Bur Oak (Quercus macrocarpa) is a majestic, slow-growing tree reaching 60 to 70’ in height and spread, and is typically very long-lived (think 200, 300+ years!). It’s the sort of tree you plant for the benefit of the generations to come. Many oak species don’t thrive in Colorado’s alkaline soils, but Bur Oak is a happy exception. It is also drought-tolerant once established, even in dry clay, and can handle city conditions quite well. Bur Oak’s strong wood and strong, almost right-angled branch connections resist breakage in wind and snow. [Read More]
Bur Oak, the ‘Smart Tree’
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]
Beautiful Autumn Colors
We are all enjoying and appreciating the exceptional fall colors this year. The yellows are especially rich, and the reds are especially vivid. What is going on when the green leaves turn colors and why are the colors so spectacular this year?
We know that the green color of the leaves comes from the pigment chlorophyll that makes it possible for plants to capture energy from sunlight and use it to make the sugars that feed the whole planet. When the long days of summer get shorter and shorter, highlighted by the fall equinox this year on September 22, the plants get less and less sunlight and less and less energy to make chlorophyll. When leaves contain less chlorophyll, other pigments become more dominant. [Read More]
Woody Plant Die-back and Pruning
October 2020 went from record high temperatures in the 80s to record lows, 19 degrees by October 25. May 2021 also made some shocking temperature changes. These rapid and dramatic changes can cause woody plants to die back, lose branches or die completely.
Mikl has been waiting and waiting before pruning this spring, because sometimes our woody plants can leaf out very late. Here is a way to tell when to prune: [Read More]
TREES – 2022 Newsletter
The TREES we sell are smaller than ball & burlap trees that are dug in the field, leaving at least 75% of their roots in the ground. Ours are grown in a container so they have a complete root system and begin growing immediately and are not stressed. Here is a sample of some of our selection.
Very tough and xeric, grows 15’ high and wide, white flowers and red berries, loves Colorado conditions!
ROCKY MT. MAPLE
Native to our foothills, likes to grow in the protection of other trees, red fall color, 10’-15’.
GAMBEL OAK and WAVYLEAF OAK
Both natives that grow 10’-15’, with little water and poor soil, support birds.
Good shade tree to replace an ash, a fast-growing hardwood, the most drought tolerant shade tree.
The hardiest mulberry, 25-30’ tall and wide, very xeric, white fruit is tasty and does not stain. Brings Western Tanagers, Orioles to your garden!
GOLDEN RAIN TREE
25′ xeric tree with golden flowers in July, orange lantern-like pods, orange fall color, seeds abundantly.
Native, suckering tree to 15′-25′ with white flowers, edible fruit; great for birds and butterflies.
SUCKER PUNCH CHOKECHERRY
Leaves start green then turn red all season, non-suckering, white flowers, berries.
SILVER BUFFALOBERRY (Shepherdia)
10′ native small tree with edible red fruit on female plants,, silver leaves, very xeric, few thorns.
MAYDAY TREE (Prunus padus)
20′-30′ with clusters of white flowers, then bird fruit, fast screen.
40′-50′ with vertical habit, fragrant orchid-like flowers, huge heart-shaped leaves, 12″ beans, xeric and special.
20′-30′ hardy evergreen, blue foliage is fragrant, not scratchy, quite fast growing, bird favorite.
Plus, Honeylocust, Crab Apples, Silver Maple, Bur Oak, Thornless Cockspur Hawthorn, Aspen, Ptelea, Kentucky Coffee Tree, Ohio Buckeye, Autumn Brilliance Serviceberry, Hot Wings Maple, Alder, Native Birch, Bigtooth Maple, and More!
We have to suck carbon out of the atmosphere naturally — by planting trillions of trees…
– Senior Climate Scientist Brenda Ekwurzel
HOME-GROWN FRUIT – 2022 Newsletter
CURRANTS, GOOSEBERRIES, BLACKBERRIES, RASPBERRIES
One of our specialties is fruiting plants that are adapted to Colorado conditions. All the apples we carry are resistant to fireblight and good tasting. And the cherries we sell are all proven successful in Colorado. Our grapes are the hardiest of any you will find, delicious fresh, in juice and a few are good for wine. And we have productive & good tasting currants, gooseberries, blackberries, strawberries, raspberries including: [Read More]
It’s Okay to Prune Now
All spring we have been advising you not to prune out branches without leaves yet. After last October’s flash freeze and this March’s freeze of the new leaves, it was important to give shrubs, trees and roses time for a second set of leaves to come out before removing wood. By now we should be seeing new green leaves forming if the wood is still alive.
So now we can prune away any branches that are not leafing out. Do cut back to a leafed-out branch or sprout; don’t leave a stub. Some evergreens may still be looking very brown. Look closely to see if tiny leaves are forming amongst the brown ones. Use a broom or gloved-hand to brush away dead needles. If you start removing branches from a conifer it may never look good again, so if you see any green, give it a chance. [Read More]
Pruning Woody Plants in the Spring
Don’t be in a hurry to prune dead branches on woody plants this spring! Last fall we had warm weather followed by a fast-deep freeze, and this spring we had an 11-degree freeze after some leaves were out. Some branches and some whole shrubs may have died, but most will put out new leaves. So, it is best to wait another couple of weeks before pruning.
To know for sure if a branch is dead, try the old fingernail test: scratch a little bark on a smaller branch; if the wood under the bark is green, the branch is alive, if brown, it is dead. Also, wrinkled bark shows it is dead.[Read More]
Shrub and Tree Recovery Fertilizers and Mineral Supplements
AGE OLD ORGANICS DRY BLENDS
Grow Formula: 8-4-1. a naturally based, high nitrogen blend of nutrients, including 1% calcium, which are slowly converted by soil microbes into plant available forms. Grow Formula is an excellent nutrient addition to potting mixes or soils and can be used as a top dressing on existing gardens and lawns.
Support Tree and Shrub Recovery
The ancient proverb “March winds and April showers bring forth May flowers” could be revised for Colorado as “March and April heavy snow, freezing temps, and strong winds bring forth May flowers”! And this year was no exception. Two recent cold snaps with temperatures reaching lows of 3 degrees F in our neighborhood, snows up to 36” in the foothills, and winds that will bring down any weak tree branches, wreaked havoc and impacted flower and fruit productivity. So now it’s time to help support our shrubs and trees to recover.
The most influential factor in this process is soil biology, which is activated by warmth in the soil. [Read More]
Native Plants We Often Have for Sale
These are native plants that we often have for sale. Availability does change every year, but we grow and buy a wide variety of natives because they are so successful in our gardens.
KEY: t = tree, s = shrub, v = vine, gr = grass, gc = ground cover, p = perennial,
b = biennial, a = annual
Abronia fragrans (Sand Verbena) (p)
Acer glabrum (Rocky Mt. Maple) (t)
Acer grandidentatum (Bigtooth Maple) (t)
Achillea lanulosa (Native White Yarrow) (p)
Agastache cana (Hummingbird Mint) (p)
Agave parryi (Hardy Century Plant) (s)[Read More]
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, 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—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]
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]
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]
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]
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]
Pruning Article for Boulder Home and Garden
For many people, pruning is the maintenance job they most fear and dread. And it is good to be wary, because a tree that is badly pruned can dominate a landscape with its ugliness for years, can be more prone to breakage and disease, and can have a much shorter life.
Tree and shrub pruning have four basic aspects: the practical or aesthetic interests of the owners, the biology of how trees “heal”, the physics of what makes a branch strong or weak, and the art of how to create beautiful forms.[Read More]