CO-Horts Blog

Sunday, March 30, 2014

Arbor Day is Coming: Tree Planting 101

Posted by: Alison O'Connor, Larimer County Extension

My body hurts. Carol was right. I spent the day in the garden, doing my spring clean-up and towards the end of the day, I thought to myself, "Well, I might as well plant that linden."  You might remember my previous linden, the one that was a hot mess--sunscald, girdling roots, planted too deeply. Through an act of utmost generosity, Dr. Klett donated a linden to me to replace the one that met its fateful demise. I'm bound and determined to make sure my new linden has a healthy and long life. Just like all the trees you may plant this spring for Arbor Day.

So how do you plant a tree? Well, it really is more than digging a hole. If you're a Master Gardener, you've probably sat through my 3-hour lecture on tree planting, but here's an overview (with pictures!) to help you plant your tree correctly for long-term success.

Before you even THINK about planting, make sure to call 811 to have your utilities located. This is very, very important, especially since March Madness is occurring and cutting your neighbor's cable line will be bad news.

First of all, my tree had some structural defects, so I did some pruning to remove broken branches, those that were rubbing and picked a new central leader. In most cases, you should not have to do this. Your tree should come properly pruned from the nursery. With this tree, the need for pruning had been overlooked for a couple seasons.  I removed quite a bit of branches, but for me, it's easier to prune prior to planting to correct these problems than wait until they are a major issue.

I knew the site I wanted to plant my tree in (the same place as the old linden) and the first step was to determine how deep my hole needed to be and also how wide my hole needed to be. So I measured the height of the root ball and also the width of the root ball. The hole should be about three times as wide as the root ball, so just multiply by three. The depth of the hole needs to be 1-2" shallower than the root ball. Yes, the tree will sit 1-2" above the soil grade (trust me on this). The reason for this is because we want the structural roots to be right at grade (not too deep or too shallow).  Roots need oxygen to function, and in our clay soils, the deeper you go, the less soil oxygen is available (due to small pore space). So make sure your tree sits above grade.

You should also check to make sure that the structural roots (the big 'uns) are only 1-2" deep within the root ball. Use a thin screwdriver to check. You'll know you've hit a structural root because your screwdriver will meet a solid point of contact.  In my case, this linden was planted properly and the structural roots are 1.5" down in the root ball, so when I plant this tree, the roots will be at grade when I finish.

Now that you've determined your depth and size of the hole, start digging. And digging. And digging. The root ball on this tree was enormous and the hole was nearly 6 feet wide, tip-to-tip. The hole should be saucer-shaped and more shallow than deep (the hole width is key to rapid root regeneration). Make sure you check your hole depth from time to time, to ensure that you don't dig too deeply. Lay something flat across the hole and measure the depth. The soil at the bottom of the hole should be firm--stamp on it with your foot. If you leave the soil fluffy and loose, the tree can sink as gravity takes over and you water.  Again, the tree needs to sit on firmed/un-dug soil.

Remove the tree from its container. Wiggle off the container...or cut it off if it's being stubborn. If you're planting a balled-and-burlapped tree, leave the wrappings on the root ball until you get it into the hole--you don't want to risk the root ball shattering and potentially damaging the root system.

And what do we see after removing the container? Jeepers creepers, a mess of circling roots on the outer periphery of the root ball!
The old recommendation was to take something sharp and slice through the roots. Unfortunately, research proved that this was ineffective (check out Jeff Gillman's blog on the subject; also see Ed Gilman's work). The new recommendation is to shave off about 1 inch of the outer periphery of the root system to physically remove the circling roots. Let me get my saw...

So I shaved the root system (bottom too). I know, it seems...wrong. But truly, in the long run, it's going to be better for the tree. Be ruthless. The thing with circling roots is that those little roots will get bigger. They can turn into girdling roots, which can affect the tree's health. In fact, there's a thought that many tree failures are now a result of girdling roots, which act like a boa constrictor on the trunk, cutting off water and nutrient transport. Plus, circling roots (the existing ones) will not grow laterally into the site soil. After shaving, I had a pile of roots:

Now that I've shaved the root ball, the tree is ready to plant. Heave ho into the hole! Check it from several angles and make sure it's nice and straight. Also make sure the root ball is sitting 1-2" above grade.

Once you're satisfied, add a shallow ring of firmed soil at the base of the root ball. Doing this will eliminate the need to stake in most cases. Yes, it's true! The shallow ring of soil is going to keep the tree in the ground and prevent it from rocking back and forth.

Staking can actually damage the tree. There are really only three reasons to stake following planting: windy sites, near people activities or for a tree that cannot support its own weight. For the most part, a tree in a homeowner's yard should not need to be staked.

Then add your backfill. I always get the question about amending backfill soil, and really, science has proven that it's not beneficial long term. The rule of thumb with organic matter is to have 5% in your soil. Adding a "rich compost" to the backfill is essentially planting your tree in a container. Plus, too much organic matter can be detrimental. It can hold too much water and decomposes more rapidly. So I'm not an advocate of adding copious amounts of organic matter to the backfill, unless you have a really awful soil. It's more important to plant the tree correctly than to rely on organic matter to make things better. You'd be surprised at how successful roots are at growing into site soils.

When you're backfilling, do not put any soil on top of the root ball. If you do, there's a good chance that when you water, the water will skirt around the root ball. Water is lazy. It's going to take the path of least resistance, which means it doesn't want to go through soil texture interfaces, like the one with the root ball (dark, rich soil) and the native site soil. Keep the soil off the top of the root ball.

After adding the backfill, water gently to allow the soil to settle. Then add more backfill, water and repeat as necessary. You may have to do this several times to get the tree to final grade.

Finally, add organic mulch. It helps keep weeds down, stabilizes soil moisture and also adds organic matter as it breaks down. Just like the backfill, keep all mulch off the top of the root ball. The mulch should come up to the edges of the root ball, but not cover the top. Mulch on the top of the root ball will not decrease moisture requirements, but it can increase circling roots. When you're finished, you should clearly see the root ball, which makes it easy to water, since you can focus your efforts for the first season on just watering the root ball. After a season or two, start watering the planting hole and beyond. The rule of thumb is to apply 1-2 gallons of water per inch trunk diameter as needed (don't let things dry out), maybe 3-4 days/week, depending on the temperature and wind.

And you're done! Congratulations! The CSU Garden Notes also have a great publication on Tree Planting Steps. Don't worry....I will remove the tree wrap by mid-April.

Wednesday, March 26, 2014

Sixty Second Secrets for Gardeing Success: Lawnmower Maintenance

Today on Sixty-Second Secrets for Gardening Success: Lawnmower maintenance!

To keep your mower in tip-top running condition, have a competent service professional thoroughly inspect your mower at least once a year.

Some things to ask them to do for you include:
·       Sharpening and balancing the blade. A dull blade tears grass and can leave in prone to disease, and an unbalanced blade can cause your mower excess wear and tear.
·       Check the air filter. If you are using the mower in dry or dusty conditions, you will need to replace the air filter more often.
·       Check the spark plug. Always ensure that the spark plug is clean and gapped correctly.
·       Check the carburetor and have it adjusted if necessary.
·       Check the oil, and have it changed if needed.
·       Check the wheels, bags, and belts and replace as needed.

By keeping your mower in proper working order, you can help maintain a healthy environment, pocketbook and lawn.

For more information on lawn care, contact your local
CSU Extension Office.

Sixty-Second Secrets for Gardening Success is a production of
Colorado State University Extension.
CSU Extension: Extending knowledge, changing lives.

Sunday, March 23, 2014

PLANET Student Career Days at CSU

Posted by: Alison O'Connor

The Colorado State University Department of Horticulture and Landscape Architecture just hosted the "horticulture Olympics" on the CSU campus during spring break. Over 60 schools, from all across North America, descended upon Fort Collins to compete in 28 events as part of PLANET. These events included: irrigation design and troubleshooting, plant and weed identification, tree climbing, landscape estimating, equipment driving, landscape installation, personnel management and many more. Simply put, it was pure and utter chaos for three days, and a lot of fun.

Brigham Young University-Provo took home first place, but our own CSU Rams placed 7th, and the 23 students who made up Team CSU are to be congratulated. The HLA faculty involved all deserve credit, especially Zach Johnson, who was acknowledged as the PLANET Educator of the Year. The dozens of volunteers, including many Master Gardeners, helped make this event a success.

The landscape installation event was the pinnacle of the competition, where each school had a set plan and three students install the design to scale in just under two hours. All teams had the same materials--shrubs, trees, mulch, groundcovers and sod. They were graded on time, accuracy, safety, neatness and aesthetics. See pictures below. Although it was snowy and very cold, the students' enthusiasm was heartwarming and it was fun to hear all the school fight songs.

Congratulations, CSU students!  We'll cheer you on in North Carolina next year.

Wednesday, March 19, 2014

Sixty Second Secrets for Gardening Success: Pruning Roses

Today on Sixty-Second Secrets for Gardening Success: Pruning Roses!
Winter frosts and freezes are damaging to roses so it’s best to wait till early spring to prune roses.
Pruning roses is easy and will make a big difference in the plants health so it’s best to prune every spring.

Start with a
sharp pair of bypass pruners and a good pair of gloves.

Next remove any
dead, diseased, or damaged canes. Canes should be pruned at a 45 degree angle about ¼ inch below the point where you see green or healthy wood.
After you have removed any dead, diseased, or damaged canes you can focus on the shape. Prune your rose ¼ inch above an outward facing bud. This will help the plant grow in way that will prevent branches from growing through the plant, allow for more air and light penetration into the plant, and reduce the possibility of disease.
For more information on roses, contact your local CSU Extension Office.
Sixty-Second Secrets for Gardening Success is a production of Colorado State University Extension.
CSU Extension: Extending knowledge, changing lives.

Sunday, March 16, 2014

Why Trees Are Frickin’ Awesome

Alexis Alvey, Horticulture Agent, CSU Denver Extension

I have always loved trees and I’m sure that many of you gardeners out there feel the same why.  I have always been enchanted by the beauty and power that they convey, their leafy greenness and tall trunks reaching up towards the sky.  I could go on, but I won’t since I know that I’m preaching to the choir.  Shockingly, there are some folks out there who don’t feel the same way and who don’t like trees (insert audible gasp here)!  Perhaps with a little more convincing, we can get more people to understand the need for trees so that our city officials can make the correct decisions about our urban forest.  So here are some awesome and quantifiable benefits of having trees in our cities:

  •         According to a study by the US Forest Service that evaluated the benefits of community trees, for every dollar that a city invests in a community tree program, trees will give back $1 - $2 in environmental benefits.
  •         Shaded streets are 10-40 degrees Fahrenheit cooler since paved areas store about half the sun’s energy.  Tree evapotranspiration accounts for an important percent of this cooling effect. 
  •         A well-placed tree can reduce home cooling costs by 10-30%.  In summer, trees block 70-90% of the sun’s radiation on a sunny day.  Plant trees so that they can shade air-conditioning units and west-facing walls.
  •         Trees improve air quality by removing ozone, particulate matter, nitrogen dioxide, sulfur dioxide, and carbon monoxide.  The Forest Service’s UFORE model estimates 1200 – 1800 tons of atmospheric contaminants are removed annually in a major city in thee US by their urban forest.
  •       One tree can absorb the same amount of carbon in a year that a car produces while driving 26,000 miles.
  •         A large percentage of paved surfaces in cities can contribute to flash flooding in storm events.  By intercepting precipitation, trees reduce the speed and quantity of raindrops hitting the ground.  One study found that in a city with a tree canopy cover of 22%, runoff was reduced by 7% by those trees.  There is also a reduced cost in constructing stormwater retention ponds.

So that’s quite a lot of environmental benefits that trees provide!  But did you know that trees also provide psychological and social benefits as well?  Nature has a restorative and calming effect on human beings.  (If you want to look deeper into this subject, take a gander at Richard Louv’s book, Last Child in the Woods.)   Some social benefits of trees include:

  •         A landmark study conducted in the mid ‘80s found that hospital patients recovering from abdominal surgery who had a view of a wooded scene vs a brick wall out their windows recovered more quickly, required less pain medication, and had fewer complications.  Postoperative hospitalization was reduced by 8.5%.
  •         A study in 2001 found fewer violent and property crimes occurred in areas of dense trees and grass.  The authors concluded that plants may mitigate the psychological precursors to crime, such as irritability, inattentiveness, and impulsive behavior.  Landscape plants may increase the perception of safety of inner-city residents by providing an open and inviting place to congregate.
  •         A study in Massachusetts found that trees added 5-15% to the sale price of hypothetical homes on lots with and without trees.
  •         The US Forest Service reports that consumers spend 12% more for goods and services in tree-lined business districts.  Visitors also tend to shop more frequently, stay longer, and spend more for parking.

Trees are really great with all their environmental, psychological, and social benefits!  If you want to find out how much in benefits your tree is providing, check out the National Tree Benefit Calculator at  For instance, the calculator estimates that a 14 inch Kentucky Coffee Tree gives back $100 per year in benefits.  Pretty frickin’ awesome!!!

Thursday, March 13, 2014

Fungus gnats

By Irene Shonle, Gilpin Extension

As I was reading in bed the other day, a tiny black insect kept buzzing around my ears and trying to fly up my nose until I finally became fed up and dispatched it.   Darn those fungus gnats!  They seem to be having spring population boom right now.  Judging from the number of people who have been calling me or commenting on the situation at their house, I’m not alone.   The only thing I can say in their favor is that the flying adults don’t bite, so their annoying qualities only extend to the fact that they like to invade your personal space (and that they mate and give rise to the larvae – that is the life stage that can cause problems).

The first step in figuring out how to solve the issue is to properly diagnose it.  It can be hard to tell the difference between fruit flies and fungus gnats, but since they usually come from different sources (unless you’re worm composting), it’s important to sort this out.  First, note the season. In summer, fruit flies are much more common, but in winter, the fungus gnats usually rule supreme. Fruit flies are relatively large and stocky, with large (often bright red) eyes and a light brown body.  Fungus gnats, in contrast, are smaller and more delicate, resembling a tiny mosquito, and are black.   See the photo below for a photo with both species.
Fungus gnat (left of middle pair) next to fruit fly on a yellow sticky trap

Adult fruit flies hatch from eggs laid in overripe fruit or other fermenting produce, whereas fungus gnats mostly hatch from eggs laid in houseplant growing media.  If you are mostly seeing the critters in bedrooms and areas where there are plants, they are almost certainly fungus gnats. (Go here for more on fruit flies and other household flies)

While the adult fungus gnats are annoying, the larvae are minor to major pests on houseplants. They primarily feed on fungi, algae and decaying plant matter but they will also feed on plant roots.  In high enough numbers, the larvae can stunt the growth of the plants.

Here’s how to deal with them:
First, let plants dry out between watering (just before the point of wilt).  Fungus gnats are very attracted to moist media, and the larvae only live in the top 2-3 inches of soil. Reducing watering reduces the survival of the eggs and larvae.  In the cooler, shorter days of winter, it is especially easy to overwater plants, but most plants will actually be happier and healthier when not overwatered.

Second, repot your plant with fresh growing medium – as it breaks down, the potting soil tends to hold more moisture, which promotes fungus gnat development.  As a bonus, your plant will probably perk up, too

Third, put up some yellow sticky traps around your plants to trap the adults.  Reducing the adult population will reduce the numbers of eggs laid, and can break the cycle.

Finally, if you’re still going crazy, try insecticides. Often, a Bt (Bacillus thuringensis) soil drench will suffice to kill the larvae, but is non-toxic to humans.  Otherwise, you may need to use pyrethroid-based insecticides, with extended persistence for use on houseplants (containing the following active ingredients: bifenthrin, cyfluthrin, permethrin, and lambdacyhalothrin).  Short-persisting contact insecticides such as those containing pyrethrins, soaps, oils, and neem, do not provide sufficient long-term control of fungus gnat adults and require repeat applications at short intervals (couple of days) to exhibit effects.

For more information, go to the following fact sheet:

Wednesday, March 12, 2014

Sixty Second Secrets for Gardening Success: Shamrocks!

Today on Sixty-Second Secrets for Gardening Success: Shamrocks!

Shamrocks represent good luck and are a popular house plant, especially during Saint Patrick’s Day.

Shamrocks are easy to grow if you follow these five simple and easy to remember steps:

·       Shamrocks prefer direct sunlight, be sure to place your shamrock in a window where it will receive plenty of light. Shamrocks will flower, even during winter, if they receive enough light.

·       Shamrocks like food! Fertilize them regularly with either a liquid houseplant or time release fertilizer during their growing season.

·       Houseplants prefer moist soil. Avoid allowing your shamrock to dry out during the growing season.

·       During the growing season, give your shamrock a growing temperature between 50 and 70 °F.

·       Shamrocks have a dormant period. When your shamrock goes dormant, don’t fret! Just place it in a cool, dry location out of direct sunlight.

For more information on houseplants, contact your local
CSU Extension Office.

Sixty-Second Secrets for Gardening Success is a production of
Colorado State University Extension.
CSU Extension: Extending knowledge, changing lives.

Tuesday, March 11, 2014

Spiders gotcha crawlin’?

Kurt Jones, CSU Extension, Chaffee County

Most spiders are regarded as beneficial and should not be destroyed. Many people fear spiders because of stories or myths about them. Others object to spiders because of their habit of building webs in and around the home.

Spiders differ from insects in that they have eight legs rather than six and only two body regions instead of three. Some spiders spin a web while others do not.

Indoors, many spiders may be found in basements, crawl spaces and other areas where it is somewhat damp. Other spiders, however, prefer a drier situation and can be found in the upper corners of rooms, in attics or in floor vents.

Life Cycle

After mating, female spiders lay eggs in clusters called egg sacs. A few species lay their eggs in dark hiding areas and not in a silken sac.

Some female spiders guard their egg sacs; others carry the sacs with them. A female may          produce several egg sacs in her life. Eggs usually hatch into small spiders within three weeks.  Mating and egg laying can occur at any time of the year, depending upon species.

Are Spiders Dangerous?

Two species of spiders found in Colorado can be harmful to humans if they are bit.  The black widow spider and the brown recluse spider have poisonous bites. These two spiders are not aggressive and bites are uncommon. Their bites are rarely fatal but can cause serious illness.  Medical attention should be sought in the case of bites from these spiders.

Black Widow Spider

The black widow spider, Latrodectus hesperus, is common throughout Colorado. This spider can be found in undergrowth, under stones, in the openings to rodent burrows, in hollow trees or in any other kind of protected area. Around the home it may be found in garages, window wells, crawl spaces and occasionally in basements. It likes undisturbed areas in and behind objects.  Homes in new developments will be bothered for some time from natural populations in the area.

The female black widow is poisonous, while the male is not. The female is about 1 1/2 inches long. The body, excluding the legs, is about 1/2 inch, jet black or dark brown, and usually has red markings that can take the shape of an hourglass on the underside of the abdomen. The male is smaller with brown markings. The two sexes may be easily distinguished by their sizes and by the pattern of the red marks on the abdomen.

Brown Recluse Spider

The brown recluse spider, Loxosceles reclusa, is rare in Colorado. There are a number of other possible causes for symptoms similar to a bite from a brown recluse spider. In Colorado, these should be considered more likely than a brown recluse bite, given its rarity in our state. Specimens have been found and positively identified in the southeastern portion of the state. Brown recluse spiders occasionally have been brought into other parts of Colorado with household effects being moved in from other states where this spider is common. The brown recluse can live both indoors and outdoors, but in cooler climates it prefers to live in houses. It usually is found in bathrooms, bedrooms, closets, garages, basements and cellars.

The brown recluse spider is about 1/2 inch long, usually tan or buckskin, with long, dark brown legs and a violin-shaped dark mark immediately behind the eyes. The base of the violin mark is on the head with the violin neck pointing toward the abdomen. The brown recluse spider is the only spider with three pairs of eyes; all others have four pairs. It produces little webbing since it hunts its food.