How can we deal with all the bugs and diseases without using toxic poisons, and how can our gardens really produce without high-powered chemical fertilizers? Many people wanting to garden sustainably are asking these questions. And it is not easy to find the answers, partly because the answers are not simple. I want to admit this up front, but don’t be scared off, because it’s not that hard to garden sustainably once you get the hang of it. However you must know that you can’t just exchange a slam-bam chemical approach for a slam-bam sustainable approach.
In February 2000 President Clinton established the National Invasive Species Council. Agriculture secretary Dan Glickman, Commerce Secretary William Daley and Interior Secretary Bruce Babbitt were asked to work together on a plan to minimize the economic, ecological and human health impact of invasive plants and animals not native to the US. The executive order on Invasive Species directs federal agencies to prevent the introduction of invasive species, to control populations of such species in a cost-effective and environmentally sound manner, to monitor populations, restore native species, conduct research and promote public education on invasive species.
One of the hot subjects in horticulture these days is the issue of the invasiveness of introduced plants. Since they did not evolve here, they lack natural enemies, and whereas most are harmless, some have engulfed vast areas of wilderness, national forests, range and farm lands. This has led some people to campaign for “natives only” and others to attack the introduction of new plants as an ecological nightmare. In response to these attacks some in the plant industry have dismissed these fears as invalid over-reactions. As Colorado gardeners, most of us can be both excited by new plant introductions that are well-adapted to Colorado conditions, and feel very protective of our natural ecosystem and our native plants. In a series of articles, we hope to uncover some truths regarding these issues and to educate ourselves about how to work with this situation in a constructive manner.
In general, shade trees are not very tolerant of drought. Some people have gotten the idea that since trees have big root systems, they are less vulnerable to dry conditions. Unfortunately this is not true. Truly xeric trees that are native to arid regions are usually small, more like big shrubs. Even in our semi-arid region, photos from a hundred years ago, show very open and unshaded areas where we now have our urban forests. Most shade trees come from forested areas with much more rainfall and deeper, richer soils. On top of that, our trees are often made to grow in very confined areas in heavily compacted soils. So even under normal circumstances, big trees have a hard life here in Colorado. Therefore, during a drought, we must take extra care to make sure they survive by deeply watering at least once a month. If you multiply the diameter of a tree in inches times 10, you will get the recommended gallons of water required per watering. This water should be applied, not next to the trunk, but in a wide band around the drip line. Your best chances of establishing a tree during water restrictions are to:
In the last issue I discussed the easy broadleaf evergreens for Colorado and this time we will go into the difficult ones. Many people have killed or had poor success with rhododendrons, hollies, azaleas and daphnes etc. so it is good to understand these plants further. Unfortunately in my sunny, low-water gardens, I have had little experience with them so I went to two people who have plenty of experience, Don Zaun and Allan Taylor.
It is widely known that nitrogen is essential for plants. It is a major component of amino acids, DNA and chlorophyll. It is necessary for photosynthesis, the alchemical process of turning sunlight, carbon dioxide, minerals and water into oxygen and sugars that is the food that feeds life on earth. In Colorado, most of our soils are deficient in nitrogen.
But too much nitrogen can be a problem, especially high nitrogen chemical fertilizers. Bill McKibben, author of The Art of Balancing Soil Nutrients states, “Although all plant nutrients are critical, none seem to produce such quick and dramatic effect on plant growth as nitrogen does. It is because of this reason that nitrogen has been over-used and abused.” A 20%-30% nitrogen fertilizer can make a spring lawn turn bright green practically overnight, and can make plants in a greenhouse or garden grow and look mature really fast. So what’s the problem?
Flood recovery is not a problem most of us have had to deal with before so we can only try to solve the problems individually and make adjustments in the future.
The main problems seem to be:
1) Soil washed away-erosion
2) Soil dumped on top of plants, trees and existing soil
3) Plants washed away
4) Weed seeds deposited on the soil 5) manure and sewage and unknown contaminants deposited on the land
In the winter when the deciduous plants have dropped their leaves, the evergreens really stand out. If we go for a walk, especially in the older neighborhoods, what evergreens do we see? The greatest numbers are spruces, firs, pines and junipers. In general these conifers with their narrow needles or scales are adapted to our cold temperatures, strong winds and sunny winter days. But there are other woody evergreens to be seen in Colorado neighborhoods: the broad-leaf evergreens. In general their wide leaves transpire more and are more prone to desiccation in our drying conditions; however by choosing the right plants and siting them in their right places, we can enjoy these less popular but deeply satisfying winter-green shrubs and vines. In this article I will discuss the easy broad-leaf evergreens for Colorado and in the April issue we will talk about the difficult ones.
Many Colorado gardeners have been frustrated in their attempts to grow climbing roses. The main problem seems to be that the tall canes die back and though they may bloom, they look like shrubs, not climbers. We are green with envy of the European and Californian gardens with roses cascading over and festooning pillars, walls and bowers. Why can’t we achieve this? I think we can, but not without a very discriminating approach. First of all we must realize that our cold temperatures and especially the rapid cold-hot-cold changes, and our drying winter winds are death to all but the hardiest rose canes.
Henry Kelsey (1984 Kordesii cross) is an Explorer Series rose from Ag. Canada that is hardy to Zone 3 and is considered by many to be the best red-flowered climber for cold climates. It is very vigorous and grows strongly even in lean soils. Whereas it can be grown as a low arching shrub to 4’, it excels as a short climber to 8’-10’ and looks especially good trained down a split-rail fence. The flowers are semi-double with prominent golden stamens, opening a luscious deep red and fading to a pinker medium red. The fragrance is light but pleasant and the clusters of flowers repeat from June until frost. Where I have grown it in a very low water area over the last five years it has performed well and has not died back on the trellis, but repeat flowering is intermittent rather than continuous. One of the truths of xeriscape is that not all plants that grow well on low water, flower as well. Sometimes just one or two deep waterings during bloom time will make a big difference in flower production.
Fortunately, there are many choices of drought-tolerant shrubs. And not only can they tolerate drier conditions, the fact that they are taller than most perennials and groundcovers helps them to compete better with weeds, giving them a greater survival potential in untamed, harsh or more industrial locations. In native ecosystems, it is often the shrubs that begin to pioneer a barren ground, and the shade and wind-protection they create, gives more favorable microclimates for other plants to germinate and find a home. There are many fine non-native shrubs for xeriscapes, but in this article, I am mostly going to describe some of my favorite native shrubs for drier conditions.
The best chance of having delphiniums that don’t blow over is to plant them on the east side of the house or garage where they get good early day sun and where they are protected from the west wind. Next is to put in varieties that are not so tall and top-heavy. Here are a few varieties that fit that bill.
Normally when we think of fungi relating to plants, what comes to mind is infection and disease: powdery mildew, blackspot, slime flux and canker; Oh, NO!! However there is a growing awareness of the far more extensive benefits that fungi contribute to our world. Decomposing fungi are primary agents in the composting process which to us recyclers is the magic of turning garbage into gold. Not only do our plants love the rich humus and organic matter, but pesticides and herbicides are also broken down. Much of the body of soil itself is made up of fungi, especially loamy, well-aerated soil. And then there are the symbiotic fungi, the ones forming mutually beneficial relationships with plants. These associations of absorbing roots with fungal mycelium are known as mycorrhizae, from “mycor”- fungus and “rhiza”-root. Even though these beneficial relationships were discovered in 1885, it is not widely known today that 95 % of all plants on earth intermingle their roots with mycorrhizal fungi.
GMO has become a dirty word and a symbol for Monsanto’s corporate control over our health. Genetically modified organisms (GMOs) are the result of slamming DNA (genetic material) from one organism with the DNA of another, yielding altered characteristics. The bizarre results are discarded and the profitable ones, like being unaffected by the herbicide Roundup, are reproduced. Current approved GMO crops include Roundup Ready corn, soybeans, canola and this year, sweet corn. The advantage with these crops is that a farmer can have easy perfect weed control, by spraying the whole field with the herbicide Roundup, killing the weeds but not the crop.
There are many varieties of Dianthus that are successful here in Colorado. Since there are about 250 species and 30,000 registered names of Dianthus, this article is only going to cover a fraction of the subject. Most of the species dianthus come from the Mediterranean region, the Balkan Peninsula and Asia Minor. They grow mostly in sunny, dry, well-drained soils among rocks or with short grasses in meadows, and most are happy in a more alkaline environment. These are reasons why they are often well-adapted to our natural conditions. Many varieties are easy for us to grow, and they satisfy us in many ways because some 1) are very fragrant 2) are excellent cut flowers 3) are durable, evergreen ground covers 4) are good in borders, cottage gardens, rock gardens and xeriscape gardens.
Here’s a shrub that won’t grow over the living room windows, spread half-way across the driveway or send suckers up in the perennial border. It stays a compact 2’-3’ high and a little wider. It’s name comes from its spring leaf coloration which begins a russet or bronze-red mixed with yellow, changing to yellow-green and then green. The flowers are pinkish and bloom for a long time. Then again in the fall the spring leaf colors return to a golden copper-orange. This variety is very heat tolerant and has been successful in my xeriscape garden for 7-8 years. Occasional winter dieback has been slight and easily sheared off with hedge clippers. I also use the hedge clippers to remove the spent flowers after blooming.
In the last issue I mentioned that Dianthus in general like sunny and well-drained conditions, and that because they cross-pollinate freely, you can only be sure you are getting a named variety like ‘Pike’s Pink’ if it has been propagated by cuttings.It is also significant that the strong fragrance common to many of the Dianthus tribe is not only pleasing to us humans, it is very attracting to many butterflies.
Here are a few more varieties that do well in our area:
At the end of last season I wrote about how to succeed with climbing roses in Colorado. Besides winter watering and careful siting out of the worst wind, the most important factor is the choice of very cold hardy roses that are grown on their own roots. The books may say we are zone 5 but when the temperature drops from 50 at noon to 5 at two a.m., we better hope our rose is zone 4 or even zone 3 hardy. With climbers this is even more true because if the canes die back to two feet the rose may still bloom but it won’t function as a climber that year. Here are a few of the toughest and most cold-hardy climbing roses for Colorado.
Lilacs were brought to America by the earliest settlers and have been very popular landscape shrubs ever since for good reasons. Lilacs are tough, drought tolerant, usually healthy, long-lived, have masses of beautiful flowers and most of them have a delicious fragrance. In dry Colorado air, you have to stick your nose in most flowers to get the smell, but lilacs carry their rich perfume for quite a distance. Like most young boys, I was more interested in bugs than flowers, but my earliest memory of a flower was lying on a grassy hill next to a lilac hedge in full bloom, soothing my spring fever in the sweet, heady fragrance of the common lilac. This powerful aroma is one of the main attractions to lilac and one of the reasons why people forgive other garden qualities like the huge size and habit of suckering.
In fact, the tendency to sucker and the ease of transplanting are primary reasons for the rapid spread of lilacs across America. By the 1650s, lilacs were growing all over the colonies, and later they were carried west by the pioneers. I recently pruned some lilacs that were planted by miners in the rocky foothills above Boulder. I can just imagine some rough traveler, burning with gold fever and the Colorado sun, sharing his canteen with a lilac sucker.
Lilacs are natives of colder regions of southeastern Europe and northern regions of China and Korea. What we call Common Lilac, Syringa vulgaris, came from Romania, Yugoslavia and Bulgaria. The species comes in purple and white, is long blooming and is one of the most fragrant. It will grow to 12—15′ and can spread to make wide clumps, making a good screen. Because they are native to limestone areas, they prosper in our alkaline soils. And their hardiness makes them enduring in Colorado: books say to zone 4, but local growers say zone 3 or even 2 and to 10,000′.
Another reason lilacs are so popular is that they have been hybridized so much that there are many colors and forms to choose from. From Syringa vulgaris were bred at least 1500 cultivars. Starting in the 1880s, Victor Lemoine of France began selecting and hybridizing lilacs. It was a family enterprise with Victor as the leader, Madame Lemoine climbing ladders to do the actual cross pollinating and their son Emile taking over the business. They achieved 214 successful varieties, and both Victor and Madame Lemoine have great lilacs names after them. These are what we now call the French Lilacs. Since Lemoine, there have been many lilac breeders, several from the United States including Father John Fiala who wrote the great reference Lilacs: The Genus Syringa.
Some successful Syringa vulgaris cultivars available in our area are: ‘Albert Holden’ has deep violet blossoms with a silver reverse and good fragrance and grows to only 7—8′. ‘Arch McKean’ which has magenta flowers and very little suckering, growing to 7—8′. ‘Beauty of Moscow’ (‘Krasavitsa Moskvy’) with double white fragrant blossoms growing to 10—12′.(“one of the finest lilacs in commerce.” Fiala); ‘President Grevy’ has excellent double blue flowers in immense panicles.
‘Edith Cavell’ is rated “excellent” with double white, very showy flowers. ‘Monge’ is a single deep purple that is “outstandingly showy” and grows to 10—12′. This one is thriving at the neglected Cheyenne Station. ‘Sensation’ is very striking with its purple flowers edged with white. ‘Marie Frances’ has true soft pink flowers that are very fragrant.
Besides Syringa vulgaris, there are 22 other species, all from Asia. Some of these are not garden worthy, several were used in breeding great new hybrids and some make good shrubs in themselves. Syringa laciniata is sometimes available. It is quite beautiful with its cut leaves and its lavender blossoms. It is an annual bloomer, is long-flowering and suckers very little.
Syringa meyeri is compact and the variety ‘Palabin’ is available locally. It grows to 5′, needs little pruning and likes loose soils. It has deep purple buds and lavender-blue flowers and succeeds in dry conditions.
Syringa microphylla ‘Superba’ has small leaves, as its name implies. It is slow growing to 6—8′ and is wide spreading with small clusters of dark pink flowers that are sweetly fragrant. This is a lilac that will make a few blooms again in summer and fall. This is a real treat.
Syringa oblata is occasionally available and although it is an early bloomer, it is less susceptible to freezing than S. vulgaris and so is fairly reliable. The flowers are pale purple and the fall color is wine red. The variety dilatata is a superior form with very fragrant purple flowers and the variety ‘Cheyenne’ is extremely fragrant.
Syringa x hyacinthiflora is a cross between Syringa oblata and S. vulgaris. These hybrids bloom a week to 10 days before the French Vulgaris Hybrids. The fragrant flowers can be white, lavender or purple and the fall color is wine red. They are successful large, dense shrubs for Colorado, growing to 10—12′, and can be used as hedges since their leaves and flowers form all the way to the lower branches. They are hardy to 9000′. However since they bloom early, avoid planting them in a frost pocket or next to a tall wall or house where the flowers can be coaxed to open early only to be frozen. A few that are available locally are ‘Mount Baker’ with very fragrant, pure white flowers, ‘Assissippi’ which is the earliest with fragrant lavender flowers, and ‘Pocahontas’ with deep violet fragrant flowers.
Syringa patula is a late blooming species from the mountains of South Korea. The selection ‘Miss Kim’ is fabulous for its compact form and its very fragrant ice-blue-lavender flowers. It has burgundy fall color and prefers a well-drained soil.
Syringa x prestoniae are a series of hybrids from crossing Syringa villosa and S. reflexa. Isabella Preston was the Canadian hybridizer of these prolific bloomers. They flower about 10-14 days later than S. vulgaris and have a spicy “oriental” fragrance. They are very hardy to zone 2 and can grow to 9000′ or 10,000′. They do not sucker and so can be pruned into small multi-stemmed trees. Some varieties that are available locally are: ‘Isabella’ with lavender flowers, ‘James Macfarlane’ with pink flowers, ‘Miss Canada’ with deep pink flowers only growing to 6—9′ and ‘Minuet’ with purple flowers growing to 6—9′.
Another lilac species that is a favorite in Colorado is Syringa reticulata, the Japanese Tree Lilac. It grows to 15—5′, blooming with white flowers in very late spring. The variety ‘Ivory Silk’ has a more compact form and the same cinnamon-brown peeling bark. The fragrance is like privet, that is, not delicious. It is hardy to zone 4 and 6500′.
The best culture for lilacs is fertile, well-drained soil with plenty of organic matter in full sun. The Common Purple and Common White seem to do just fine in my lean gravelly soil with almost no organic matter, but for the hybrids, for longer bloom, bigger and more flowers higher fertility is necessary. Father Fiala says commercial fertilizer is no substitute for two year old manure and compost, because they provide tilth, hold moisture and feed the soil microorganisms. The worst conditions for lilacs are “wet feet”, shade and subsoil. If heavy wet clay is all there is, Father Fiala says to build a 3′ high mound with gravel, top soil, manure and compost; and plant at the top of the mound. Another option is to plant near the top of a slope; never near the bottom. Syringa vulgaris and its offspring are the most tolerant lilacs for heavy clay, but not if it is soggy.
The best pruning for lilacs is to remove the dead, broken and very old. Also take out many of the suckers, but leave the biggest ones if they aren’t too crowded. Once the shrub is mature, remove a fourth to a third of the oldest wood every year. And prune the tallest branches down 10%-20% to a side branch leading out. This should be done soon after blooming so next year’s buds are not removed.
When a lilac has not been blooming well or has gotten very old with little care, it can often be rejuvenated if the roots are sound. First scratch in some composted manure into the top 2″ of the soil, and then mulch 3″ deep. Then cut out the oldest canes, or if it has too much dead, cut the whole shrub to the ground in the early spring before it leafs out. This will either renew it or if the roots are rotten, it may not survive the operation. Do not cut a weak lilac to the ground in the summer, because that would likely kill it.
There is not universal agreement as to the value of dead-heading the spent flowers, but Father Fiala and the Arnold Arboretum believe it is worth the trouble if it is done immediately after blooming. This will save energy that will result in better blooming and health. This can be a big job, but I have found removing even half the spent flowers is helpful.
Lilacs are generally healthy if they get decent drainage, some pruning and some organic matter. But they can have a few problems. In Colorado, a warm February and March followed by a frigid April or May can freeze the buds or flowers and ruin the floral show for a whole year. Another problem can be powdery mildew, turning the leaves almost white. If the plant is strong, this will cause no real harm; just rake up the diseased leaves. Some varieties like Syringa meyeri, S. microphylla, S. reticulata, ‘Mme. Lemoine’ and ‘Pocahontas’ are resistant to mildew. You can control the mildew with a non-toxic spray of horticultural oil and baking soda, one tablespoon each in a gallon of water, or there is a new product related to baking soda called Green Cure. One other possible problem is lilac borer which can tunnel into the wood to weaken or kill stems. This should not be a problem if the plant has good vitality. I have heard “painting” the lower trunks with wood ash and water repels them.
Like every plant, lilac has its strengths and weaknesses, but far more strengths. It is truly a sustainable shrub for Colorado, being both tough and drought tolerant. Enjoy the great variety of forms, flower colors and fragrances. And by planting the early, middle and late bloomers, you can enjoy a long season of flowers. I recommend that you go to the nurseries in the spring when they are in bloom so you can smell and see, and cultivate those that really speak to you. No nursery can carry more than a fraction of even the best varieties. Two mail order lilac nurseries are Heard Gardens in Iowa and Wedge Nursery in Minnesota.
Here are a few Father Fiala identifies as some of the top varieties that are not available locally, as far as I know: ‘Flower City’, ‘Dwight D. Eisenhower’, ‘Avalanche’, ‘Violetta’, ‘Blue Danube’, ‘Mechta’, ‘Larksong’, ‘Marechal Foch’, ‘Paul Thirion’, ‘Edith Braun’, ‘Sarah Sands’, ‘Etna’.
As gardeners mature, we begin to loosen our fixation on flowers and learn to see and appreciate other aspects of plants that can be equally beautiful and enjoyable. Besides foliage color and sculptural form, texture is one of the important aesthetic elements in a garden.
Fine-textured plants can move with the breezes, glow when backlit and express gentleness and a delicate grace which is appreciated here in the rugged west. At the same time, fine leaves can be an aid to drought and heat tolerance.
We gardeners are always looking for tough plants. And those of us who are pursuing the elusive “sustainable garden” are searching for Colorado-adapted plants that do well with little or no care. But that is not enough. A sustainable garden is one where there is a balanced ecosystem of plants that can change as conditions change, to favor first one species and then another, but no plant should take over the entire space. Those dominating plants are the ones I call real weeds: the garden bullies.
Nearly everybody has met the memorable fragrance of mockorange, said to imitate the smell of orange blossoms. There are over a hundred species of Philadelphus, and of these, about 40 are native to North America. Many of the yards of Boulder County and Denver have at least one specimen. What is so good about this shrub? Dirr says, “In flower they are attractive to some, but the rest of the year are real eyesores.” Wyman said their fall color is not vivid, their fruits are not ornamental, no winter interest, but they are “cultivated 50 weeks of the year in order that their flowers may be appreciated for two weeks.” However I happen to love mockorange, and one of the 2001 Plant Select shrubs is ‘Cheyene’ Mockorange. So let’s look into the good qualities.
Hardy Geraniums are in general very serviceable and these four have been very useful and successful for me. They are tolerant of diverse and adverse conditions and are especially useful in dreaded dry shade.
In 1993 I sent a survey to 29 local horticulturists to get their suggestions on the best groundcovers for a demonstration project we were planning at Harlequin’s Gardens. I asked them to list 5-10 groundcovers that could be used to replace bluegrass in low traffic areas, that would need a quarter to a half the water of bluegrass, have few pests and diseases, would grow densely to limit weeds, would look good in most seasons and would not be invasive in gardens. The survey was typed on a typewriter and most of the replies were hand-written. People did drive cars back then. But that was a long time ago and I had a lot to learn.
Saskatoon Serviceberry (Amelanchier alnifolia)
A winter-hardy (zone 4) native shrub of the Great Plains and Rocky Mountains. It has beautiful coarsely toothed leaves that are attractive even in the dry summer. The flowers are white and apple-like, fragrant and appear very early in the spring. Delicious blueberry-like fruit follow in midsummer. Birds are very fond of them and the American Indians used to mix these serviceberries with fat and buffalo meat to make their winter staple, pemmican. The Canadians have been working to develop this plant for fruit production.
Hardy Geraniums are one of most versatile an adaptable perennials for our area. Available in many colors and habits, they can be useful in sun and shade, moist and dry, as a single specimen, as companion plants and as ground covers. These are not to be confused with the Pelargoniums which are the house plant, container and bedding plant “geraniums” which are not hardy outdoor plants in Colorado. The name “geranium” is derived from a Greek word meaning little crane, hens the common name “cranesbill” which refers to the appearance of the seed heads. The majority of the species of geraniums are native to the northern and mountain regions of Eurasia and North and South America although some are found in South Africa, India, Indonesia etc. Most grow in grasslands, meadows, roadsides and open woodlands. Therefore the natural habitat for most hardy geraniums seems to be sunny and moist or part-shade and moist or dry.
Most of our native plains plants and shrubs including:
Desert Four O’Clock
Sulfur Flower (Eriogonums)
Cotinus, known as Smoketree, is a genus of woody plants appreciated for their “smoky” flower plumes and for their leaf color, especially in autumn. Michael Dirr in his famous Manual of Woody Landscape Plants says “…it may be the best of all American shrub/trees for intensity of color.” Two species and many selections and hybrids offer leaf colors ranging from rich blue-green, maroon red, purple-red and yellow-gold; and the fall colors are even more vibrant. With the current passion for new plants, it is curious that Smoketree is not seen more often in our western landscapes.
Lavenders are great xeriscape perennials for Colorado, which bloom in the heat and dry of July and August. They are native to the rocky hillsides of the Mediterranean region. Here as well, they like good drainage, full sun, our alkaline soil and dry, loamy humus. Lavenders are aromatic herbs with gray foliage, the leaves as well as the flowers being strongly fragrant.
In our American communities, one of the responsibilities of home-ownership is to keep the ground covered. Bare earth, like weeds, indicates lack of care. So then, how do we cover the ground? The cheapest, fastest, and easiest way is to roll out bluegrass sod. “Instant” landscapes can be accomplished with a supervised construction crew that knows little about plants. And as long as water was plentiful, bluegrass was the unquestioned solution.
The 2017 Plant Select shrub introduction is a woody plant with a tongue-twister of a name, a long history of survival at the old Cheyenne Horticultural Station, and has a heart-warming story of two great local plantsmen who brought it out of obscurity into Colorado gardens.
Cotoneaster racemiflora soongorica or Sungari Redbead Cotoneaster is a very tough and beautiful shrub, having survived over 40 years of neglect at the closed and unwatered Cheyenne High Plains Horticultural Research Station. It grows 6′-8′ high and wide with arching branches. The dark green leaves that are gray-white underneath, are attractive in themselves, and the flattened clusters of white, Hawthorn-like flowers are some of the showiest of all cotoneasters. They attract bees and other pollinators. Following the flowers are showy red fruits, a quarter of an inch or more in diameter. These berries are not messy and are popular with garden birds. They cluster along the thin branches, appearing as ropes of beads — hence the common name.
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.
Many fruits can be grown successfully here on the Front Range of Colorado. At one time, there were commercial apple orchards in Boulder and Fort Collins, commercial sour cherry orchards and canneries between Loveland and Fort Collins and commercial raspberry production in various places. Cheap shipping, more reliable weather and harvests in other regions, and a raspberry disease chased these operations to other states. However there is great potential here for the home gardener to grow tree- and bush-ripened fruit that is delicious, organic, fresh and economical.
Even if the economy doesn’t drive us to foraging in the wild, there are some native fruits that are good to know, to eat and to grow at home.
Wild Plum, Prunus americana, is blooming all over Boulder and much of the Front Range as I write. It is easy to identify with its early spring clouds of white blossoms and waves of sweet perfume that carry across the yard or the ditch. It is quite happy in a ditch where it gets a little extra water, and is not at its best in very dry conditions where it will grow more as a shrub than a tree.
Plants are one of the most successful life forms. In fact, we could say that they are the most successful life form, because plants are self-sufficient. They can live without eating other beings because they can make their own food. Only plants, phytoplankton, algae and cyanobacteria can synthesize food from sunlight, carbon dioxide, minerals and water.
At the same time, plants have a serious limitation: they are rooted to the earth, so they can’t run away from pests and they can’t pursue another plant in order to have sex. But are plants helpless. Oh, no. They have developed chemical warfare and chemical magnetism to protect themselves from predators and attract allies.
“You can join the fight to save the honeybees by planting a pollinator-supporting garden.” This is a recommendation made by a Penn. State Master Gardener program. Is this weird? Not at all. The European Parliament has approved creating bee “recovery zones” across the Continent. These recovery zones will provide bees with nectar and pollen in areas that are free from pesticides. Why is it a big deal that honeybee populations around the world are declining? One reason is that one third of the human diet comes from plants that are pollinated by honeybees. Another reason is that honeybees may be the “canary in the coal mine”; just the first to show that there is a problem that hasn’t yet surfaced in other pollinators and other beings.