Because mowing time has been reduced in the winter months, it is a great time to do structure pruning on trees, addressing things like thinning, hard cutbacks, and general shaping. Avoid heavy pruning that stimulates new, less hardy growth. Also, wait for spring growth or the end of frost season before pruning dead branches. The damaged material, while unsightly, helps protect the remaining live tissue.

Although the outward color and appearance of a lawn during the winter can take precedence with a client, Bob Andrews, past-president of the PLCAA, stressed that turf fertilization should focus primarily on root growth. Andrews suggested a well balanced fertilizer that contains pot ash and potassium. Nitrogen fertilizers help grass to grow, but don't necessarily increase the root depth of the turf. To avoid continuous mowing, Andrews suggested that Contractors introduce iron into the turf fertilization. Iron will make the grass green, but it won't force growth.

Complete all pre-emergent applications prior to fall weed seed germination. Planned growth regulator applications are applied in mid fall. Turf fertilization and the timing of the application in the Las Vegas area are very critical because, once the turf color is lost, it cannot be regained until spring. Overall the soil in Las Vegas is alkaline. The alkaline materials in the water do not evaporate with the water. As a result, a white residue, which looks like snow, appears on the surface of the soil . Landscape companies can do a better job managing soil moisture to minimize this effect, especially during the winter months.

Sue Allen, Horticultural Specialist for Environmental Care, Inc., Dallas, Texas says Northern Texas winters are challenging because the weather extremes vary from mild winters, like 1998 where we had only 2 or 3 nights of hard freeze, to winters like 1989 where we had thirty-some days of temperatures below freezing and at least one night below 0. Such extremes are unpredictable and your best bet is to prepare the turf to go dormant above the soil level and build healthy roots below the soil level. The best regimen consists of the following:

Turf & Lawn Care

• Aerate the turf thoroughly with an aerator that will punch a hole to a depth of 1 1/2 to 2 inches. Remember to pass over the area at least twice.

• Fertilize with a blend that provides a moderate amount of nitrogen, but a well rounded micro-nutrient package. The idea is to push root development, not top growth. Texas summers are generally pretty dry and the aeration will open up the surface to allow deep penetration of water and fertilizer.

• Overseeding is a standard practice here, but there are some areas that should not be overseeded. New turf, less than a year old, is still developing its root structure. Winter grasses will compete with the new turf for nutrients and you may find that your new turf is sparse when it comes out of dormancy in the Spring. This applies to both seeded and sodded areas. St. Augustine may be overseeded, but may develop stressed areas if it is winter seeded several years in a row. Because St. Augustine is also less freeze hardy than some other types of turf and the stress of competing with winter grasses may make it more susceptible to damage.

• Don't forget to watch moisture levels during cold weather. Turf that is dry and weak is more susceptible to freeze damage and roots must have good moisture to continue to develop during the winter months.

Tips on Plant Material

The best way to protect plants from extreme temperature variance is a Fall fertilization with a balance Nitrogen/micro-nutrient fertilizer, a 3" layer of mulch and regular water.

• Mulch helps protect root systems from freezing temperatures, but it also maintains consistent ground temperatures. Northern Texas often experiences warming trends in late winter that can bring unprotected plants out dormancy and cause new growth. It is not uncommon for temperatures to drop very low after one of these warm-up's and plants can suffer serious damage. A good layer of mulch can help keep the roots cold and maintain dormancy of the plant.

• Be careful to avoid running irrigation systems during freezing temperatures. Plants can tolerate air much better than ice and the weight of ice will often break limbs. However, it is just as important to keep moisture levels even in winter as it is in summer. You may not need to run the irrigation often to achieve this, but freezing temperatures are more damaging if a plant is already in stress from being to dry.

Tips on Pruning Trees & Shrubs

Winter is a great time to do structure pruning on trees and shrubs. Your mowing time has usually been reduced and you have time to address things such as thinning, hard cutbacks, and general shaping.

• Wait until the landscape is in full dormancy. Starting too soon will result in pushing the plant into its tender growth that is more easily damaged by freezing temperatures.

• If pruning in Northern Texas (or a similar region) and you wait until late winter, be careful not to prune during one of those extra warm periods. That may result in stimulating the plant into growth. If the temperature drops very low again, the plant can suffer serious damage.

• Cutting back shrubs like hollies, eleagnus, photinias and other fast-growing landscape shrubs can reduce pruning time in the Spring and make it easier to maintain the desired height during the growing season with fewer hard prunings.

• As a general rule, you should never cut back more than 1/3 of the total height. While some shrubs will recover from a more extreme cut-back, the more you cut, the more risk you run of causing damage.

Selecting Plants

When choosing plants for the landscape, always consider the exposure. Most people will consider whether a planting area has sun or shade, but often forget to consider winter.

• A plant that would surely freeze in a northern, windy exposure may do quite well if planted in a protected, sunny courtyard.

• Trees that have an evergreen, thick canopy can provide protection for more freeze sensitive plants, although some Texas winters are too severe for that to help.

• Potted plants will be more susceptible to freeze damage than plants in the soil, because the freeze line seldom goes any deeper than 5-6 inches in Northern Texas (or similar regions). A pot allows the cold to surround the roots, so you may want to move potted plants indoors during the worst freezes.

Arizona

Richard Adkins, Account Manager for Environmental Care, Inc. Phoenix, Arizona says the desirability of living in the desert southwest during the winter months is well known, and the landscape plays an integral role. Here are a few basic tips on winterizing the landscape so you and your clients can enjoy the outdoors during its most usable season.

Turf

Lower temperatures trigger Bermuda grass dormancy beginning mid-October. Bermuda grass will often maintain color into December and January (dependent upon variety), but will eventually brown until the spring warm-up. Weed control is important during the these months to prevent weed seed build-up and keep a maintained appearance. An alternative is to overseed the Bermuda turf with Perennial Ryegrass. Perennial is preferred to an annual ryegrass due to its finer texture, dryness, and maintainability.

The overseeding process consists of decreasing irrigation prior to scalping the Bermuda to expose the soil. Certain varieties of Bermuda may require dethatching so the ryegrass seed can make soil contact. Seed is sown at rates of 12 to 15 pounds per 1000 square foot area. High traffic areas benefit from a heavier rate, while very large areas of turf retentions can be seeded lighter. Irrigate four or five times per day to keep the seed moist and hasten germination. Smaller machinery is best for the first mowing to prevent tire damage to the young stand. Application of a smarter fertilizer, i.e. 18-24-12, after the first mow is suggested, followed by routine fertilization and maintainance.

Avoid walking or mowing on wet/ frozen lawns to prevent turf damage. Be aware of low lying drainage areas where runoff ponding can freeze. Also, watch for overspray where icy sidewalks or parking areas are potential hazards.

Groundcovers, shrubs, and trees

Precondition shrubs by slowing down growth. Actively growing plants are more susceptible to damage. Limit nitrogen fertilization and avoid heavy pruning that stimulates new, less hardy growth. Irrigation rates can be decreased during the winter months, but maintaining moist soil can help prevent frost damage. At night, cooling soil water releases heat that warms the air surrounding the plant. Also, wilted plant material is more susceptible to cold damage.

Watch local weather forecasts to prepare for nights of frost. Insulate susceptible plants by covering with burlap or cloth sheets. It is best to not let the covering material touch the plant, as frost burn could still occur. These covers should be removed during the day. While mulching helps to reduce soil temperature fluctuations, protecting the roots, it can also reduce stored heat. Loose mulch and/ or removal underneath the plant is recommended.

If plants are frost damaged, consider protection with burlap or shade cloth to prevent damage by quick thawing morning sun. Wait for spring growth or end of frost season before pruning dead branches. The damaged material, while unsightly, helps protect the remaining live tissue.

General Tips

Although winter rains are characterized as light and steady, they can produce large amounts of runoff. Falling leaves and debris can clog street drains and weep holes in retaining walls. Consider ground cover, annual color, and wildflowers for areas prone to erosion. October is a good time to plant hardy annuals and sow wildflower seeds. River rock or riprap basins and swales will slow water flow and help channel drainage. Insulting smaller backflow assembles can protect the non-metallic components in hard freeze locations.

Green turf, protected shrubs and trees, color beds, and intelligent irrigation work together providing a safe and enjoyable winter landscape.

Nevada

Fehmi Midani, Service Center Manager for Environmental Care, Inc., Las Vegas, Nevada says summer to fall transition is one of the most important times of the year for a landscape company that wants to do the "right thing" for the landscape.

In Las Vegas the "right thing" comprises of knowing what to do, not only in terms of undertaking the proper cultural practices, but also knowing your pest management program and your soil makeup.

Complete all pre-emergent applications prior to fall weed seed germination. Planned growth regulators applications are applied in mid fall. Trees also receive their deep and root feeding at this time for healthy root growth. ECI advises all of their customers of the advantages and benefits of maintaining strong healthy trees year round. Turf fertilization and the timing of the application in the Las Vegas area are very critical because once the turf color is lost, it cannot be regained until spring.

Another challenge in Las Vegas is the management of soil. A certain amount of salt in our soil is not leeched out due to the limited amount of rainfall we receive annually. Overall our soil in Las Vegas is alkaline. The alkaline materials in the water do not evaporate with the water. As a result, a white residue, which looks like snow, appears on the surface of the soil. Landscape companies can do a better job managing soil moisture to minimize this effect, especially during the winter months. If they do not, they will have to continually rake the bed for an attractive soil appearance. lcm