solidago velutina
(photo Yvette Henson)

There is an unidentified (to me) 'aster' that blooms all along the highway, through a local mountain town at almost 9,000.  Maybe it is really an Erigeron?  Or maybe it was a cultivated aster that escaped?  I have yet to figure it out.  The ray flowers are a deep purple, a much richer hue than the similar purple fall 'asters' that grow in other mountain communities near me.  I look for this particular aster each year.  I always say I am going to collect seed but since it’s an hour and a half drive from home, all its seeds have usually blown away before I make it back.

My favorite fall 'aster', growing in one of my favorite mountain towns
(photo Yvette Henson)

Gentiana algida, arctic gentian, blooms in the high alpine tundra after most of the summer blooms have faded.  The Flora of Colorado says it is one of the last plants to bloom in the alpine and can be found July-September, 10,000 to 14,000' elevation. The entire plant is rarely more than 6” tall, including the blooms, and to me it's like a magical fairy plant with its comparatively-large, tubular white flowers, streaked in purple and spotted in green.  

Gentiana algida -- perhaps I should call it 'farewell to summer' 
(Photo Yvette Henson)

Wednesday, October 5, 2022

Get Ready to Sow Some Seeds!

 Posted by: Deryn Davidson, Horticulture Agent, Boulder County

Photo from CSU Extension Fact Sheet 7.233

Native wildflower and grass seeds can be sown any time of year, but we are entering the ideal sowing window: Fall. Whether you are looking to covert a small section of your yard to a more naturalized looking pollinator garden, or your HOA is considering creating large areas of native vegetation, as the cooler weather approaches, you can be planning out your steps.

Seed sourcing: There are many wildflower mixes available both in retail and online spaces. Buyers beware, some of the species that might be included in those mixes are often non-native and invasive. They can quickly become more of an issue than a benefit. Be sure to look closely at the species list and try to source your seeds from local, reputable sources rather than more generic, national level brands. What might work well in the one part of the county, could be a problem here in the intermountain-west. Which wildflower mix you choose will depend on your location and site. Just like if you’re planting live plants from the nursery, you want to make sure that you choose appropriate species for your soil type, exposure (sun vs. shade), elevation, and moisture levels (what you’re willing to provide or based on site conditions).

Site preparation: Site preparation is typically necessary to get the space ready for seeding. In some areas   this is minimal, in other areas you made need a full year. If you’re removing turf, that needs to be done ahead of time. If you have an open area of soil, weed control needs to be done before sowing so that next spring the seedlings don’t have to compete with established weeds. If your soil is compacted or low quality, you’ll want to add organic matter into the top 6-inches to make the seed bed more hospitable. If you till it in, you will bring weed seeds to the surface. While this sounds like a bad thing, you can use it to your advantage. If you start prepping soon enough in the season, you can water the area and allow those seeds to germinate. Then you can come in and weed those out. Preparations may take more time in areas where the number of weed seeds is high or if you have more difficult to remove species like Canada thistle or bindweed.

Seeding: Fall is a great time to seed most species that will come in a native wildflower seed mix. Ensuring good “seed to soil” contact is important. By that we mean making sure that each seed is touching the soil and typically has a thin layer over it. You can accomplish this by putting your seed out at the proper rate and then lightly raking over it. Then tamp the soil with your feet by gently walking on it to make sure that contact is happening. Purchased seed should come with a recommended “seeding rate”, or the number of seeds to sow per area of ground. For example, the recommendation might be 5-pounds per acre if you’re doing a large area, or 1-ounce per 100-square feet for smaller areas. If you’re seeding larger areas, the rake and tamping by walking method might not be realistic. In those instances, you’ll want to investigate mechanical seed spreaders and larger options for achieving the seed to soil contact like a sod roller. The moisture that we (hopefully) receive over the coming winter months will allow for germination the following spring. If we don’t get much moisture over the winter, be sure to water the area in the spring and keep it moist (not soggy wet) until you start to see seedlings emerge.

For more information including a plant list, check out Fact Sheet No. 7.233

Tuesday, October 4, 2022

Can't Afford a Tropical Vacation? Buy some Tropical Plants Instead!


As the days start getting shorter and the nights colder, we slowly begin to tuck our gardens away for the winter. Although it might feel like the first shoots of spring can’t emerge soon enough, thankfully we can still entertain our green thumbs in the meantime. How, you ask? With houseplants, of course!

Many of our common houseplants are tropical or subtropical plants, meaning that they can’t withstand our colder or freezing nighttime temperatures. With that in mind, they can actually be used as annuals in our gardens during the summer. However, more often than not, they’re found keeping cozy in our homes year-round, which is especially great for those of us, like me, who live in apartments and don’t have much outdoor space for plants!

Houseplants have a wide range of light and water requirements, maintenance needs, and looks, so I can assure you that there’s a houseplant for (almost) every situation, space, and person. Let’s take a look at three of the most popular houseplants, which are all great low-maintenance options for beginners and experts, alike!


‘Golden Pothos’ after a recent “haircut”. In lower light, the ‘Golden Pothos’ will have less of the yellow variegation.

First up is the pothos (Epipremmum aureum), a tropical evergreen climber that originates from Southeast Asia to the western Pacific. When not forming a ground cover, this plant can typically be found climbing trees by sending out aerial roots that latch onto the tree trunk. Due to its location in the canopy, the pothos is accustomed to shadier conditions and, thus, can do well in the lower-light areas of your home. Make sure to keep your pothos in well-draining soil and allow the soil to dry out between waterings to avoid root rot. Mine generally like to be watered every two weeks or so – you can always tell if your pothos needs to be watered when the leaves begin to wilt a little.

Swiss cheese plant; older leaves often have more fenestrations than do younger leaves. 

The Swiss cheese plant (Monstera adansonii) is another favorite, particularly due to the fenestrations (or holes) that develop in the leaves over time. This plant comes from Central/South America and, similarly to the pothos, climbs up the canopy using aerial roots. On account of their similar growth habits, the Swiss cheese plant has the same environmental/cultural preferences as does the pothos. They can also both be easily propagated by taking cuttings of the plant and placing them in water! After several weeks, your cuttings will establish new roots and can be potted with well-draining soil. While you can propagate your plants anytime (I always have at least a few cuttings sitting on my “propagation shelf”), it may take longer for the cuttings to root in winter or you may consider using an additional light source.

A Swiss cheese plant cutting has taken root in water. 

Freshly potted ‘Golden Pothos’ cuttings that had established strong root systems in water.

Spider plant ‘Variegatum’. 

Finally, we have the spider plant (Chlorophytum comosum), which comes to us from the coastal areas of South Africa. Spider plants form clumps of thick rhizomes to store water, so they can tolerate limited/inconsistent watering and like for the soil to dry out between waterings. Unlike the pothos and Swiss cheese plant, the spider plant prefers medium to bright light, consistent with its native habitat. Spider plants can be easily propagated, but it is done differently than the latter two plants. On one hand, you can simply divide a spider plant and its rhizomes to create multiple plants. More popularly, spider plants will produce long stems (under the appropriate conditions) with plantlets (or baby spider plants) at their ends. If you wait long enough, the plantlets will produce roots while still on the stem and, at that point, can be clipped from the stem and potted.

 Spider plant ‘Vittatum’ with plantlets growing from stems. The roots of the plantlets have not yet established.       

So, without further ado, ditch the tropical vacation and go buy some houseplants instead (or better yet, do both)! While houseplants are lovely to look at, fun to maintain/propagate, and can help filter the air in your home, they can be toxic to children and pets so take caution when selecting houseplants.  What's your favorite houseplant? Let us know below!


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