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Plants

Feed the Soil, Not the Plant

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?[Read More]

Flood Recovery for the Garden

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[Read More]

Easy Broadleaf Evergreens for Colorado

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.[Read More]

Climbing Roses for Colorado

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.

[Read More]

Henry Kelsey Rose

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.[Read More]

Five Little-Used Xeriscape Shrubs

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.[Read More]

What the GMO?

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.[Read More]

Goldflame Spirea (Spiraea bumalda ‘Goldflame’)

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.[Read More]

Cold-Hardy Climbers

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.  [Read More]

Philadelphus – Mockorange

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.[Read More]

Geraniums for Sun or Dry Shade

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.[Read More]

Groundcovers Project in its 18th Year

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.[Read More]

Serviceberry

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.[Read More]

Hardy Geraniums

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.[Read More]

Heat-Tolerant Plants

Most of our native plains plants and shrubs including:

Sumacs
Penstemons
Rabbitbrushes
Desert Four O’Clock
Saltbrush
Heterotheca
Artemisias (Sages)
Thelesperma
Gambel Oak
Sulfur Flower (Eriogonums)[Read More]

Smoketree

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.[Read More]

Lavandula – The Lavenders

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.[Read More]

Lawn Alternatives and Groundcovers

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.[Read More]

Sungari Redbead Cotoneaster

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.[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]