by Mary Aukema
Colorado State University Cooperative
Extension Master Gardener
Larimer County
Selecting the right tree for the right location can be a bit of a challenge during an ordinary Colorado spring and 2004 is shaping up to be yet another dry year. This along with our unpredictable spring weather can make selecting and planting a tree a bit dicey. We can't control the weather, but we can take some precautions to avoid loss of trees due to environmental factors, disease or insect damage. Should you plant a tree during a drought? There are valid arguments on both sides. A few reasons to go ahead and plant: the new tree can replace old and dying trees, it can provide shade and therefore reduce some energy use now, and much more in the future. New trees stop soil erosion, and reduce storm water runoff. Planting more than one kind of tree gives us some protection from diseases like Dutch elm disease. This one disease caused the loss of many of our elm trees several years ago.
The following are some things to think about when shopping for a tree. Take a minute to picture a tree in your landscape. Will the tree have enough room when it reaches its mature height and branch spread? Is the tree in a location that is easy for you to water? Plant your tree correctly with the latest planting techniques, and water at the appropriate times. Select a tree that is smaller. Evergreen trees can be 6 feet or under, and deciduous trees are fine if they are 2 inch caliper or less. A small tree will establish in your landscape quickly. It usually takes a full calendar year per inch of trunk caliper for trees to become fully established. Be sure and water the tree in fall and winter, as well as in spring and summer. Ask if the tree was seeded or propagated in Colorado. Trees that have a local seed source are more likely to do well with our environmental conditions. Finally, shop at a reputable, local nursery.
Deciduous trees
We are fortunate that there are many trees that do well along the Front Range and in our drier conditions. The following are but a few.
* Acer grandidentatum, canyon maple or big tooth maple is a multi-stemmed small tree with beautiful fall color.
* Acer tataricum, tatarian maple can be single or multi-stemmed, and has pink to red winged seeds in the summer. It does well in our alkaline soils and has an irregular, rounded shape.
* Catalpa speciosa flowers in June and is very cold-hardy. The leaves are shaped like large hearts. It is known for its trumpet-like flowers and its large seed pods.
* Celtis occidentalis is not a fussy tree at all. This common hackberry is tolerant of drought, wind, and most soils. Hackberry trees have a delightful yellow fall color.
* Crataegus ambigua, Russian hawthorn, has a gorgeous canopy for a smaller tree. This hawthorn has smaller thorns than other hawthorns. It has beautiful spring flowers, grows in a spreading habit and has beautiful red fruit.
* Crataegus phaenopyrum, or Washington hawthorn has an upright growth habit, white flowers in the spring that turn to a dazzling orange-red fruit, and a canopy of red-orange leaves in the fall. Although the Washington hawthorn will take a bit more water, the color in the fall is spectacular.
* Pyrus ussuriensis is the hardiest of all ornamental pear trees. It has a dense, rounded habit with glossy dark green leaves and flowers that are light pink to white.
* Syringa reticulata is a lilac that is a bit unconventional. This Japanese tree lilac, with its mature height of around 20 to 25 feet, can be planted in tighter landscape areas around the house. Although the flower scent is not the same as the common lilac, the appearance of the tree in bloom in June is a welcome treat.
Evergreen Trees
When selecting an evergreen for your landscape make sure you have adequate drainage and sufficient room for the tree to grow to its mature height and width. Some conifers that do well in Colorado are:
* Juniperus scopulorum is also known as Rocky Mountain juniper. We are fortunate that this tree comes in many shapes and sizes, and the colors can go from green to bluish. All are drought tolerant.
* Juniperus monosperma is also called the one seed juniper. This multi-stemmed tree has small, scale-like leaves. It is often found growing with pinyon pines on dry, rocky slopes.
* Pinus edulis or pinyon pine is a handsome tree that does very well without supplemental irrigation. It does not do well when planted in an irrigated landscape. The bark is red-brown to gray, and has an irregular crown. The seeds are edible and do attract wildlife.
* Pinus flexilis, limber pine, has very flexible branches that have dark, bluish green needles. This picturesque tree is wind-tolerant and adapts easily to dry soils.
For more information on selecting trees that do well here, planting and watering guidelines and additional drought information, check out the following Fact Sheets #7.403 - Evergreen Trees; #7.418 - Small Deciduous Trees; #7.421 - Native Trees for Colorado Landscapes. Web sites with information are:
http://www.colostate.edu/Depts/CSFS/csfscf.html
http://www.colostate.edu/Depts/CSFS/urban.pdf
Q: I am concerned about a late freeze or snow. Will perennials survive a spring frost or even snow?
A: Snow is a great insulator and may protect hardy flowers from frost. Tolerance to the freezing temperature depends upon the plant. Spring bulbs, such as the tulips now blooming, will survive temperatures of 29 degrees Fahrenheit or above. Plants located close to the house will receive protection; south-facing slopes are more at risk because these areas warm up earlier and produce new, vulnerable growth. Perennials that emerge early are usually cold hardy. Pansies will tolerate some frost. Annuals such at impatiens, tomatoes and other late spring plants will not tolerate cold weather. Covering plants with mulch or row covers on very cold nights will protect tender perennials.
Q: I want to plant a salsa garden that will not be ready until August. When should I plant my cilantro?
A: Coriander (Coriandrum sativumis) can be used to describe the entire plant: leaves, stems, seeds, and all. The leaves of the plant are commonly called cilantro, which comes from the Spanish word for coriander. The leaves of this fast-growing member of the parsley family have a very distinctive bold flavor. Sow the seeds twice a year where you want the plants to grow—first thing in spring and again later in the summer for an August crop. Choose a sunny spot and cultivate with compost. For quick germination, soak seeds in water overnight before planting. Bury the seeds half an inch deep. If too many seedlings appear, thin the plants to about five inches apart. Coriander can be transplanted with minimal disturbance to the roots, but this plant grows so well when sown directly into the garden that starting seeds indoors is hardly worth the trouble. Begin picking the leaves when the plants are about six weeks old to use in salads, salsa or other spicy dishes. When the weather heats up, the plants grow taller and flower. Coriander is the seed of the plant and has a totally different lemony taste.
Q: Native plants are becoming very chic. They have been "in" before; usually when the West is in a drought. The current popularity seems different and more permanent. Why are native plants a good choice for Western gardens?
A: Native plants are those that were growing naturally in the area before humans introduced plants from distant places. Native species thrive under the local conditions while being less likely to invade new habitats. Native plants have been adapted to local environmental conditions for hundreds of years. When placed is a similar condition in the landscape, they can be vigorous and hardy and can survive winter cold and summer heat. Once established, they require little water and no fertilization. Native plants improve soil fertility, reduce erosion, and often require less fertilizer and pesticides than many alien plants. These characteristics save time and money for the gardener in addition to being relatively "low-maintenance." Native plants provide familiar sources of food and shelter for wildlife. As natural habitats are replaced by urban and suburban development, the use of native plants in landscaping provides essential shelter for displaced wildlife.
Bare root "whips" of fruit trees are available now from nurseries
and mail order catalogs. They have few if any branches and should still be dormant.
After planting, remove the top of the whip about 1/4" above a bud that
is 2.5 to 3 feet above the soil line. This will force branching. If the tree
already has branches, only remove the ones that are dead or broken. The tree
will need as much foliage as possible the first year for food production and
to establish a good root system.
Some blue spruce trees around town are being removed because they are infested with Ips beetles, a bark beetle that attacks pine and spruce. They usually only successfully invade dead and dying trees but can also attack trees that are stressed. Apply preventative spray to the trunk and major limbs before beetle activity in the spring and a later summer application may be necessary. Products containing carbaryl (Sevin) or permethrin are commonly used. Once Ips beetles have moved into the wood the tree cannot be saved and beetle control is limited.
"Tax Day" or Easter – which ever one is easier for you to remember – is the day to remove the tree wrap from your trees.
Labeling on fertilizer bags can be confusing. The three numbers on the bag refer to the percentage of N (Nitrogen) Phosphorus (P) and K (Potassium). They always appear in the same order. Nitrogen aids the plant in the production of green tissue. High nitrogen content makes your grass greener and promotes leafier plants. Phosphorus promotes root development and flowering. So for vegetable gardens or flowering plants and shrubs look for a fertilizer higher in P than N or at least the same. K – Potassium helps promote general plant health and vigor.
The authors have received training through Colorado State University Cooperative Extension's Master Gardener program and is a Master Gardener volunteer for Larimer County.
Gardening and Insect Fact Sheets are available on-line by clicking HERE.
Return to Master Gardener Articles