When cold weather returns, bulb growth naturally slows. Flower buds are at the greatest risk, and may be damaged if temperatures drop below 26°F. Foliage can also be damaged. Bulbs planted near a foundation, especially on south or west sides, or on a south-facing slope, are most susceptible to early emergence and freeze injury.

To prevent early emergence, avoid planting bulbs against foundations or south-facing exposures. Existing plantings on susceptible sites should be mulched in the fall after the ground has frozen. Use a six-inch layer of organic material, such as straw or shredded leaves.

When cold weather threatens, consider cutting flower stems if buds are showing color for enjoyment in the home. Leave the majority of the foliage on the plant for photosynthesis, food production and storage for next year's blooms.

Mite-damaged turf becomes straw-colored in irregularly shaped patches while the rest of the lawn turns green. Damage most often occurs on south- or west-facing exposures, especially if sloped, where turf is more likely to be drought-stressed.

Clover mite damage almost always occurs within 5-10 feet of a south- or west-facing building, fence, tree or other vertical structure. These mites are extremely small and hide in the turf when disturbed, making them very difficult to see. The injured or dead turf often becomes apparent long after they have ceased feeding in the lawn and it is too late to control them.

Some insecticides labeled for lawns with active ingredients bifenthrin or lambda-cyhalothrin (pyrethroid insecticides) may or may not provide control of these cool-season mites. Winter and early spring watering of suspected mite “hotspots” provide the most effective preventive and curative control. Insecticide applications are much less effective if not accompanied by irrigation.

If infested turf areas don’t recover in late spring or if turf recovery is patchy and thin, the damaged areas are candidates for lawn renovation. Refer to Fact Sheets 5.505 (Clover and other Mites of Turfgrass) and 7.241 (Renovating the Home Lawn) for additional information.

To discourage voles, rake these areas lightly and then continue with a normal fertilization, mowing and watering schedule. The tunnels should disappear as the grass begins to grow in the spring.

Populations of voles are cyclical, so they may come again for a couple of years and then disappear for a number of years. If they are causing extensive damage to trees, shrubs and lawns, use baited mousetraps to reduce their population.

Care should be taken when using traps where young children and pets have access to them.

Evergreen needles transpire or lose moisture during the winter months. To keep functioning well, the plant must replace lost moisture through its roots. But sometimes roots are unable to keep up with the moisture loss, especially in windy conditions when water rapidly evaporates from the needles. In some cases, there's plenty of soil moisture, but plants are unable to absorb it, because the ground is frozen. In other cases, there isn't enough soil moisture available to evergreens. As a result, the needle tissue dries out, turning brown or red.

To reduce or prevent winter injury, water the root area of evergreens during dry fall and winter months. When snowmelt and rainfall are inadequate, apply water monthly during warm periods when the soil can absorb it. Apply mulch over the root zone to help conserve soil moisture and reduce loss from desiccation.

Although it's unattractive, winter injury symptoms are eventually masked in the spring when new growth develops and old needles drop. Affected plant parts don't usually need to be removed.

For "Fall & winter watering" refer to message number 1706.

For more information, see the following Colorado State Extension fact sheet(s).

• Fall and Winter Watering
• Mulches for Home Grounds
• Evergreen Trees

Because rigid water scheduling may result in overwatering some plants, while allowing other plants to become excessively dry, you must be prepared to water plants on an individual basis depending on need.

There are several ways to determine when a plant needs water. Although some plants prefer their root systems to become slightly dry before their next watering, it's best to feel the soil on a regular basis and water before any wilting is visible. Other plants require even moisture and do not tolerate dry roots. These plants should be watered when the top layer of soil begins to feel dry.

The most convenient and efficient way to water plants is to pour water on the soil surface. Be sure to completely cover the surface of the soil with water so it does not simply drain down between the potting soil and the side of the pot. Plants don't tolerate waterlogged soil conditions, so don't allow them to stand in water. Plants kept indoors should be placed in saucers or trays to prevent water damage to floors and furniture. Apply just enough water to fill the tray, and discard any water that collects in the tray.

Generally speaking, it's better to water plants from the top than it is to subirrigate. Subirrigation is the process of watering plants by placing pots in a shallow amount of water in a tray or saucer, and allowing the soil to draw water up from the bottom via wicking action. It's acceptable to periodically water subirrigated plants to leach soluble salts from the potting soil.

Colorado is a large state with diverse climates and soil conditions. Often, plants from mountain soils that drain well may not grow well in compacted clay soils found in urban areas. A native plant doesn't mean the plant is drought-tolerant. Many native plants of higher elevations require plenty of moisture.

Some trees native to Colorado that are frequently used in the landscape include the limber pine, southwestern white pine, pinyon, bigtooth maple, bristlecone pine, ponderosa pine, Rocky Mountain juniper, hoptree, Douglas fir and white fir.

Shrubs suitable for landscape use such as the lead plant, mountain mahogany, Apache plume, New Mexico privet, rabbitbrush, chokecherry, three-leaf sumac, potentilla, fernbush, Gambel oak, sagebrush, western water birch and western sandcherry are native to Colorado.

For "Xeriscape plant choices" refer to message number 1907.

For more information, see the following Colorado State Extension fact sheet(s).

• Xeriscaping: Trees and Shrubs
• Trees and Shrubs for Mountain Areas
• Evergreen Trees

Water plants when the leaves start to fall in the autumn to send them into winter with adequate soil moisture. For recent transplants, a soil needle can be used on low water pressure for one minute at each site to water the root ball and surrounding soil. Make injections in a grid pattern one foot apart and nine to 18 inches deep.

Frog-eye type lawn sprinklers can be used to water established trees and shrubs. The most important area to water is from the edge of the branches halfway to the trunk, and the area two to three times that distance out from the edge of the branches. Allow sprinklers to run 30 minutes at each setting.

Monitor weather and soil conditions from November through March. Generally, if four weeks elapse without snow cover, water plants and trees again during these months when temperatures are above freezing and the soil is not frozen. Water early in the day so the water can soak into the ground before freezing nighttime temperatures.

Remember to disconnect and drain hoses after use. Don't activate sprinkler systems during the winter.

For more information, see the following Colorado State Extension fact sheet(s).

• Fall and Winter Watering
• The Science of Planting Trees

For more information, see the following Planttalk Colorado™ script(s).

• Fall and Winter Watering: during drought

Needled and broadleaved evergreens, especially last year's transplants, are very prone to winter desiccation ("winterburn") under these conditions. Transpiration from needles or leaves occurs during warm, dry winter periods. Small "hair roots" may die in dry soils leaving roots unable to replace lost leaf moisture.

The resulting water deficit causes leaf scorch of broadleaf evergreens like Manhattan euonymus, pyracantha, Oregon grapeholly and English ivy. Needled evergreens, especially Dwarf Alberta spruce, certain junipers and arborvitae, may develop extensive needle browning. Pines show needles with a "half green, half brown" look. Desiccation symptoms may be worse on evergreens in difficult sites such as windswept areas, roadsides or medians, southwest sides of buildings, and in limited rooting areas. Symptoms often appear on the most recent growth that is more succulent and prone to drying.

Homeowners should water in fall to send evergreens into winter with good soil moisture. As dry periods in winter become extended, water again. For more detail see CSU Extension fact sheet 7.211 Fall and Winter Watering. Applied in Oct/Nov, anti-transpirant sprays may help to reduce winter desiccation of evergreens.

Note that similar desiccation symptoms can result from root damage caused by certain deicing salts used on nearby sidewalks and roadways.

You can also recycle the boughs and use them as mulch in your own yard. Just cut the boughs off the trunk or larger branches and place them on your perennial beds. The boughs will protect dormant plants from drying out as fast as if they were fully exposed. They'll also keep the plants dormant longer because the soil temperature won't rise as quickly on sunny winter days. Be sure to remove the boughs as the plants start to emerge from dormancy. Then chop boughs into small pieces and add them to your compost pile to provide some acidity.

Boughs are fine for plants that should remain dormant all winter like peonies, hostas and delphiniums, but you don't need boughs for our climate-adapted plants like penstemons, buckwheats or iris. They continue to grow in our sunny winter weather, and are adapted to the vagaries of precipitation our rapidly changing climate offers.

Christmas trees are a wonderful way to start the new recycling year.

For more information, see the following Colorado State Extension fact sheet(s).

• Composting Yard Waste
• Mulches for Home Grounds

These potted trees are usually sold when they are two to six feet tall. Before purchasing one, decide where the tree will be planted after Christmas. Consider the mature size of the tree, and the weight of the potted tree. Most nurseries will hold the tree until you want to take it home.

The two most important factors for successfully growing a live potted tree are to not allow the rootball to dry out and avoid keeping the tree indoors too long. Seven days indoors is a maximum time recommended, but five days is better. Many families have developed a tradition of bringing the tree indoors for decoration on Christmas Eve and planting it outdoors on New Year's Day. It can be helpful to pre-dig the planting hole, as the ground can be frozen in late December and early January. Store the soil backfill in the garage or outdoors in a black plastic bag so it is less likely to freeze.

You can keep the potted tree in the garage for a few days before bringing it indoors, but frequently check the rootball to ensure that it stays moist but not soggy. After Christmas, the tree can again be placed in the garage for a few days before planting outdoors. While indoors, decorate the tree with small lights, which generate less heat, and place it away from sources of heat like fireplaces, heat vents and television sets.

For "Planting trees & shrubs" refer to message number 1711.
For "Fall & winter watering" refer to message number 1706.

For more information, see the following Colorado State Extension fact sheet(s).

• Evergreen Trees

Desirable tree characteristics include a full, symmetrical shape with limbs strong enough to support lights and ornaments. Non-prickly needles with a healthy green color and pleasant fragrance are important, too.

There are several steps you can follow to keep your Christmas tree fresh for the longest possible time after purchase. First, make a new cut at the end of the trunk about an inch above the old one. Keep the cut end standing in water, whether you decorate the tree immediately or store it to decorate later. If you store the tree, keep it in a cool, shaded place.

Check the tree's water level frequently, and refill as necessary. Fresh evergreen trees can take up an amazing amount of water -- up to a gallon during their first 24 hours off the tree lot. Because many tree stands have small reservoirs, you'll need to fill the reservoir twice daily.

Your tree will last longer indoors if it's located away from direct sun, radiators or heat vents, fireplaces, television sets and other sources of heat. Take care to place your tree in a location that won't block any room exits. Check electric lights to make sure cords aren't frayed or worn, and keep metallic ornaments and tinsel away from bulb sockets. Avoid combustible decorations, and make sure electrical circuits aren't overloaded.

A fresh tree that receives good care should remain in safe condition indoors for ten days to two weeks.