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Home | Mikl's Articles | Articles: Trees

Articles: Trees

Water-Wise Trees and Shrubs for Sunny Locations

XERISCAPE   TREES AND SHRUBS  for  SUN

Harlequin’s Gardens    303-939-9403  www.harlequinsgardens.com

 

Note: plants listed in bold are native to our region

TREES

Acer ginnala / Amur maple

Acer ginnala ‘Compacta’ / Dwf. Amur Maple

Acer grandidentatum / Bigtooth Maple

Acer negundo / Boxelder

Acer negundo ‘Sensation’ / ‘Sensation’ Boxelder, male selection

Acer tataricum ‘Hot Wings’ / Hot Wings Tatarian Maple

Aesculus glabra / Ohio Buckeye

Amelanchier utahensis / Utah Serviceberry

Catalpa speciosa / Western Catalpa

Celtis occidentalis / Western Hackberry

Celtis reticulata / Netleaf Hackberry

Crataegus ambigua / Russian Hawthorn

Crataegus crus-galli / Cockspur Hawthorn

Crataegus mollis / Downy Hawthorn

Crataegus monogyna / Singleseed Hawthorn

Crataegus phaenopyrum / Washington Hawthorn

Cupressus arizonica / Arizona Cypress

Gleditsia triacanthos inermis / Honeylocust

Gymnocladus dioica / Kentucky Coffeetree

Juniperus monosperma / One-seed Juniper

Juniperus scopulorum & selections / Rocky Mt. Juniper

Koelreuteria paniculata / Goldenrain Tree

Malus species / Flowering Crabapple selections

Morus alba / White Mulberry

Pinus aristata / Bristlecone Pine

Pinus cembroides edulis / Pinyon Pine

Pinus contorta v. latifolia / Lodgepole Pine

Pinus flexilis / Limber Pine

Pinus ponderosa / Ponderosa Pine

Prunus americana / American Wild Plum

Prunus padus / Mayday Tree, Bird Cherry

Prunus virginiana / Native Chokecherry

Prunus virginiana ‘Shubert’ / Canada Red Chokecherry

Prunus x virginiana ‘Sucker Punch’ / Non-suckering Chokecherry

Pseudotsuga menziesii v. glauca / Rocky Mt. Douglas Fir

Ptelea trifoliata / Wafer Ash, Hop Tree

Pyrus ussuriensis / Ussurian Pear

Quercus bicolor / Swamp White Oak

Quercus gambelii / Gambel Oak

Quercus macrocarpa / Bur Oak

Quercus muehlenbergii / Chinkapin Oak

Quercus undulata / Rocky Mt. Scrub Oak

Robinia neomexicana / New Mexico Locust

SHRUBS

Agave parryi ssp. neomexicana

Amelanchier alnifolia / Saskatoon Serviceberry

Amelanchier aln. ‘Regent’ / Regent Serviceberry

Amelanchier canadensis / Shadblow Serviceberry

Amelanchier laevis / Allegheny Serviceberry

Amorpha canescens / Great Plains Leadplant

Amorpha nana / Dwarf Leadplant

Artemisia cana / Silver Sagebrush

Artemisia filifolia / Sand Sagebrush

Artemisia tridentata / Tall Western Sagebrush

Artemisia versicolor (canescens) / Seafoam Sage

Atriplex canescens / Four Wing Saltbush

Atriplex confertifolia / Spiny Saltbush

Buddleia alternifolia ‘Argentea” / Silver Butterfly Bush

Buddleia dav. nanhoensis cultivars / Compact Butterfly Bush

Buddleia davidii cultivars / Butterfly Bush

Caragana arborescens / Siberian Peashrub

Caragana pygmaea / Pygmy Peashrub

Caryopteris x clandonensis cultivars / Blue Mist Spirea

Ceanothus fendleri / Mountain Lilac

Ceratoides lantana / Winterfat

Cercocarpus brevifolius / Little-flowered Mt. Mahogany

Cercocarpus intricatus / Littleleaf Mountain Mahogany

Cercocarpus ledifolius / Curl-leaf Mountain Mahogany

Cercocarpus montanus / Common Mountain Mahogany

Chamaebatieria millefolium / Fernbush

Chrysothamnus n. ssp. graveolens / Tall Grn. Rabbitbrush

Chrysothamnus naus. ssp. albicaulis / Tall Blue Rabbitbrush

Chrysothamnus naus. ssp. nauseosus / Dwf. Blue Rabbitbrush

Chrysothamnus viscidiflorus / Dwf. Grn. Rabbitbrush

Cotinus coggygria / Smoke Tree

Cotinus coggygria ‘Royal Purple’ / Royal Purple Smoke Tree

Cotinus x ‘Grace / ‘Grace’ Smoketree

Cotoneaster divaricatus / Spreading Cotoneaster

Cotoneaster lucidus / Peking Cotoneaster

Cotoneaster multiflora / Big-flowered Cotoneaster

Cowania mexicana (Purshia stansburyana)  / Cliffrose

Cytissus purgans ‘Spanish Gold’ / Andora Broom

Cytissus scoparius ‘Moonlight’ / Moonlight Broom

Ephedra americana / American Ephedra

Ephedra viridis / Mormon Tea

Fallugia paradoxa / Apache Plume

Forestiera neomexicana / New Mexico Privet

Genista lydia / Lydian Broom, Dwarf Broom

Genista tinctoria / Woadwaxen

Hesperaloe parviflora / Red Yucca

Hippophae rhamnoides / Sea Buckthorn

Holodiscus dumosus / Rock Spirea

Ligustrum vulgare ‘Cheyenne’ / ‘Cheyenne’ Privet

Ligustrum vulgare ‘Lodense’ / Lodense Privet

Lonicera k. v. floribunda ‘Blue Velvet’ / Blue Velvet Honeysuckle

Lonicera syringantha v. wolfii / Tiny Trumpet Honeysuckle

Lonicera tatarica selections / Shrub Honeysuckle

Mahonia aqu. Compactum / Compact Oregon Grapeholly

Mahonia aquifolium / Oregon Grapeholly

Mahonia fremontii / Fremont’s Mahonia

Mahonia haematocarpa / Desert Holly

Opuntia species / Cholla Cactus

Perovskia atriplicifolia / Russian Sage

Philadelphus lewisii / Lewis Mockorange

Physocarpus opulifolius cultivars / Ninebark

Juniperus communus/Common Juniper selections

Prunus besseyi / Western Sandcherry

Prunus besseyi ‘Pawnee Buttes’ / Pawnee Buttes Sandcherry

Prunus besseyi ‘Boulder Weeping’ / Boulder Weeping Sandcherry

Prunus tenella / Dwarf Russian Almond

Purshia tridentata / Antelope Bitterbrush

Pyracantha coccinea / Firethorn

Rhamnus smithii / Smith’s Buckthorn

Rhus aromatica / Fragrant Sumac

Rhus glabra / Smooth Sumac

Rhus glabra v. cismontana / Rocky Mt. Sumac

Rhus trilobata / Threeleaf Sumac

Rhus typhina / Staghorn Sumac

Rhus typhina laciniata / Cutleaf Staghorn Sumac

Ribes aureum / Native Golden Currant

Ribes cereum / Wax Currant

Ribes odoratum / Golden Currant

Robinia neomexicana / New Mexico Locust

Rosa ‘Alba Maxima’

Rosa ‘Alba semi-plena’

Rosa ‘Alba Suaveolens’

Rosa ‘Felicite Parmentier’

Rosa ‘Fruhlingsgold’

Rosa ‘Golden Wings’

Rosa ‘Harison’s Yellow

Rosa ‘Henry Kelsey’

Rosa ‘John Cabot’

Rosa ‘John Davis’

Rosa ‘Konigen von Danemark’

Rosa ‘Lawrence Johnston’

Rosa ‘Maiden’s Blush’

Rosa “Banshee”

Rosa arvensis

Rosa ‘Complicata’

Rosa eglanteria / Sweetbriar

Rosa foet. Persiana / Persian Yellow Rose

Rosa foetida bicolor / Austrian Copper Rose

Rosa glauca (rubrifolia) / Redleaf Rose

Rosa hugonis / Father Hugo’s Rose

Rosa woodsii / Wood’s Rose

Rosmarinus officinalis ‘Arp’ / Arp Rosemary

Shepherdia argentea / Silver Buffaloberry

Robinia neomexicana / New Mexico Locust

Spiraea ‘Cheyenne Snowmound’

Spiraea jap. ‘Goldflame’ / Goldflame Spirea

Syringa patula ‘Miss Kim’ / Miss Kim Dwf. Korean Lilac

Syringa prestoniae cultivars / Canadian Lilacs

Syringa vulgaris cultivars / Common Lilacs

Yucca baccata / Banana Yucca

Yucca filamentosa / Adam’s Needle

Yucca glauca / Native Soapweed, Narrowleaf Yucca

Yucca harrimanii / Harriman’s Dwf. Yucca

Patio Trees

Purple Smokebush

MIKL’s ‘MACRO BONSAI’ PATIO TREES FOR YOURSELF!

Every so often, one of the trees or shrubs we’ve grown or received from a grower displays interesting twists, bends, curves or dwarfing that suggest the character of Bonsai specimens, but much bigger. Mikl has been collecting and cultivating these ‘Macro Bonsai’ for quite a few years. We have some available for sale right now.

[Read More]

Dead or Alive?

Lace Bark Pine

by Mikl Brawner

As we enter June, most of our trees and shrubs have leafed out, but not all. Some have leaves only three quarters of the way up, and many broad-leafed evergreens are mostly brown. Should we cut them back or replace them? Let’s not, just yet.

[Read More]

Special Woody Plants

Jamesia americana – Waxflower

Mikl has assembled a collection of some of our most interesting, unusual and hard-to-find woody plants, many of which are just ready for sale now. These include some excellent native trees, shrubs and ground-covers, as well as particularly interesting and worthy non-natives that thrive in Colorado conditions. We’d like to share some descriptive profiles with you here.

[Read More]

Supporting our Colorado Trees

So they can support us!

Last Friday Denver Botanic Gardens hosted a day-long conference on Tree Diversity. This timely subject arises because of the importance of trees to the livability of our cities and suburbs and the degree to which the effects of Climate Change have already begun to affect our urban forest. Trees help cool everything from our gardens and patios and parking lots to our cities and our planet. With stresses like sudden, dramatic temperature changes, drought, and severe windstorms, plus the devastation wrought by the Emerald Ash Borer to our millions of Ash trees, it’s time to re-evaluate the limited palette of trees we’ve been planting for many decades, and investigate new, more resilient possibilities.  [Read More]

How Do We Manage Fireblight

Colorado is said to be the worst state in the US for fireblight, and 2018 was considered by many to be one of the worst years in Colorado. Fireblight is a serious disease affecting apples, crabapples, pears, Mountain Ash and hawthorn, and sometimes quince and pyracantha (supposedly up to 73 species of plants).[Read More]

Quaking Aspens

Leave them to the Mountains OR Plant them at Home?

Populus tremuloides or Quaking Aspen is not only one of the best-known native trees here in Colorado, but it is said to be the most widely distributed tree of North America. Its narrow, roughly pyramidal form is commonly 25’-30’ tall and 15’-20’ wide, although it can get much larger. The leaves are shiny, dark green above and light gray-green beneath which makes the tree shimmer in the breezes. Also its whitish trunk adds to its attractive architecture. Then in the fall the leaves can turn a rich golden yellow which look glorious on the tree and lovely on the ground. It has a suckering habit which inclines it to clumps and which has put aspen in the running for the world’s largest being.[Read More]

Bigtooth Maple

Bigtooth Maple, Acer grandidentatum, is native to the far southwest corner of Colorado in a place known as Sleeping Ute Mountain. It is common in canyons, northfacing slopes and along mountain streams in Utah, Wyoming and west Texas from 5000′ to 8000′. Although most often listed as a separate species, Bigtooth Maple is sometimes called Western Sugar Maple, therefore, a subspecies of Acer saccharum. Its other names are Canyon Maple and Wasatch Maple.[Read More]

Bur Oak

BUR OAK—QUERCUS MACROCARPA-MOSSY CUP OAK

One of the most successful oaks for Colorado is the Bur Oak. It is adaptable to our clay soils and tolerates our alkaline conditions better than most oaks. In harsh, droughty areas this tree can be a low shrub, but on rich, river-bottom land can get 170’ high and 6’-7’ in diameter; but most often grows 50’-70’ high. The trunk is often thick and short with deeply furrowed bark, and the stout branches often extend almost straight out making the tree as broad as tall. The leaves are deeply lobed only in the bottom half and these lobes are rounded not pointed as with many other oaks. The acorns are distinctive in that there is a mossy fringe around the cap. The overall effect can be quite grand and sculptural, sometimes like a Chinese painting. The short taproot is surrounded by a massive root system which is strongly competitive. This is why old specimens often are standing alone.[Read More]

Catalpa

Western (Northern) Catalpa- Catalpa speciosa

It is surprising that a tree that looks so different from the other Colorado-adapted trees, is so successful. What stands out immediately are the huge leaves which can be 3”x 6” or even 6” x “12” and are heart-shaped. And in June, this large shade tree blooms exquisite, ruffled, bell-like, white, fragrant flowers with yellow and purplish coloration .And in the fall the passerby might be surprised to see the long thin pods 10”- 18” long.[Read More]

Champion Trees Show More Possibilities

Growing trees in Colorado, especially big shade trees, can be very challenging. Few of the specimens in our community “forests” are native to Colorado, and areas where big trees are abundant are often so different from our conditions that those trees do not adapt well here. Some of the difficulties trees face here are: alkaline soils, nutrient-poor and shallow soils, low humidity, hot and drying winter sun, strong winds, untimely wet snows in spring and fall, rapidly changing temperatures, and low rainfall. Add to these the confining root zones in which many trees are growing in urban environments, and it is easy to understand why our trees are often stressed, subject to borer and fungus problems, broken and short-lived.[Read More]

Kentucky Coffee Tree – Gymnocladus dioica

This member of the pea family (Fabaceae) can get 50’-60’ high and 30’-40’ wide, though most that I’ve seen in Colorado are under 45’. Nearly everybody thinks of this tree as interesting or picturesque.The branching is more open than most trees and the bark is gray to dark brown, rough and deeply ridged even on small branches. The leaves are  bluish-green and somewhat tropical-looking being double compound, each one 18”-24” long and forked with small leaflets alternating on the stem. Fall color is yellow. As the species name implies, this tree is dioecious, having the male and female flowers on separate trees. The flowers are greenish-white, supposedly fragrant and not conspicuous. On the female trees, tough, leathery seed pods follow that are 4”-6” long and 1 1/4”-2” wide. These hang on after the leaves fall and into the winter.[Read More]

Hackberry

Common Hackberry  (Celtis occidentalis)

Why would anybody be interested in a tree that is just the common variety? In this case, we Coloradoans can be very interested because “common” means it will grow just about anywhere. In our harsh country that provides a good living for people planting and replanting and pruning and re-pruning trees, the Common Hackberry is somewhat of a relief. It will grow to 7000’. Our 25 below zero winters do not bother it as it is hardy to zone 2, which helps a lot in adjusting to our sudden warm-to-cold swings. It is also not picky about soils, tolerating both acidic and our usual alkaline conditions; rocky is fine, heavy clay is OK; it really likes rich, moist, but grows right along in poor, dry, windy, polluted cities. [Read More]

How to Plant a Tree

Planting a tree puts us in touch with one of the most essential parts of a tree that is often overlooked—the roots. When a seed germinates, the first part to develop is the root. The seed has stored nutrients, but if the plant is to live, it must immediately make a relationship with the nourishment of the earth. Then it can make the sprout that pushes into the sunlight to start photosynthesizing. So the first matter of importance in planting a tree is to honor its roots—their condition, their future environment and their nourishment.[Read More]

Interview with Alex Shigo

Alex Shigo is a world-renowned authority in arboriculture, the science of trees. His delving curiosity and sharp scientific analyses carried him beneath the bark into a realm previously little understood. He worked 26 years for the US Forest Service investigating decay in trees, and through the process of dissecting over 15,000 trees with a chainsaw, he has uncovered much valuable information about tree structures and tree systems that have revolutionized the practice of tree care. As he puts it in the preface to his book Tree Pruning, “A major problem throughout the history of tree pruning has been the scant attention given to pruning as it affects the health of trees, while great attention has been given to pruning as it affects the desires of man.” Even though he is busy writing, giving workshops and talks and doing consulting, he agreed to answer some pressing questions for The Colorado Gardener.[Read More]

Mountain Ash

European Mt. Ash (Sorbus aucuparia)

This is surely one of my favorite ornamental trees for the front range which can be used up to 8000’.It is an upright oval tree spreading with age 25’-30’ tall aned 15’-25’ wide. If cared for, it will be attractive throughout the season. The bark is a shiny, orangy-brown. The serrated, compound leaves are dark green and in the fall turn yellow and reddish-gold. The clusters of flowers are white, blooming in spring with a peculiar fragrance that some people appreciate more when they’re gone. Clusters of red-orange berry-like fruit follow which color the tree through the fall, accenting the orangy leaf colors. These fruits are greatly loved by the birds and are in fact edible for people. They are known as Rowan berries and are used in Europe in making a brandy. In ancient times the Rowan tree, also know as the Quickbeam, was greatly revered by the Druids and used against lightning and witches’charms. The berries were considered extremely valuable having the “sustaining value of nine meals”, healing the wounded and giving a man the strength of ten men. I had to try this, of course, and found I couldn’t eat even 10 berries. Later I learned they need to “blet” or shelf-ripened. The birds do spread these around, and Mt. Ash seedlings are not uncommon.[Read More]

Pinyon Pine – Pinus edulis (Pinus cembroides edulis)

The Pinyon Pine has several advantages over other evergreen trees in a Colorado landscape. For one thing, its size doesn’t consume so much horizontal space. Compare the modest mature Pinyon at 10’-15’ in diameter with Austrian or Ponderosa at 25’-35’ diameter or Blue Spruce at 30’-40’ diameter. A few of these “average” sized evergreens look innocent when freshly planted, but who hasn’t seen them blocking sidewalks and doorways, tearing off gutters and shading solar collectors and windows in the winter? The Pinyon with its gently rounded top only gets 12’-20’ high, which suffices for many screening needs and still leaves the view. If it isn’t crowded, it stays branched to the ground with dense foliage of short, medium green to gray-green needles, two to a bundle. The cones are small 1 1/2”-2” long, brown to reddish-brown, which open to a rosette form and in the wild yield Pinyon “nuts”. These seeds are good-tasting and oily, with a piney flavor much appreciated by birds, animals and humans. They are also nutritious, being higher in protein and carbohydrates than pecans, but lower in fat. For some reason , these “nuts” are unlikely to develop in small urban plantings.[Read More]

Redbud

One of the most beautiful ornamental trees is the Eastern Redbud, Cercis canadensis. It is a native of the eastern and southern U.S. and has “naturalized” in older Boulder neighborhoods. It’s most distinctive feature is its reddish purple buds  followed by intense purplish-pink pea-like flowers in late April before the leaves come out. This wondrous and heart-warming display is greatly appreciated so early in spring but cannot be counted on if winters are too harsh.

It is a smaller tree 20’-25’ high and wide with attractive bark and heart-shaped leaves which are shiny and purplish when young. Fall color is yellow. It is said to be hardy  to zone 4 and we have many fine specimens in Boulder.[Read More]

Small Trees for Eastern or Northern Exposures

Shade trees 40’-60’ high and wide are great on the south and west sides of our houses and offices. They reduce temperatures and reduce cooling costs in the warm months, but they are not always appropriate. We don’t want dense shade where we grow most xeriscapes, rock gardens, herb gardens, most natives and many perennials. In addition, there is no need for big shade trees on the north side, and the morning sun is usually welcome on the east side of our houses and workplaces. And many plants prosper in morning sun and afternoon shade. It is also significant that a 20’ tree costs far less to have pruned than a 40’ tree. So it seems to me we should be growing small trees under 30’ tall on the east and north sides of our buildings.[Read More]

Stressed Trees: How to prune and care for them

Trees have it hard in Colorado. If it’s not the shallow and lean topsoil, it’s the low rainfall and low humidity, or it’s the heavy wet late spring or early fall snows, or like last November, it’s the dramatic temperature changes. After a warm and beautiful fall without a killing frost until November 11, we experienced a 77 degree drop in temperature between November 10 and November 12. This was one of the three largest temperature drops ever recorded in the Denver area, the other two were in December 2013 and January 2014.[Read More]

Supporting Trees in Colorado

Trees do a lot for us humans, so we shouldn’t forget to give them some support. When I look at the treeless ten acre lot next to our nursery, or when I see an old photo of the CU campus with bare land around Old Main, I remember why we can’t take trees for granted in Colorado. Trees really have it hard here, but there are things we can do to help them survive and thrive.[Read More]

Tree Roots 1: The hidden support system

The roots are the hidden support system of our giant plants, the trees. They anchor their woody trunks to the ground, store food and bring in water, nutrients and oxygen. In this article I will discuss what is going on down there. In the next issue I will discuss more practical applications of this understanding.  

Far less is known about tree roots than about the trunk, branches and leaves. This is understandable since the roots are hidden from our view, and once you dig them up, they are no longer what they were. We are awed by the massive trees swaying over our houses and streets, but usually we give little thought to what is going on under the surface. However, when spring thawing is followed by powerful winds and we see an 80’ spruce toppled over with its roots in the air, which are only 9” deep; that gets us thinking.[Read More]

Tree Roots 2: The hidden support system part II

What would we do without trees? What structures could we invent and construct that would hang over our houses and offices, providing shade and cooler temperatures? Such a structure would have to hold up under 80 mph winds and heavy wet snows, and would have to retract in the winter to let in light. Trees provide these values and much more, giving off oxygen, providing housing for birds, and protection for understory plants. Thus it is very important to take good care of our trees, and the most fundamental level of that care must be directed to the roots.[Read More]