Friday, April 24, 2015

Aeration Done Right

Posted by: Alison O'Connor, horticulture agent in Larimer County

I'm first to admit that when I give advice it's a "do as I say, not as I do" recommendation. When it comes to lawn aeration (AKA core cultivation), Extension recommends that you aerate at least once a year, twice if you can afford it. The last time I aerated was...well...a few years ago. I did it myself (with the help of burly men to help lift the machine) and it was, quite frankly, an effort!
Aeration is the best!
Last week I was driving by a park in Windsor and saw someone aerating the turf. I was impressed by how great of a job he was doing, so I stopped to chat. It turns out that Mike McFadden, of Barefoot Farms in Windsor, is passionate about doing aeration correctly. After talking for a few minutes, I hired him to aerate my under-aerated turf the following day.

What Mike probably didn't realize is that I'd be photographing him. So thanks to Mike for his willingness to be the subject of this blog.
Mike McFadden of Barefoot Farms
Why should you aerate? For many reasons, including better water infiltration to the turf root system, to combat thatch build-up, to allow for better oxygen exchange for roots and to add organic matter to your lawn and soil. And it helps alleviate soil compaction.

Steps to aerating correctly:

1. Water your lawn a couple days prior to the aeration event. In order to pull deep plugs, the lawn should have good moisture. If the lawn is too dry, the plugs pulled will be very short or the machine will simply bounce around the surface.

2. Before you start aeration, mark your sprinkler heads. I used somewhat unorthodox markers, simply because I didn't have flags. But it's very easy to hit a sprinkler head with the machine. The aeration machine generally has one speed--fast--and they aren't very easy to maneuver.
The tree stump and mini American flag mark sprinkler heads.
The design of my irrigation system is another story...
3. The goal of aeration is to "Swiss cheese" the lawn--make as many aeration holes as possible. Up, down, back and forth, horizontally, vertically, diagonally. Try to get the holes on 2" centers. If the plugs are 2-3" deep, this is also excellent. This is where commercial aeration may fall short if they only make one pass. One pass tends to result in very few holes several inches apart and quite frankly, does nothing to improve the health of your turf, except that it makes you feel good that you aerated. Following aeration, your lawn should look beat up and ugly. This will pass in time. In the long run, aeration is incredibly beneficial. (As a note, Mike made four passes on my lawn.)
A lovely little plug. Not too much thatch and 2-3" long.
4.  If you rent equipment, you have the luxury of being able to control how many passes you make. Honestly, you can't make too many holes. Ok, well if your lawn is mud following aeration, maybe you made a few too many. But really--the more holes the better!
Lots and lots and lots and lots of holes is key.
5. Leave the cores on the lawn once you're finished. If you can't stand the sight of them, then rake them up and put them in your compost pile--don't throw them away. They are full of wonderful organic matter. If you leave the cores, they will break down with a few mowings.

6. Need to seed or fertilize? It's the P-E-R-F-E-C-T time following aeration. The holes you just created are ideal "germination chambers" for seed. Seed that drops into the holes will stay moist, have good contact with soil and be protected during germination. Fertilizer will also reach turf roots better following aeration (be sure to water it in). On a side note, if you applied crabgrass preventer to your lawn this spring, wait until August to seed--the crabgrass preventer will kill seedling grass.

It took Mike about 35 minutes to aerate my 3,000 square foot lawn. And I was thrilled with the result. He did mention that I have a much heavier thatch layer in my front yard (oops) and that doing it again in fall would be wise. So if it's been a few years, do your lawn a favor and aerate! It does the lawn good.
The chickens loved the freshly disturbed earth and had a heyday with worm bits. 

Tuesday, April 21, 2015

Avoiding Abiotic Afflictions …in the spring garden

Posted by: Mary Small, Jefferson County Extension Plant Diagnostic Clinic

Abiotic plant problems are brought on by environmental or cultural conditions. They often mimic disease, but are not caused by any living organism. They plague many gardens and landscapes, even, unfortunately, at the very beginning of the growing season.

Planting seeds is a favorite springtime rite. Once in the soil, they’re watered and watched for what seems like an interminable amount of time. And then….nothing…or spotty germination. More time goes by…hmmm….what’s a gardener to do?

Check the age of the seed.  All seeds don’t remain viable for the same amount of time. For example, corn stays viable for around two years, yet tomato seed is viable for five years. If you are using older seed, you may first want to conduct a “rag doll” test. Take 10 seeds, place down the middle of a paper towel, roll it up and fold the sides under, so seeds don’t drop out. Moisten the paper towel and place in a sealed plastic bag on the kitchen counter. Once the time to germinate has elapsed (found  on the bag of seed), open everything up and see how many seeds have germinated. If 7 out of 10 did, then you have 70% germination. You may want to sow seeds a little thicker to make up for the reduced germination rate.
"Rag doll" test for seed germination
Some seeds produce weak seedlings and may need some help emerging through the soil especially if it crusts over easily.  Carrots are a good  example of this. This year, try planting the seeds as usual, then cover the row with a piece of burlap or a board. This helps prevent soil crusting and allows the tender seedlings to germinate. When it gets close to the expected germination date, lift the covering and start checking the progress. Once most of the seedlings are up, you can remove the covering.
Weak seedlings are the reason radishes are often interplanted with carrots.  The stronger radish seedlings germinate first, making way for the carrots. They’re harvested in about 30 days and create even more room for the developing carrot roots, although thinning may still be needed.
Carrot seedlings planted with burlap
Beans sometimes have germination problems.  If placed in soil that’s too cool, they don’t sprout and  may rot. Even when beans germinate, I often get questions about how to control  “the birds ( squirrels, rabbits or any other critter observed near the garden) that are eating the leaves off the bean plants”. This problem is not caused by animals. It’s called “baldheading” and is caused by mechanical injury to the growing point of the seedling. Crusty soils and damaged seeds are the likely culprits here.
"Baldheading" of beans caused by mechanical injury to seedlings
Sweet corn planted in too cool soil, like beans, does not germinate (or germinate well) and may rot. Supersweet varieties actually need soil temperatures of at least 60 degrees F to germinate.

To check soil temperature, insert a soil thermometer several inches deep into the soil. The soil must be the desired temperature for several days before planting. 

Monday, April 20, 2015

The Bee's Knees!

Posted by: Deryn Davidson, Boulder County Extension

April showers bring May flowers!!  A good saying to keep in mind while our gorgeous weather turns to snow and rain. As the spring season progresses, everything from plants to insects to gardeners begin to wake up and get ready for the season ahead. As plants start to bloom, they of course need to be pollinated to complete their life cycle and who better to do that job, than bees?! Certainly there are many, many other animal and insect species out there that pollinate, but bees are my favorite. 

leaf cutter bee
As you’re out tending your plants and garden beds, take a moment to notice the visitors that are starting to appear at the flowers. Chances are, many of them are our native bees. Most people are familiar with honey bees which hail from Europe, but few realize that we have over 900 species native to Colorado alone! There are more than 3,500 species in the U.S., and there are reports of 20,000 + species world wide. 

Perdita on the head of a Xylocopa. Photo by Stephen Buchmann.
Some bits about our native bees… First off, the majority of them do not sting! There are so many different species that often they are overlooked and/or people just don’t realize they are bees. One that is easy to overlook is the smallest bee species known, the Perdita minima. This little bee is less than 2mm (<0.08 inches). The largest bee found in the US is the carpenter bee which is in the genus Xylocopa; they range in size from 1/2-1 inch. 

ground nesting bee
underground nests
Most of our native bees are solitary, as opposed to the social honey bee who form large colonies of 40,000 + individual bees. You can find evidence of the native bee's nests in dead wood, pithy stems, pre-existing cavities, and in many cases, underground. Knowing this makes it easy to create habitat for these little friends of the garden. Beyond just providing food (flowers for nectar (carbs) and pollen (protein)) you can provide shelter and water which completes the habitat and will make your garden more attractive for them to move in and stay awhile. 

old stumps in the garden provide habitat for native bees

For the cavity nesters you can include a snag (old wood stump or branch) in your landscape or you can build a bee condo (see UC Berkley Urban Bee Lab for more info). For the ground nesters you can leave areas of sunny, undisturbed ground that will be inviting for them to create their little underground tunnels and nests. Keep an eye out for small holes in your soil, it might be the entrance to a bee’s home!!

hives at the WFC
Honey bees are also a lot of fun. I started beekeeping when I lived in Austin, TX. My first hive was a transplant from an established hive that had taken up residence in a duck nesting box. My mentor and I suited up and carefully moved the hive out of the box and into a Langstroth hive (typical white boxes that you think of). It was quite an exciting day! I was able to keep my hives at the Lady Bird Johnson Wildflower Center , where I worked at the time. Those were some happy bees!

honey bee
Here at the Boulder County Extension Office we are working to increase pollinator habitat by planting more gardens and we will be starting up honey bee hives again this spring. Because they are such great pollinators, bees are naturally a gardener’s friend. Without their help, and the help of other beneficial insects, your vegetable garden wouldn't be able produce the bounty that feeds you and your family, and your flower gardens would be less productive. As gardeners who depend on the ecosystem service they provide (pollination), we need to raise our awareness, and help to conserve and create habitat whenever possible. They are our modest companions in the gardens, and when provided with a little food and shelter, they will work tirelessly with us, and our gardens will be all the better for it!

sweat bee

Thursday, April 16, 2015

Crabapple Blooms – A Welcome Sign of Spring

Posted by: James E. Klett, Extension Specialist

Crabapples are popular ornamental trees in Colorado especially along the Front Range of Colorado and their flowering announces the arrival of spring.

Their blossoms appear generally from April to May depending on variety but this season they have appeared one to three weeks earlier than normal. Crabapple flowers may be single (5 petal), semi-double (6 to 10 petals) or double (more than 10 petals). Single-flowered crabapple varieties tend to bloom earlier and currently many are in full bloom. Semi-double and double flowered varieties tend to bloom later in the spring season. Actual dates of blossoming can vary each year depending on weather conditions and this spring they seem to be earlier than normal. Also, the length of blooming period can range from 1 to 2 weeks depending on variety and weather conditions. Cooler weather will prolong their bloom period.

Crabapple flower buds are even attractive before they are fully open, developing color as they swell – called the balloon or bud stage. The balloon may be a different color than the later mature flowers.

Crabapple flowers are a welcome sign of spring and this year’s flower abundance along the Front Range seems exceptionally outstanding.

Colorado State University has been evaluating crabapple varieties for over 30 years for ornamental features and for disease and pest resistance.
A few single flowered forms that have done exceptionally well in our trials include:
  • Cardinal – with pink to white single flowers with reddish new leaves and good disease resistance
  •  Spring Snow – single white very early fragrant flowers with bright green leaves and very popular because it produces no fruit
  •  Royal Raindrops – with single pink to red flowers with cutleaf purple leaves turning orange red in fall
  •  Sentinel – red balloon to white early flowers with upright growth habit and good for narrower spaces

Semi Double Types:
  • Coral burst – has pink to rose semi-double flowers and available in both tree or shrub form and an excellent patio plant
Double Type:
  • Brandywine – has double pink rose flowers that are later to bloom, but has many larger fruits and exfoliating bark. It is one of the better double flowered forms.

By choosing to plant some crabapples of all three types you can enjoy the flowers of crabapples over almost a six to eight week period of time given favorable weather conditions. 

Monday, April 13, 2015

Natural nectar for hummingbirds

 By Irene Shonle, CSU Extension in Gilpin County

In one of the earliest returns I have ever heard of, broad tailed hummingbirds have already been widely reported along the Front Range. I've been waiting all winter for this, although I will probably still have to wait weeks for them to come up to my elevation.

It is easy for those of us who live in the mountains to attract hummers to our yards, but it’s still possible to do so in the city.  This early migration is one of the prime times to lure them in, but you get another chance starting around the 4th of July (when our species count can increase to four – including Rufous, Calliope, and Black-chinned hummers).

Putting out a feeder is usually the first step.  In these early days, a 1 part white sugar to 3 parts water solution is helpful to help the hummers recover from their long migration, but reduce the sugar concentration to 1:4 by the middle of May. Be sure to never put red dye in the feeder, since it is potentially hazardous to their health. The red on the feeders is plenty enough to attract them. 

Another way to entice the flying jewels is to plant some natural nectar.  This will make your yard overall more attractive to the hummers, not only because there will be visible attractants that will cause them to look twice, even flying at 50', but small insects and spiders might take up residence as well.  Hummers spend a lot of time eating small insects, and they need the protein as much as they need nectar, especially when raising young.

Here are some suggested native species that are attractive to hummingbirds:
·         Most penstemons, but especially Penstemon barbatus and Penstemon eatonii.
·         Scarlet gilia (Ipomopsis aggregata) – a biennial, easy to plant from seed
·         Bee balm (Monarda fistulosa)
·         Columbines (Aquilegia)
·         Paintbrushes (Castilleja)  - these are hemiparasites, and should be sown near other perennials.  They can be hard to establish.
·         Wax currant (Ribes cereum) and Golden currant (Ribes aureum)- both shrubs
·         Bee plant (Cleome serrulata)  - annual
Broad-tailed hummingbirds LOVE Penstemon barbatus

Some non-native species known to attract hummingbirds:
·         Maltese cross (Lychnis coronaria)
·         Coral bells (Heuchera)
·         Agastaches  (Agastache) – these work best at lower elevations, or possibly in warmer microclimates
·         Red-flowered yucca (Hesperaloe parviflora)  - only for those at lower elevations
·         Salvias – particularly the red-flowered ones
·         Siberian catmint (Nepeta siberica)
·         California fuchsia (Zauschneria californica)
Broad-tailed hummingbird sipping from Heuchera sanguinea

If you want to plant a container full of annuals to attract hummers, try:
·         Nasturtiums
·         Red annual salvias
·         Geraniums
       Honeybells  (Cerinthe major 'Purpurascens')
If you look hard, you can find the hummer below the honeybells in the upper left. Nasturtium is another favorite. As a bonus, both of these plants are critter resistant (very important in my area!)

Friday, April 10, 2015

Dog Tuff Grass: A New Turf Species?

Tony Koski, Extension Turf Specialist

African bermudagrass (Cynodon transvaalensis)
Beginning in 2014, I began receiving questions about a “new” turfgrass – being sold under the name Dog Tuff ™ African Dogtooth Grass. The sellers of this grass suggest that its Latin/scientific name is Cynodon hybrida.  I have searched databases for this grass and run it by prominent bermudagrass breeders and researchers – with no one recognizing any turfgrass (or grass, for that matter) with the Latin name C. hybrida.  For you plant nerds out there, you can check the validity of any scientific/Latin name at The Plant List, a working list of all plant species (currently contains over 1 million plant species names). If you want to be uber nerdy, you can even see a photo of the earliest specimen of this grass (housed in the herbarium of the Royal Botanic Gardens, Kew), collected in Africa in 1919. The species was officially named in 1921.

C. transvaalensis is a non-native grass, introduced
from the Transvaal region of South Africa.
Soooooo, this is far from a “new” grass. It is a species of bermudagrass, African bermudagrass (Cynodon transvaalensis Burtt-Davy), used by turfgrass breeders since the 1950s to develop new, interspecific turf-type bermudagrass cultivars. Tifway bermudagrass, released in 1960, has C. transvaalensis as one of its parents. African bermudagrass (AKA couchgrass, African dogstooth grass) is a native of the Transvaal region of South Africa, where it can be found growing on the high grass prairie (veld). This region of South Africa experiences sharp day (70s-80s)/night (30s-50s) temperature differences, and receives 18-24 inches of precipitation annually.

C. transvaalensis can produce a dense turf.
I have been growing this grass at CSU for many years, after finding it in a Denver lawn during the 2002 drought. It forms an attractive, dense sod. The leaves are very fine textured, and the grass spreads aggressively via stolons and rhizomes. It has excellent cold hardiness (one reason it is used as a parent in bermudagrass breeding programs). Left unmowed, it grows to a height of 3-6 inches, depending on how much water and fertilizer it receives. Because of its aggressive, dense growth, few weeds will appear in this turf. However, during the warmest times of the year, mowing will often result in scalping – causing a brownish appearance. Because of this tendency to scalp when mowed, it will probably look more attractive if left unmowed (or if mowed frequently…as in 2-3 times weekly during the summer).

Like all bermudagrasses, C. transvaalensis spreads
by aggressive stolons ('runners')
If this grass is so ideal, why don’t we see named cultivars on the market from breeding programs or sod producers – as is the case with other turf species? It’s because breeders recognize the limitations of C. transvaalensis as a turf grass by itself. It will tolerate very low mowing heights, but the tendency to scalp during the summer (even when mowed daily) is seen a as major impediment to using it as a turf on golf courses or for sports turf.  Its greatest value remains as a germplasm source for the breeding of cold-hardy, fine-textured, high-quality hybrid bermudagrasses. Those considering this grass should also be aware that it is a warm-season grass (like buffalograss), so it will green up sometime in May and become dormant/brown with the first hard frost in the fall.

Bermudagrass is one of few grass species that
spreads by both rhizomes and stolons - a growth habit
that makes it both a traffic-tolerant turf and a potentially
troublesome and difficult-to-control landscape weed
While some may find this grass useful as an aggressive ground cover for certain high traffic areas (dog runs, for example), it is important to recognize the potential for this plant to become a weed in the home landscape. In fact, the reason I found the C. transvaalensis that I currently grow at CSU is because of a homeowner request to ID a weed in their landscape. In recent years, one of the most common weed submissions (samples in the mail, or photos sent by phone or email) I receive throughout the summer is bermudagrass in home landscapes (lawns, shrub and flower beds, vegetable gardens) and on golf courses. In some states (including our neighbor Utah), bermudagrass is listed as an invasive species. In other words, be aware – if you decide to plant this grass – that is has the potential to spread into places where it might be unwanted. And…it can be remarkably difficult to eradicate…requiring multiple applications of glyphosate over an entire growing season.

Bermuda is a warm-season grass, so will have a long
winter dormant period in Colorado
So, yes, it is in many ways a tough grass – because it is bermudagrass. Remember: the perfect turfgrass (for every lawn situation) has not yet been discovered or developed by breeders. Every species has its positive and negative sides – and this one is no exception.

Friday, April 3, 2015

The Glory of Augusta National Golf Club

Posted by: Alison O'Connor, Larimer County Extension
My dad, Bill, and me in front of the 12th green at Augusta National in 2001
I’m an avid golfer and I love the game of golf. I started playing when I was ten years old, because that’s what you did in my family. Everyone plays golf. My grandparents played well into their 70s and to me, investing in a lifetime sport is one of the appeals of this incredibly frustrating (yet rewarding) game.

The second week of April really kicks off the start of the golf season with the Masters at the Augusta National Golf Club in Augusta, Georgia. Even if you’ve never picked up a club, I would hazard a guess that you’ve heard of this tournament. Cue the soft, gentle music, Jim Nantz’s narratives and views of Rae’s Creek with hours of coverage on CBS…

The Augusta National Golf Club is probably one of the most recognized courses in the world and could be America’s “St. Andrews.” What many view as an elite and extremely private golf course, it has humble roots. Prior to the course’s construction in the early 1930s, the land belonged to Fruitlands Nursery. Each hole on the course is named after a tree or shrub. Though a few holes have been renamed over the years, this link to horticulture is unique.

The course was the mastermind of Bobby Jones, one of the most famed golfers of all time, and Alister MacKenzie, an English golf course architect (he also designed Cypress Point in Pebble Beach,
CA and the Scarlet Course at The Ohio State University). The land of Fruitlands Nursery was purchased in 1931 and the course opened for play in January 1933; the first tournament was held in 1934 and was (then) named the Augusta National Invitation Tournament.
Bobby Jones
The history and landmarks of the course are extensive. I’ve mentioned Rae’s Creek, which eats balls like a hungry hippo, and meanders along the back of the 11th green, in front of the 12th green and is the course’s lowest point in elevation. The creek was named after former land owner John Rae. Two bridges cross Rae’s Creek, named after Ben Hogan and Byron Nelson.

Rae's Creek and the Hogan (front) and Nelson (back) Bridges with the 12th green
Last winter, the Eisenhower Tree, a loblolly pine, made headlines when it was removed from the 17th hole after suffering extensive damage from an ice storm. It was named after Dwight Eisenhower who lobbied to have it removed in 1956 after hitting it so many times. Ike finally got his wish in February 2014.

“Amen Corner” was coined in 1958 by Sports Illustrated writer Herbert Warren Wind. The corner is a combination of shots at the 11th, 12th and 13th holes. It was nicknamed Amen Corner because it often contains some of the most exciting shots during the tournament and where it can make or break a player’s score (remember Rae’s Creek is in play!).

My former college roommate had the opportunity to do a six-month internship at Augusta during our days at Iowa State. She also had an open invitation to volunteer at the tournament in the years following her internship. She worked seven tournaments and has intimate knowledge into the preparation that goes into the Masters. When I was on my way to Georgia for my own summer internship, my dad and I had the once-in-a-lifetime opportunity to visit Augusta, step foot on the “slick as concrete” greens and walk over Hogan’s bridge. It was thrilling and a total “Bucket List” item for a golf nut like myself.

A few things she learned during her time at Augusta:

  • The flowers that make up the Masters “map” are yellow pansies in the fall and yellow marigolds in the summer. In case of a catastrophic event, enough plants are grown in an on-site greenhouse to replace the flowers if necessary.
    The "map" of yellow pansies in front of the clubhouse
    (photo from
  • Augusta may be most recognized for the pink-blooming azaleas during the tournament, but there are actually hundreds of flowering shrubs that encircle the golf holes, such as: flowering quince, native and cultivated azaleas, banksia rose, forsythia, dogwood and redbuds. While some bloom earlier than others, the combinations and diversity provides a near-constant palette of color.
  • Rae’s Creek is sometimes dyed black to reflect the landscape better (and provide a better television-viewing experience).
  • Augusta closes in mid-May and opens again in mid-October. During the summer, the course undergoes extensive renovations and reseeding efforts. Staff and volunteers may play one round of golf before it closes for summer.
  • Hundreds of volunteers help make the tournament a success and come from all across the world.
  • Each green has a SubAir rootzone ventilation system, which cools and provides oxygen to the roots of the bentgrass. Bentgrass is a cool season species, which typically doesn’t perform well in the Deep South (it’s very humid and hot!). Even with this sophisticated system, the greens may still need to be hand-watered several times a day.
  • The budget for the golf course operations has never been made public.
  • The course is overseeded with perennial ryegrass each fall; the ryegrass dies out during the hot summer months and the bermudagrass thrives.
  • The scoreboards are not digital and are manually changed by people working the tournament.
  • No motorized golf carts are allowed on the course—caddies, who wear white jumpsuits, are required. 
  •  The course, compared to the average U.S. golf course is very large, with a total footprint of 365 acres (U.S. average is 150 acres); 100 acres of the course are fairway (compared to an average of 30 acres of fairway for a typical course). The rough encompasses 30 acres (the average is 50 acres). That said, if you’re not accurate at Augusta, you’re in the trees and will be hitting off pine mulch.
  • Augusta also has a par 3 course on the grounds that is maintained to the same standards at the 18-hole course.
The course invited its first women members in 2012 (not a moment too soon!) and a few notable members include Condoleeza Rice, Warren Buffet and Bill Gates. The golfer who wins the Masters each year does not become a member, but does receive the famous green jacket. The winner of the Masters is the only person who can remove a jacket from the grounds and wear it outside of the golf club—but just for one year.
The famous Green Jacket
I know that many find watching golf on television about as thrilling as watching paint dry, but the Masters never disappoints. If nothing else, catching a nap while listening to the whispering of David Feherty of what club Rory McIlroy selects for his approach to the green, is the sign of a restful weekend. Now the big question is: Will Tiger be a contender? Personally, I’m rooting for Bubba.

Golf nails! I'm ready for the Masters.