Do Japanese Beetles Prefer Some Roses More than Others?

Colorado roses have been attacked by Japanese beetles for several years, leaving behind ravaged foliage and deformed flowers. Curiously though, some gardeners report that their roses suffer little to no damage from the insect. Are some rose cultivars less enticing to the Japanese beetle than others? This was the focus of Colorado State University’s 2016 observational study conducted at Littleton’s War Memorial Rose Garden. In the first year of this multi-year study, the following rose cultivars were not found to be damaged by Japanese Beetles: Angel Face, Debut, Hondo, Joseph’s Coat, Mardi Gras, Picotee, Popcorn, Prima Donna, Ralph Moore, Singin’ in the Rain and White Lightnin’.

Conversely, the following cultivars were observed to have the highest levels of Japanese beetle destruction: Pink Promise, Honey Perfume Whisper, Love and Peace, Day Breaker, Strike it Rich, Cherry Parfait, Eureka, Starry Night, Rainbow Knock Out, Lady Elsie May, Carefree Delight and June Lover.

Adult Japanese beetles destroy flowers at the same time bees are gathering pollen, making their impact even more significant. For this reason, CSU’s study identified roses with high Japanese beetle susceptibility and high visitation by bees. Topping this list were Rainbow Knock Out, Lady Elsie May and Strike it Rich. Also in this group were Prominent, Home Run, Easy Does It, Apricot Nectar, Gemini, Starry Night, Baby Boomer, Sweet Diana, Julia Child, Cathedral, Betty Boop, Mon Cherie and Cloud Dancer.

Early findings suggest that gardeners may be able to lessen damage to roses by planting cultivars that are less attractive to Japanese beetles. It also underscores the importance of close monitoring and care of plants to reduce the effects on pollination. In the future, additional information on why some cultivars are preferred over others is likely to emerge.

This CSU publication provides comprehensive information on caring for plants infested with Japanese beetles, the larvae stage effecting turf and more. An additional bit of advice – it has recently been found that crushing the Japanese beetle does not attract more beetles. So, while we’ve previously been advised to handpick and drown the insect in soapy water, feel free to stomp on them too. Since they are night feeders, they are easiest to find around dusk, when they are about to feast on your plants.

Written by Linda McDonnell, a Denver County Master Gardener

Note: The study cited in this post was presented to the Denver County Master Gardener Association by Dr. Whitney Cranshaw of Colorado State University in May 2017.

Photos courtesy of http://www.pixabay.com

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Slow Food Helps Grow Kids

An important part of the children’s garden was helping kids connect to nature by learning about the colors and magic of fruit. Other beds were filled with all the plants needed to make salsa, a nutrient scavenger hunt and salad greens as an equation for success.

There was a lot to love about the Slow Food Nations festival in downtown Denver over the weekend.

The celebration of local, organic and sustainable foods included free food tastings offered by Slow Food groups from around the world, educational programming and vendors selling to the thousands of foodies that attended the event.

But one of my favorite displays was the children’s garden, located on the sidewalk just north of the Taste Marketplace.

In this series of raised bed gardens, kids had the chance to get their hands dirty by exploring gardens filled with fruits, vegetables, herbs, grains, and flowers.

One of the premier gardens included a sample of the modular Learning Gardens, created by The Kitchen Community. The Kitchen Community’s mission is “Community through Food” and it accomplishes that goal by building outdoor classrooms on school playgrounds around the country, including Denver and Fort Collins. There are more than 400 to date.

The customizable gardens are designed to fit into each school’s landscape and become part of the educational process. As a teaching tool, the gardens help students learn about growing and eating nutritious foods and gaining healthy habits to hopefully last a lifetime.

A bowl of dried corn and a grinder were placed next to a bed of corn plants. Kids were encouraged to try their hand at turning corn into a grain for cooking.

 

 

 

 

 

 

 

 

 

The Low Tunnel garden bed introduced kids to the the concept of helping plants grow before and after summer. Books on year-round gardening surrounded the bed as resources for kids and their parents.

 

 

In addition to all the herbs, fruits, and vegetables, there were beds of flowers to promote planting for pollinators. A sensory garden helped kids see, smell and feel the benefits of plants.

 

 

 

 

 

 

 

 

 

By Jodi Torpey
A Denver Master Gardener

TREES, glorious trees

Trees. They are all around us.  In our gardens.  In our parks.  On the street.  Yet we barely notice them most of the time.  Gardeners tend to forget that they are plants like any other.  Non-gardeners tend to regard them as more or less permanent objects in the landscape.

I’ve recently been helping with the Al Rollinger Tree Survey being done by Denver Botanic Gardens and The Denver City Forester’s Department.  (For more information on this, see www.botanicgardens.org/rollinger-tree-collection-50-year-survey-project.)  This has taken me to different parts of the city, looking at trees in yards and on the street.  For each tree in the project we identify the tree, measure its diameter and height, assess condition, take a photo and get the GPS location. This close examination has given me a new appreciation of these giants of the plant world.

Denver is at the western edge of what was once short grass prairie all the way to Kansas City.  Trees are not native to this landscape apart from the odd plains cottonwood near water.  All the trees planted and growing in our city are imported here, whether from the higher ranges in the mountains (pine, spruce, aspen) or from the north and east (maples, oaks).

Why plant and grow trees?

Yes, it can be difficult to grow healthy, long-lived trees here.  Too little water, alkaline soil, heavy clay, too hot in summer, too cold in winter, traffic pollution, concrete and blacktop suffocating roots.  These are the same problems that challenge us in our back yards as we try to get our shrubs and flowering plants to perform for us. But with a little care and attention, we can grow healthy trees. Just look at the many benefits trees bring:

Environmental/Health

  • Provide oxygen
  • Reduce carbon dioxide levels
  • Improve air quality through absorption of pollutants
  • Absorb and retain water to reduce run-off and delay onset of peak flow (flooding)
  • Reduce soil erosion
  • Improve capacity of soil to absorb water
  • Provide animal, bird and insect habitat
  • Reduce noise levels
  • Reduce stress
  • Reduce UV exposure

Energy

  • Shade and cool our homes and streets
  • Save energy (natural cooling through shade v. AC)
  • Provide wind breaks

Social

  • Increase property values and reduce crime
  • Improve walkability of neighborhoods
  • Provide beauty

Get to know our trees

You can find out about every single tree growing in the street and public rights of way in Denver by typing in an address in the city’s “Treekeeper” program at http://beasmartash.org/do-i-have-an-ash-tree/interactive-map.  When I walk the dog around the neighbourhood, I look up now and try to identify the trees I walk by (or underneath).  If I don’t know one, I take a note of the address and check on the Treekeeper when I get home. (Because of the vast amount of data involved, the program doesn’t work well on a mobile device.)

Some trees are “champions”. These are trees that have attained a large size (based on species) through girth, height and crown size.  You can find out about Colorado State Champions here www.coloradotrees.org/wp-content/uploads/2016/06/2016-Website-Champs_Alpha.pdf and National Champions here www.americanforests.org/explore-forests/americas-biggest-trees/champion-trees-national-register/. 

Choosing and buying a tree

A tree can be a big financial investment and selecting the appropriate tree is very important if you want it to not just survive but to thrive for many years.  The CSU Extension Service publishes a very helpful list of trees recommended for the front range. You can find it here: www.extension.colostate.edu/docs/pubs/garden/treereclist.pdf

The non-profit organisation, The Park People, has a scheme called Denver Digs Trees for selling street and yard trees at subsidised prices (or even for free in some locations) every year.  The trees they sell are all considered suitable for Denver. You complete an application form in January or February and the trees are distributed in mid-April.  They will even come and plant your tree for you if you need help. You can find them here:  www.theparkpeople.org/Programs/DenverDigsTrees.aspx

Look for trees in Colorado nurseries and garden centers which grow their own trees.  A tree which started life here is likely to be better adapted to Colorado growing conditions than one imported from another state.

Before you plant

When planting a tree whether in your yard or the street, you need to get the position of all utility lines checked before digging . You can get the utility lines checked for free by calling 811.  You also need a permit from the City Forester before you plant a tree in the street i.e. the public right of way.  The permit is free and can be obtained by email. See here for details:

www.denvergov.org/content/denvergov/en/denver-parks-and-recreation/trees-natural-resources/forestry-trees-/property-owner-resources.html

Tree problems

Like all plants, trees can have problems.  Pests and diseases or hazards caused by natural events, like storm damage.  Often problems stem from human actions.  Improper planting, insufficient or too much irrigation, damage from garden tools like mowers and weed-whackers, root damage from nearby construction, damage from staking and guy wires, pet damage, root damage from landscape fabric or inappropriate mulching e.g. river rock.

Emerald Ash Borer

The biggest problem facing trees in Denver right now is the threat of the Emerald Ash Borer (EAB). This pest came from Asia where their ash trees are immune to it.  Unfortunately, American ash trees are not.  Its presence has been confirmed in Boulder since 2013 and in Longmont since 2016.  It threatens to wipe out all the ash trees in Denver if (when?) it gets established here.  That’s 1 in every 6 trees in Denver or 1.45 million trees.  For information and advice about EAB go to http://beasmartash.org/.

To try and mitigate the effect that EAB will have on our city trees, the City Forester’s Dept, in association with The Park People’s Denver Digs Trees program, is offering new street trees now for FREE.  By planting in advance of the arrival of EAB, the aim is to mitigate the effect of the EAB and increase diversity in the city’s tree population. You don’t need to have an ash tree already or any kind of street tree, just room to plant a new one.  To apply for a new street tree, go to www.beasmartash.org/what-can-i-do/apply-for-a-tree/.  They will even plant it for you!

Learn more about trees and get involved

The Park People run a program with Denver’s City Forester’s Dept which trains volunteers to become Community Foresters.  Volunteers assist the City Forester’s Dept by becoming qualified to lead and participate in tree planting and tree care projects in their neighborhoods.  Courses are run every year.  More information can be found at  www.theparkpeople.org/programs/communityforester.aspx

Get more information about trees

You can find useful information and get advice on all aspects of trees from the following:

Your local City Forester (arboreal inspector) – find him/her at www.denvergov.org/content/dam/denvergov/Portals/747/documents/forestry/forestry-inspections-districts-map.pdf

CSU Extension Service ‘Ask an Expert’ – ask.extension.org/groups/1955/ask

Ask a Master Gardener – www.cmg.colostate.edu/ask-cmg.shtml

The Park People – www.theparkpeople.org

The Colorado Tree Coalititon – www.coloradotrees.org/

A professional arborist – see the list of arborists licensed to operate in Denver at www.denvergov.org/content/dam/denvergov/Portals/747/documents/forestry/DPR-Forestry_current-licensed-contractors.pdf

Look up, learn more and enjoy our trees!

 

Anne Hughes/A Denver County Master Gardener

Photo by Anne Hughes

 

 

 

 

Rabbits!

rabbit-717855_960_720With apologies to Bugs, Peter and Thumper, rabbits are real pests in the garden. Parts of the Denver metro area are inundated with them, while others are not – at least yet. I’ve been seeing them in my central Denver neighborhood for the last few years. They reliably devour my lettuce each spring  and feast on Goldstrum Rudbeckia in August.

If you’re not sure if rabbits are the culprits to your plant damage, look for clean, 45 degree angle cuts, mowed down seemingly overnight. Damage is usually up to 24″ high and most often on tender new growth.

While a hungry rabbit will eat many plants, in the vegetable garden they prefer young tender shoots of lettuce, beans, squash  and broccoli.  They also love to munch on many ornamentals such as black-eyed susans, pansies, marigolds, petunias, gazania and ornamental grasses.

Nothing will completely deter a brazen bunny, but a combination of the following practices may curb their ways.

Fencing – Erect 3′ high barriers with chicken wire with 1″ mesh openings around your garden plots. Rabbits love to burrow, so be sure to bury the fencing 6″ deep.

Plants – Colorado State University reports that sedum, foxglove, iris, lambs ear, red hot poker, yarrow, yucca, apache plume and blue mist spirea are somewhat rabbit resistant. Rabbits’ taste buds vary just as ours do, so no plant is 100% off-limits.

Predators – Wildlife such as foxes, coyotes, hawks, adult owls and rattlesnakes will send rabbits packing. So will your cat or dog, who will get the added benefit of a good workout from chasing bunnies.

Repellents – Products containing capsaicin (pepper extract) , castor oil, ammonium salts or predator urine can be effective when sprayed to a height of 3 feet and reapplied after heavy rains or watering. Some newer eco-safe sprays deter rabbits and deer, are less effected by moisture and emit a long-lasting scent (undetectable by humans) which repel rabbits. These are not recommended for edible plants.

Winter Care – Rabbits feast on our landscape in the winter by chewing on woody shrubs and the bark of your trees (fruit trees are a favorite). Protect these plants with fencing. Also remove thick underbrush and tall weeds and grasses which create comfy winter shelter. Seal up openings around decks, sheds and crawl spaces, too. By removing an inviting resting place, rabbits are encouraged to seek shelter elsewhere.

Have you had success in preventing rabbit damage?

References:

http://planttalk.colostate.edu/topics/wildlife-issues/2305-ravishing-rabbit-revenge

http://www.denverpost.com/2013/06/19/bunny-rabbit-plague-hits-colorado-gardens-what-to-do/

Photo Credit:

www.Pixabay.com, a source for royalty free images.

Written by Linda McDonnell, Denver County Master Gardener

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Grandma Always Said: How To Research Gardening Questions Effectively

IMG_20170228_123941189“Roses won’t do any good without blood.” my grandma always told me as, small girl, I watched her dump buckets of chicken blood over the roots of her roses in rural Wisconsan. Of course, she also told me roses planted during the waning moon would die straight away.
My grandma’s gardening practice was full of these details: fish heads in the holes dug for new lilacs, red thread tied around apple branches to protect them from blight. I still keep her copy of The Farmer’s Almanac fondly among my folklore books….but I don’t get my garden advice from it.
Gardening is a mystical business, half art and half science. Folklore abounds, and any gardening question will have five answers, three of them odd or downright off the wall.
The internet has not helped this issue in the slightest. Type ‘kill weeds in the garden’ into Google and you’ll get hundreds of answers, ranging from reputable to rapaciously folksy to alarming in the extreme. For example, I once read a recommendation for turpentine and salt to kill prickly lettuce around peonies. You get the idea….
So how does a gardener sort through the chaff to find the information they need in this muddle?
Here’s a quick checklist of the Four Research Rules, to help you vet your sources!

Reputable URL

When doing a web search, focus on URL’s with an ‘.edu’ ending. This means that an educational body has collected, researched and put out the information for public education and it should be fairly unbiased. If the site ends in .com, chances are a company is involved, and that can skew answers towards ‘buy this to fix your problem!’ The research is also more reliable on educational websites than on your garden-variety blog.

Reliable Information: The Most Accurate Information For Today

As with any other field, information on best garden practices changes with time. I generally ensure that my garden books are no older than 1970, and prefer books printed in the 90’s or later.

Repetition: It Makes Reputation

If only one source or one gardener is talking about a method, you might want to be wary. Best practices tend to spread, so if there’s no existing research on a method of doing something, you might want to try it as an experiment but don’t  rely on it until it’s proven.

Research!
If your source isn’t citing other sources or is using anecdotes to endorse a recommendation, buyer beware! Look for solid research, sources that you can look up yourself and references to specific studies, field trials, or specific experimental examples of the product/method/concept being applied. Some garden books are written poetically and that’s fine, but make sure there’s solid research under the fine words.

Happy garden researching!

-Olivia Wylie, Master Gardener

New CSU Resource Targets Emerald Ash Borer

Colorado is preparing to battle a tiny insect that’s destined to change the way our urban forest looks. The Emerald Ash Borer (EAB) is already in Boulder County, and it’s only a matter of time before this destructive pest is found in nearby counties.

Every single ash tree that lines the streets of our neighborhoods is at risk. The EAB loves these trees that make up about 15 percent or more of all city trees.

The newest weapon in the fight is a mobile app. Colorado State University Extension and the Colorado Forest Service joined together to create a free app to help with early detection of the EAB menace.

The app is easy to download to Apple and Android-based mobile devices. Just search for “EAB/Ash Tree ID.”

The app walks users step-by-step through tree identification to determine if the tree is an ash and susceptible to the EAB. If it’s an ash, there are more resources for EAB symptoms, management and links to much more information.

It’s important for tree owners to be aware that ash trees are already at risk so they can be prepared. It’s better to consider management and treatment options sooner rather than later.

The EAB/Ash Tree ID app is the latest tool in the Colorado campaign to raise awareness about the insect pest that has already killed tens of millions of ash trees across the states.

The Be a Smart Ash program, sponsored by the City of Denver, started its communications campaign last year. The Colorado Department of Agriculture is also actively involved in fighting the EAB.

Laura Pottorff with the Colorado Department of Agriculture, leads an excellent one-hour webinar called “EAB: Myth or Monster” for Colorado Master Gardeners. The webinar (taped in May) is available through the CMG online continuing education program and will give master gardeners the information they need to provide research-based information to their communities.

All these resources will help tree lovers start thinking about their options for managing the ash trees in their landscapes. Approaches include replacing ash trees now, planting new trees to take the place of an ash tree in the future, and researching the insecticides to treat trees when the time comes.

By Jodi Torpey
A Colorado Master Gardener

Five Annuals for the Garden

Perennials, shrubs and trees are the undisputed stars of landscape design, providing structure, texture, longevity and nourishment for pollinators (especially native plants). But annuals, too, can play a valuable role for their ability to fill out a maturing garden and infuse color when perennials have finished blooming.  Design-wise, these “one season wonders” offer a chance to change things up from year to year.  For the short-term renter or impatient gardener, annuals offer speedy gratification.

If you’re thinking “petunias, geraniums, marigolds – been there, done that,”  keep reading. Here are five other easy to grow annuals for sunny locations which will thrive when planted among plants with the same moisture needs.

CLEOME

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Cleome, or spider flower, is the tall kid in the back row. Intricate, long-lived  blossoms (6+ inches across) in shades of white, purple or pink will attract hummingbirds and pollinators. Seed pods create interesting tendrils. Xeric once established, plants can reach 5′ tall by the end of the summer. Let some seed drop and they may return next year.

RUBY MOON HYACINTH BEAN  (Dolichos lab lab)

Move over wisteria and clematis, this Plant Select vine is a show stopper. Burgundy tinged foliage with dark stems which support abundant amethyst flowers. In late summer, this vigorous vine is covered with large dark purple bean pods. Grow it on a trellis, let it climb a fence or freely mound in the full to partial sun garden.  Learn more about Ruby Moon here.

LOVE-IN-A-MIST (Nigella damascena )

Love-In-A-Mist sounds like the title of a romance novel, doesn’t it? This delicate, tough plant bears 1″ blue, white, lavender or bicolor flowers which bloom atop 8″ to 12″ finely cut “misty” foliage. It is best grown from seed but occasionally available as seedlings. The bloom morphs into an oval, burgundy striped seed pod which rivals the flower in beauty. Let it reseed for next year, but also treat yourself to some flower and seed pod cuttings.

COSMOS (Cosmos bipinnatus)

Single 2″ to 3″ daisy-like flowers seem to dance above 24″ finely cut foliage. Popular varieties come in pastel/white mixtures; a newly introduced dwarf cultivar is available too. Cosmos can be started from seed or purchased in 4 packs. Don’t let their delicate appearance fool you, they prefer low water conditions and strive in the summer heat. One caution – over fertilizing results in lush foliage and far fewer flowers. Cosmos are a long-lived cut flower, excellent planted in mass and attractive to birds. Will reseed easily, occasional deadheading keeps them at their best.

SUNFLOWER (Helianthus)

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Big and little kids alike delight in watching sunflowers grow. Sow some seeds in the spring and you’ll thank yourself later – so will the birds. If you prefer, keep your eyes out for sunflower transplants at the garden center. Visit Smart, Smiley Sunflowers for information on the wide variety of cultivars, including shorter and multi-branching options.

Written by Linda McDonnell, a Denver County Master Gardener

Photo credits:

Ruby Moon Hyacinth Bean: Plant Select

Sunflower: Jodi Torpey, Denver County Master Gardener

Cosmos, Cleome and Love-In-A-Mist: Pixabay.com, a source of royalty free images

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The Season Of Vigilance: Noxious Invasives, Introduced Weeds And You

-Olivia Wylie, Master Gardener Denver

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The saying goes ‘a weed is a flower whose virtue hasn’t been found yet.’
But you have to wonder with some of the weeds in the garden. What exactly, you think as you sweat and tug, is the virtue of bindweed’s strangling grip on other plants and your garden? What’s the virtue, you think with nervous venom as you pull on your gloves, of a spurge that can give you blisters, kill your dog, and is invasive?!

Unfortunately, the virtues of these plants are exactly what makes them weeds. Adaptability. Tenacity. Ability to survive harsh conditions. It sounds like a compliment when you’re reading a garden catalog, but with the wrong plant in the wrong place, it’s a recipe for disaster on a garden-wide, city-wide or even state-wide level.

Sadly this disaster has played out many times, and today we carry the burden of our forbears’ horticultural mistakes across the country. To combat this issue, a Federal Noxious Weed act was passed in 1974, and our own Colorado Noxious Weed Act was passed in 1996. The Act supports the creation of programs to combat the invaders, and the Department of Agriculture maintains a list of plants to look out for called the Colorado Noxious Weed List.

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This list is invaluable as a resource, and is broken down into several sections. Quoting from the Colorado Department Of Agriculture,

List A Species in Colorado are designated by the Commissioner for eradication.

List B Species are species for which the Commissioner, in consultation with the state noxious weed advisory committee, local governments, and other interested parties, develops and implements state noxious weed management plans designed to stop the continued spread of these species.

List C Species are species for which the Commissioner, in consultation with the state noxious weed advisory committee, local governments, and other interested parties, will develop and implement state noxious weed management plans designed to support the efforts of local governing bodies to facilitate more effective integrated weed management on private and public lands. The goal of such plans will not be to stop the continued spread of these species but to provide additional education, research, and biological control resources to jurisdictions that choose to require management of List C species.

Watch List Species that have been determined to pose a potential threat to the agricultural productivity and environmental values of the lands of the state. The Watch List is intended to serve advisory and educational purposes only. Its purpose is to encourage the identification and reporting of these species to the Commissioner in order to facilitate the collection of information to assist the Commissioner in determining which species should be designated as noxious weeds.’

But we all know what happens when we leave the work up to the government and sit on our laurels. It’s up to every gardening citizen to know your noxious invasives, your invasives, your introduced weeds and what to do about them!

Know Thy Enemy

We could spend entire articles on the exact definition of invasive species, and in fact a wonderful white paper on the subject can be found at this link. But here’s the skinny.

niNoxious Invasive- the long winded definition is quoted from the 1974 Act, and runs ‘Noxious Weed means any living stage, such as seeds and reproductive parts, of any parasitic or other plant of a kind, which is of foreign origin, is new to or not widely prevalent in the United States, and can directly or indirectly injure crops, other useful plants, livestock, or poultry or other interests of agriculture, including irrigation, or navigation, or the fish or wildlife resources of the United States or the public health.’

Put plainly, not only will Noxious Invasives make you livid, they can make you sick. These are the true thugs of the plant world. Generally these beasts will be found on the Commissioner’s A list. These include vile things like Myrtle Spurge/ Donkey Tail Spurge, Euphorbia myrsinites. Originally introduced as a ‘lovely and tenacious rock garden addition’ (a direct quote from an old seed catalog, the company shall remain unnamed!)  it was indeed tenacious. TOO tenacious. And if you decide to pull the stuff, it retaliates with sap that causes painful blisters. Get it in your eyes? You’re taking a trip to the ER my friend. Dogs that encounter the sap can actually die. Not such a great addition after all, and if you see it in your garden it needs to be eradicated by (almost!) any means necessary. Before you tackle it, PLEASE pull on goggles, a long sleeve shirt and pesticide-grade gloves. In fact, I prefer to pull on a thin pair of fabric gloves and my nitrile pesticide gauntlets go on over those. You can never have too much protection.

dtInvasive Species-  an invasive species is best defined as a non-native plant that could cause harm to the native ecosystem by competition pressure. When you pull prickly lettuce before it smothers your lovely little columbines, that’s a perfect example. These plants are tougher, more prolific, easier spreading or in some way advantaged over other plants, and if allowed will run roughshod over our native flora.
Dalmatian Toadflax is the classic example. I’ve taken out of town friends on a drive through the foothills and heard them exclaim ‘oh look at that yellow field!’ I look over and give a heartfelt groan, because I know that field has nothing living in it save a single invading species that has choked out native plant life.

isIntroduced Species-Where list A Noxious Invasives could be compared to a plant felony, plants that fit the Introduced Species are more of a misdemeanor: they’re trouble, but not ecological disaster. Defined as ‘an organism that is not native to the place or area and has been accidentally or deliberately transported to the new location by human activity’ in the 1974 Act, they’re your neighbor’s old mint bush sending shoots into your yard. In my Capitol Hill neighborhood, the quintessential example is the Cap Hill Weed (no not THAT weed),Campanula rapunculoides or Creeping Bellflower. Local lore says it was introduced in the 1920s to grace the great old mansions that once stood in their majesty along these streets, and it’s been with us ever since. It wanders from garden to garden in the older parts of town, sneaking under trees and into small areas, worming into bare spots in the grass and gaining a foothold most anywhere. Some people have simply accepted it as a garden plant like their grandmothers did, but most of us fight it tooth and nail because we’d like to have a garden with more than one plant in it!

Fighting The Good Fight

Delving into reclamation and eradication tactics for species that are toxic, invasive or introduced pests is a paper in itself, and many have been written. The Colorado Noxious Weed Species List has details on the treatment of every species it lists. But here’s some general tips.

  • Safety First. Wear gloves, wear long sleeves, wear safety glasses or goggles if you run any risk of getting poked in the eye or sprayed with sap
  • Get The Root!  Pulling does little good if there’s a root stocked with nutrients ready to shoot up new leaves under there. If you use pesticides, make sure your choice specifies ‘kills the root’.
  • Tenacity Is A Virtue. Don’t get discouraged if the plants come back again and again. keep using your favorite eradication method, and you can wear these invaders out!

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Pretty Tough Plants Book Review

I love the name of the new book by the experts at Plant Select. Pretty Tough Plants describes the family of Plant Select plants perfectly.

If you’ve grown any of these beautiful plants that are so well-suited to our gardens, then you know what I mean. If you haven’t grown any Plant Select recommendations, what’s stopping you? These are the plants that can help you be a more successful gardener.

Plant Select calls itself “a nonprofit collaboration of Colorado State University, Denver Botanic Gardens, and professional horticulturists.” I call it one of the best plant testing and introduction programs in the country.

Pretty Tough Plants: 135 Resilient, Water-Smart Choices for a Beautiful Garden (Timber Press, 2017) is a follow-up to Durable Plants for the Garden: A Plant Select Guide published in 2009.

This new edition seems to be more user friendly, both by its manageable size and in the plant presentations. Plants are divided into groups that include tender perennials and annuals, petites, groundcovers, perennials, grasses, vines, shrubs, and trees and conifers.

Each Plant Select description includes its scientific name, common name, mature size, flower type, bloom time, and best features. Understandable icons give details on sun and water requirements, as well as if the plant attracts pollinators or if deer resist browsing it.

The “Landscape Use” information is meant for gardeners who have difficulty matching plants to place or are unsure of how to combine plants for the most striking effect. The descriptions make suggestions for perfect placement and the best Plant Select companions.

Many of the gorgeous, full-color images show both a close-up view of the plant and a shot of how it looks in the landscape when in full bloom. One of my favorites is Redleaf rose (Rosa glauca) shown as a fabulous specimen plant, and closeups of the star-like single pink flowers and brilliant red hips.

An especially nice feature for this volume is the Plant Reference Guide in the back of the book. This guide provides a quick resource for matching the right Plant Select plant to the right spot in the landscape.

Besides the typical categories, there are two additional and interesting categories: Special landscape use and North American roots. Not every plant has a special landscape use, but when a plant is recommended for “dry shade, cold hardy,” like Denver Gold columbine (Aquilegia chrysantha), gardeners can trust the endorsement.

Prairie Jewel penstemon (Penstemon grandiflorus) is one Pretty Tough Plant in my xeriscape.

I’ve grown many different Plant Select recommendations in my perennial beds, and I can vouch for their resilience – one of the seven qualities a plant has to have to be added to the program.

In addition to being able to stand up to a challenging climate, Plant Select plants have to thrive in a variety of conditions, be water smart, have that “it” factor, resist insect pests and plant diseases, offer long-lasting beauty, and aren’t invasive.

I can tell Pretty Tough Plants was a labor of love by a group of passionate plant people. The photo credits read like a list of area Who’s Who, from well-known horticulturists to CSU Extension Master Gardeners. Pat Hayward and David Winger had the happy task of sorting and selecting images, including many of their own.

By Jodi Torpey
A Denver Master Gardener
(Timber Press provided a complimentary copy of Pretty Tough Plants for this review.)

Sheet Mulching Re-visited

Last week’s blog included a link back to our October 2016 blog on experimenting with sheet mulching (also known by some as “lasagne gardening”) http://wp.me/p5JEJY-YZ so I thought we ought to re-visit and see how that worked. Sheet mulching is the layering of different kinds of compostable garden waste (sometimes with old newspapers or cardboard as well) on the surface of poor garden soil. The aim is to quickly add organic matter to the existing soil, improving drainage, water retention and fertility.

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I had several questions in my mind last fall when this experiment was carried out:

1. Will the cardboard decompose?
2. Is the “green” and “brown” balance right?
3. Will the raccoons and skunks churn it all up?
4. Will there be a crop of new weeds from the imported materials?
5. Will the cold Colorado winter simply stop any decomposition from taking place?
6. Will there just be a smelly slimy heap to remove next spring?
7. OR, will we have achieved that elixir of gardening – fertile, well-drained, moisture-retentive soil???

The experiment has been going on for some eight months now and these are the answers, so far:

1. YES. Some digging about at the base of the layers revealed no sign of cardboard except for a few stray bits of plastic tape that didn’t get removed when I broke down the cardboard boxes.
2. Probably YES. Though close inspection revealed that in some parts the grass clippings were laid too thick and would have done better if they’d been mixed in more with the dried leaves.
3. NO. Apart from a few little exploratory digs by some critters, the layers remained intact.
4. NO. Initially there was some germination from seeds (unidentified grass/cereal) which were in the chicken coop material I used, but these were easily pulled in the first couple of weeks. Since then not a single weed has appeared.
5. NO. Digging into the layers revealed pretty well composted good, brown material though not everywhere. Lots of worms too. Straw seems to have been the hardest to break down and is still recognizable in some places.
6. NO. See 5.
7. Well, MAYBE ….

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The native grey clay soil is still there beneath the sheet mulch

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Well on the way to being compost

There is no doubt that we now have deep layers of composted garden waste on our borders. The layers have not been totally absorbed into the soil below. They have shrunk in depth by a couple of inches which is probably mainly due to gravity and the reduction of air pockets. I accept that these borders may remain as “raised” borders for some time.

So, what happens next? I expect these sheet mulched borders to continue to decompose over the summer and, perhaps, by next spring will no longer be “raised”.

But I can’t wait until then to get new plants in.  Already, I have a planted a Japanese maple and some hellebores in one of the beds (both should benefit from the rich compost.  I dug holes in the compost layers, put in some native soil from elsewhere in the garden and planted and watered.

I was concerned that the compost itself would not hold the plant roots securely which is why I mixed in garden soil from elsewhere to give weight. It will also provide mineral nutrients that may not be present in the compost/mulch. Now, some six weeks later, the new plants are all well rooted and looking good.

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Japanese maple and hellebores just planted

So, is it worth doing? I’m giving the experiment a qualified “yes” at this stage.

I think it works for areas that have been neglected or are being cultivated for the first time. There is an initial effort in gathering the materials and building the sheet mulch layers, but then you just sit back and wait.

Does one big “hit” of compostable material work better than cumulative additions over the years? I don’t know. Time will tell as I compare these borders with others in the garden. Certainly, I got a lot more compost onto the borders than I could generate annually from my compost bins. (You don’t get a lot of kitchen waste from two people; and a modest-sized, young garden doesn’t produce much waste either.)

It might have been less work to simply go out and buy bags of compost from the garden center or big box store. That would have been expensive (my materials were all free). There are no regulations on what goes into bagged compost for retail sales.  At least I knew exactly what was in mine.

Aside from these thoughts, there has definitely been a great sense of satisfaction in doing the experiment.  It was interesting.  It was good exercise.  It was free.  I turned what other people thought was just rubbish messing up their yards into useful, re-vitalizing material for our garden and plants.

Anne Hughes/A Denver County Master Gardener