CO-Horts Blog

Friday, September 29, 2017

The Orchid: a delicate impossibility or a manageable houseplant?

By Amy Lentz, Weld County Extension

Contrary to what you may have heard, orchids are not difficult to grow and in most cases, they will grow in the same conditions as your other houseplants and require a similar amount of care. With the proper amount of light, water, humidity, temperature and fertilizer, orchids can thrive! Some types of orchids such as Phalaenopsis or Cattleya types can be easier to care for than others and make great options for beginners. 

Healthy roots are essential to the growth and health of your orchid so the choice of growing medium plays an important role. Many orchids naturally grow in trees in the wild and these types of growing mixes mimic that natural setting.  These types of orchids prefer a very porous growing medium made of materials such as bark, husks, perlite, or clay pebbles, all of which are ideal for the roots to establish themselves and receive adequate air movement.  

Due to the very porous nature of orchid growing mixes, water will readily flow through. You will want to water your plants thoroughly to soak the roots and growing medium. Never let your orchids sit in standing water because their roots need oxygen, too. One way to accomplish a good watering is to place the plant in a sink or tub, water it,enough to wet the medium, wait a few minutes, water it again, and repeat this until the medium is well soaked. Make sure to drain off any excess. 

Orchids like to dry between watering so don’t water too frequently. If you are unsure whether you should water again, wait a day. You can also get a feel for how heavy the container is after watering and if it is lighter than usual then give it a good drink!  While your orchids are actively growing, fertilize them with a houseplant or orchid formulation at a diluted rate (50%) once a month.

Orchids prefer some humidity and one way to increase the humidity level is to grow your plants in groups or place a dish of water nearby to produce humidity as the water evaporates. You can also mist them but be careful not to keep them moist for prolonged periods of time. I’ve managed to cheat by growing mine near the kitchen sink and dishwasher.

Sunburn symptoms on orchid leaves can be light to dark brown and
will dry up the plant's leaf tissue. It will not spread once the plant is
removed from direct light. Avoid placing orchids in direct sunlight.
Colorado gets over 300 days of sunshine per year which is great for our window-bound houseplants and especially orchids. However, with the high intensity of the sun you will need to place your orchid in indirect sunlight to make sure they do not get sunburned. A south or west facing window may be too intense, so placing your orchid about 2 feet away from an east facing window is ideal. If your orchid is hesitating to flower, then you can encourage it by relocating it to an area with higher light levels. 

Room temperature is ideal so you won’t need to make any adjustments for your orchids. They prefer temperatures between 55 and 75 °F, so 65 to 70 °F is perfect. Phalaenopsis types can do well in temperatures up to 80 °F.

Orchid blooms are interesting, delicate and stunning! They can last for several weeks or even months if the plant is happy and are a great addition to you houseplant collection.

Learn more about Phalaenopsis and Cattleya orchids here:

Monday, September 25, 2017

The Unseen Benefit of Native Grass

The Unseen Benefit of Native Grass
By Linda Langelo, CSU Horticulture Program Associate
 There is more to grass than just mowing, weed prevention, fertilizing and aerating.  Grass, both hybridized and native grass, plays a very important role in the world not frequently on the minds of grass lovers.  Panicum virgatum, Switchgrass with a deep root system traps coarse sediment and plant nutrients from farm fields.  Yes, that's right, root systems do this.  The unseen part of the grass not only supports the grass's health, but also helps our landscapes filter water.  The larger the area of grass in the landscape, the more opportunity to better filter the water over time especially with types of grasses with deep root systems.  These would be primarily native grasses.
According to Ronald R. Schnabel in his article, Improving Water Quality Using Native Grasses, "Native grasses improve water quality, both in limiting the source of pollutants and intercepting pollutants before they enter a water body."  Native grasses are more than just about conserving water usage, reducing herbicides and fertilizers. 
In fact, native grasses and plants have deeper root systems that can go several feet into the ground. A grass's genetic make-up and environment factors play a role in root depth.  In general, the grass with more top growth also produces a significant amount of root growth to support the top growth.  Big Bluestem, Andropogon gerardi, grows a root system spreading nine feet in the ground.  With roots to this type of depth, we do not usually think about cleaning the water, but rather soil stabilization and a decrease in floodwater.
Buffalo grass used more frequently in home landscapes has a root system that reaches to a depth of eight feet.  The deeper the root system, especially in clay soils, the more water is absorbed and retained in the soil. With the more popular turf grass, Kentucky Blue, the roots reach six to eight inches in depth.
Here is a short list of other native grasses that help with improving water quality and can be added to enhance the natural beauty of the landscape:
Andropogon scoparium   - Little Bluestem
Bouteloua curtipendula   - Side Oats Gramma
Sorghastrum nutans         - Indiangrass
Sporobolus heterolepsis   - Prairie Dropseed
Panicum virgatum            - Switchgrass
Some of these native grasses are very attractive. Most cultivated varieties appear in cultivation.  Some have cultivated varieties have been crossed within the same Genus and now in a hybridized form bears a particular attractive feature that breeders produce. Some are found naturally in the wild and just brought into cultivation. Some are found in seed batches of other cultivated varieties and are called genetic mutations that change the appearance of the plant in some way.  According to Moon Nursery, Dr. Hans Simon spotted Panicum virgatum 'Shenandoah' in a batch of seedlings of Panicum virgatum 'Hanse Hermes'. This seed was an attractive mutation.  It was chosen for its short compact habit and improved red color.  Simon named the plant for Virginia’s Shenandoah Valley as a tribute to the species’ country of origin.  Here are some other cultivated varieties you may be familiar with of Panicum virgatum  listed below.  Many of these cultivated varieties of Switchgrass have been in the trade for over 15 to 20 years.  
1) Cloud Nine - 5 to 6 feet
2) North Wind - 5 to 6 feet
3) Dallas Blues -6 to 8 feet
4) Heavy Metal -2 to 3 feet
5) Shenandoah  -2 to 3 feet
Take a look below at pictures of the native grasses listed above and judge for yourself the merit they might have for a place in your landscape.

Photo credit: Sporobolus heterolepsis

Photo credit: L&H Seeds, Indian Rice Grass

Photo credit: Tri Valley, Side Oats Gamma

Photo credit: North Creek Nurseries, Little Bluestem


Photo credit: North Creek Nurseries, Switchgrass

So I hope you look at native grasses differently.  I also must add that grass also produces oxygen.  That goes for all grasses.  There are plenty of native plants that can enhance your native grasses creating beautifully landscaped properties that are sustainable environments. 

This is an early plug for a 2018 conference - Landscaping with Colorado Native Plants, February 10, 2018 at the Denver Botanic Gardens.  Click on the following link for more information: .  

Native plants in general have some wonderful qualities.  Please keep this workshop in mind.  

Wednesday, September 20, 2017

Planting Perennials in the Fall

By Sherie Caffey, Horticulture Coordinator, CSU Extension-Pueblo County

Newly transplanted Apache Plume
    Don’t put those shovels and gardening gloves away just yet! There is still a little time left to plant perennials in your landscape.

    When you think of planting new plants, Spring definitely comes to mind. Fall, however, can be a good time to plant as well, and many garden centers will be having end of season sales at this time, so you can score some great deals! As long as the plants have time to establish good roots before the first killing frost comes, they should be able to survive the cold season. Down here in Southern Colorado, we won’t expect our first frost until mid to late October, so there is still time.

    If you are going to do some fall planting, don’t forget the mulch! Fall planted perennials are more susceptible to frost heaving in the soil due to their smaller root systems. Mulching your new plants will stabilize the soil temperature, minimizing the effects of heaving. The mulch will also prevent fluctuations in soil moisture, which will make your new plants happy as well.

    When you dig the hole for your perennials, make sure it is wide enough, you want there to be plenty of room for the roots to spread out and grow. You can amend the bottom of the planting hole with some good fluffy garden soil. Be sure to mix the soil in with the native soil to prevent an interface issue. To give your plant’s roots a boost, you can also add some root stimulator, or beneficial mycorrhizae to the bottom of the hole.
Loosened root ball

Bound root ball
    To give those roots a fighting chance, be sure to break up the root ball a bit. Roots can become bound in pots and will have trouble spreading out in the soil. You can score the root ball with a knife or the plant marker in a few places to loosen the roots. I prefer to gently dig my fingers into the root ball until it looks loose and messy. Remember, good strong roots will lead to a good strong plant, so do everything you can to make sure they have a good start.

    Even if you are planting xeric plants, they will need to be watered when they are young. After planting, give the plant one good round of water, wait 5 or ten minutes, and give it another. This will ensure that the water is soaking all the way down to where the roots need it most. Depending on conditions, the plants will need to be watered every so often until the roots become established. You should also water throughout the fall and winter when there is a warm spell and has not been precipitation in a few weeks.
Fall transplanted perennials

    I hope you are inspired to some last minute planting before the cold season begins. Happy Fall and happy planting!

Monday, September 18, 2017

Tomato Uh-oh!

Posted by Mary Small, State Master Gardener Coordinator
No, this isn’t a new game – the title comes from something my kids would say when they were little. It usually meant that something (usually not good) just happened.

Our tomatoes had some uh-ohs this season that produced (in addition to delicious fruit!) lively discussion and internet searches for information. We grew a few hybrid varieties and one heirloom that produces beefsteak tomatoes. Of course, I failed to write down the name and the writing on the tag has faded. I think it might be Black Krim, though. It was the variety with the most interesting symptoms.
Catfacing (Forestry
  Catfacing – this is a cute name for distorted fruit that results from abnormal development of female flower parts. It can be caused by low temperatures during flowering (below 58 degrees F) and 2,4-D. In addition, beefsteak and some heirloom types are genetically more susceptible. At the front end of the season and now late in the season, cool temps at flowering certainly could have happened. But the only cause for this in mid- summer that makes sense is the cultivar and type of fruit.


Zippering –This one is caused by the male flower parts (anthers) sticking to the developing fruit. Cool weather during fruit set and genetics can play a role.

 Concentric growth cracks – this happens when the insides of the tomato grow faster than the skin. The skin can’t keep up with the interior tissue expansion so it cracks or splits. It can be caused by extreme fluctuations in water and temperature as well as genetic susceptibility. Any of these three causes could have figured in this season – but only the heirloom has the problem. 
Concentric growth cracks

Green or yellow shoulder
Green (or yellow) shoulder – the tomato "shoulders" (the stem end of the fruit) stay green or yellow and hard. Adverse tomato growing weather, soil nutrition and genetics (again!) are possible causes – but the exact reason hasn’t been determined.  Only one hybrid variety had this symptom.

Psyllid nymphs

  Psyllids –These were thankfully NIMG – not in my garden - although I have dealt with them other years. The insects feed on sap and inject toxic saliva into the plant. This stops growth, stunts leaves and causes them to turn yellow and/or purple. Tomato fruit is abundant – but tasteless. The little stinkers aren’t easy to find until you a) check the undersides of leaves for the nymphs or b) find what looks like sugar or salt accumulating on leaves, stems or the soil underneath plants. While there are insecticides available– and sulfur works well – it may be too late depending on when you discover the problem.

This has been one of the most entertaining, educational and delicious tomato years we’ve had in a long time. Can’t wait for next years’ adventures!

Friday, September 15, 2017

2017 ‘Best Of’s’ from Colorado State University Annual Flower Trials

Posted by Dr. Jim Klett, Professor and Extension Landscape Horticulturist, Colorado State University.

In the 2017 Annual Flower Trials we had over 850 different varieties entered from 22 participating companies. Initial evaluations were held on August 1, 2017 with close to 150 industry and advanced master gardeners participating. The second evaluation was held on September 8, 2017 with the Trial Garden Advisory Committee. It was a difficult task to come up with our “Best of Show in the Garden” for 2017 along with best new variety and best novelty plants. The winners include:

Best of Show: Calibrachoa CHAMELEON® Indian Summer Improved from Westhoff
The eye catching varying shades of red, rose, pink and yellow flowers on vigorous plants with exceptional flower power resulted in this Calibrachoa being granted the Top Honor in the 2017 trials. The flower of the CHAMELEON® series are selected for their ability to change color as environmental conditions change, which is evident with this selection. Plants maintained a uniform growth habit that enveloped the containers as a ball of flowers.

Best Novelty: Millet ‘Copper Prince’ from Pan American Seed
This plant is a great selection for the series and textures in a garden. The stout, large, fuzzy dark rose/bronze panicles rise high above the plant. The foliage has wide blocks with a uniform caramel/ copper color throughout the summer. This plant will create a very dramatic look in a landscape or large container.

Best New Variety: Lantana Luscious Royale Cosmo from Proven Winners
Plants were very uniform with a rounded habit and strong flowering all over. Flowers had a unique color and sat on top of the foliage. It is considered by some to be a new standard for the industry.

Some Other Outstanding Plants from the 2017 Trials:

Bidens ‘Blazing™ Fire’ from Danzinger-
The fiery orange, yellow and red flowers were very prolific and spectacular. The dense mounding habit enveloped the containers as a ball of flowers. Flowers opened up darker and faded to a nice yellow.

Calendula ‘Lady Godiva™ Orange’ form Proven Winners
New breeding has created this entry with superior heat tolerance and growth habit. The beautiful double flowers were a bright, cherry oranges with shades of apricot. Plant has great heat tolerance with flowers looking great late into August.

Dianthus ‘Rocking’™ Red from Pan American/ Keift Seed-
Rich, deep red flowers were prolific on the plants with strong stems creating an upright growth habit. The vivid flowers pop out against dark green foliage. This was a low maintenance plants that did not require deadheading to maintain a neat appearance.

Monday, September 11, 2017

Maligned plants

By Irene Shonle, Gilpin County Extension

Today, as I was trying to convince someone yet again about how goldenrod (a great late-summer native pollinator plant) is probably not to blame for their fall allergy woes, I got to thinking about other plants that get maligned, either by mistaken ID or by mistaken causation.
Native goldenrod

First, let’s get back to goldenrod (Solidago spp): people are often horrified when I recommend planting it.  They look at me as though I’ve just suggested that they invite a serial killer to bunk with them.  They shake their heads vigorously, and talk about how allergic they are to goldenrod.  But here’s the thing.  Goldenrod is an insect-pollinated plant, and therefore has less pollen, and the pollen is usually a bit heavier. It has the misfortune of blooming at the same time as ragweed, a wind-pollinated plant that sends out copious amounts of pollen, and is a proven allergen. It’s just that ragweed is an inconspicuous plant, and so when people are looking around for something to blame, they see the bright blooms of goldenrod just starting to bloom, and blame it. Granted, there are a few people who have genuine goldenrod allergies, but most people (unless they’ve had it tested), are blaming the wrong plant.  Chances are, you could safely enjoy this plant in your garden.

Another plant that people often mistakenly blame for their allergies is cottonwood – specifically, the “cotton” that flies every June.  This is something that I  believed as a child – I was genuinely frightened of the cotton because I blamed it for my itchy eyes, scratchy throat and sneezing.  I even once made my family move away from a perfect campsite under a huge cottonwood with flying cotton one time to a much less desirable spot in full sun.  Sigh.  If only I had known then that there is no pollen in the cotton – just seeds.  The pollen comes much earlier in the season. However, the cotton is a very attention-getting phenomenon, and it usually occurs about the same time that many grasses are beginning to release pollen, which is usually the true allergen (for me, smooth brome was the culprit). It's possible grass pollen could collect in the cotton, which would then turn it back into a potential problem.

Another plant suggestion that receives skeptical looks is sumac (Rhus spp). People who come from the Eastern U.S. instantly think that all sumacs are poison sumacs and thereby deprive themselves of a lovely native that contributes much color to the fall garden.  While some people are very sensitive to all members of the family, including mangoes, most people have no trouble with our native species (Rhus trilobata and Rhus glabra).
Native three-lobed sumac

Finally, with the advent of social media, I get calls many times a year with people who have read about the dangers of giant hogweed, and think they have found a population and want it taken care of immediately. This is because of all the Facebook and other social media posts warning people about the dangers of Giant hogweed.  And it is indeed dangerous: Heracleum mantegazzianum is a Federally listed noxious weed. Its sap can cause severe skin and eye irritation, painful blistering, permanent scarring and blindness. People can be exposed to the sap by brushing against the bristles on the stem or breaking the stem or leaves.  The problem is that it does not occur in Colorado (at least not yet). What people are finding is our native Cow parsnip (Heracleum sphondylium), which is related and looks somewhat similar.  Cow parsnip is a native plant (not a noxious weed), and doesn’t usually produce any rashes, and many people consider it an edible plant. Just to make things confusing, though, some individual plants mah produce fouranocoumarins, which can cause phototoxicity; most of the reports seem to come from European populations. I have not heard of issues with Colorado populations, but there may be some.  For more information on hogweed and lookalikes, this page has good information:

Cow parsnip, Heracleum sphondylium, a  native plant (

 Can you think of other maligned plants?