Zoysia grass is best adapted to areas that have long, hot summers. Colorado summers are too short and the nights are too cool to allow zoysia grass to establish very effectively. It is a warm-season grass that will be green only from mid-May through early October.

Often zoysia grass is sold in small plugs that are transplanted into an existing lawn. In Colorado, the result is weedy looking because the zoysia grass does not take over the lawn. Only small patches of zoysia grass grow throughout the lawn.

Zoysia grass has definite disadvantages as a lawn grass in Colorado.

Sometimes different frost dates are quoted for each area. This risk factor presents a choice for home gardeners. How much of a chance are you willing to take in placing a tender plant outdoors?

For example, in Denver the last spring frost date at a 50 percent confidence level is May 2nd. This computes to a growing season of 157 days. If you want to be 80 percent confident frosts are past, it's May 12th. If you're not a risk taker and want to be 90 percent confident, wait until May 18th to plant. All dates are based on 47 years of data. The latest frost date in Denver was June 2nd in 1951.

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

• Vegetable Planting Guide

Basic engine maintenance is essential. Use the gasoline and oil recommended by the manufacturer. When working on the mower, be sure the blade and all moving parts have stopped. When accessing the underside of the mower for inspection or cleaning, always turn it so that the air-filter side of the mower is up. Otherwise, oil will drain out into the air filter and the engine won't start. Also detach the spark-plug wire so the engine won't start accidentally. Keep spark plugs clean; and have an expert adjust the carburetor. Check air filters regularly, and clean or replace them when dirty.

Be sure to regularly sharpen rotary mower blades, which operate on the principle of a sickle. It's advisable to have an extra blade on hand so a replacement is available when you detect poor cutting. Shredded or brown tips of grass blades is an indication of a dull or damaged mower blade. You can sharpen rotary mower blades with a grinding wheel and file, but be careful not to destroy the balance. To determine which end of the mower blade is out of balance, put a nail in the wall and hang the blade from the hole in the center of the blade. File more off the blade on the heavy end.

Excess vibration is an indication of a damaged blade, mounting, or crankshaft. Frequently tighten the blade and engine mounting bolts, as well as any other nuts, bolts and screws. Check mower wheels, bearings and axles for wear and lubrication. If there are grease fittings, check them every couple of months. Replace loose, wobbly wheels. Be sure to keep the drive mechanism on self-propelled mowers in good working order. Check belts and gears for wear and fit.

After each use, clean the underside of the mower with a strong stream of water. The metal deck can rust out if residue builds up. To reduce fire hazard, keep the engine free of grass, leaves and excessive grease. Check the grass-catcher bag for wear or deterioration, and replace when necessary. At the end of the mowing season, be sure to drain the gas and follow the winterizing instructions in your owner's manual.

To keep your mower in tip-top running condition, have a competent service person thoroughly inspect your mower at least once a year.

Plants that begin to produce more foliage at the expense of flowers may be overgrown. To determine if plants are overgrown, count the number of stems that emerge from the base. If five or more strong stems are present, the plant may need to be divided.

When dividing plants, pick a cool spell in the spring or fall, and gently dig up a clump with as many roots as possible. Expose the central rhizome or stem by gently shaking or washing away the soil. Then, with a sharp knife, cleanly slice the plant into several new pieces. Leave a minimum of two to three growing points, or it may take many years for the plants to recover. Place plants in newly prepared soil, and keep them moist until they re-establish. Share surplus divisions with friends.

It's a good idea to start with a single clump of one kind of plant until you master division, rather than risk an entire planting. Alternatively, when dividing particularly large plants, you may be able to remove a portion of a clump and leave the rest undisturbed. Replace the piece you remove with amended soil.

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

• Perennial gardening
• Choosing A Soil Amendment
• Vegetable garden: Soil Management and Fertilization
• Herbaceous Perennials
• Spring-Planted Bulbs, Corms and Roots

Puncture vine plants can be controlled by pulling them out of moist soil, but be sure to wear gloves to protect your hands from the prickly fruits. Herbicides can also provide effective control if they're applied when the plants are young and small. Certain pre-emergent herbicides, applied about April 1, can kill puncture vine seedlings as they germinate. However, pre-emergent herbicides may have to be used each April for several years to achieve good control, because puncture vine seeds can remain viable in the soil for many years.

If you decide to use herbicides, be sure the herbicide product you chose is labeled for control of puncture vine, and, as with any pesticide, read and follow label directions explicitly.

One rule of thumb is to plant trees a distance equal to at least two-thirds of their mature height from any structure.

Trees can affect the microclimate of your home in a variety of ways. Deciduous trees shade summer sun and let in winter sun, so they work best on the south side of your landscapes. Evergreen trees work well on the north side because they block severe winter winds, but they can create hazardous icy areas when planted on the south side of roads, sidewalks and driveways.

It's a good idea not to plant trees in the lawn, because trees usually need infrequent but regular watering. Lawns, on the other hand, typically need frequent waterings. Planting trees in a bed or providing a grass-free area around them protects them from lawn-mower damage.

Many fruiting trees are often used because of their beautiful, spring blossoms. But remember, fruit will replace blossoms, and may create a mess and be difficult to walk on.

Trees can be used to frame your home creating a picture in the landscape. You can maintain views under the canopy of trees and frame a view of your property.

Keep trees away from power lines and other utility easements so that after investing five or more years in tree maintenance, a utility company won't come along and disfigure or cut down a much-loved tree.

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

• Fall and Winter Watering
• Landscaping for Energy Conservation
• Xeriscaping: Trees and Shrubs
• Evergreen Trees
• Trees and Shrubs for Mountain Areas
• Small Deciduous Trees
• Large Deciduous Trees

Most Colorado lawns are comprised of cool-season grasses such as Kentucky bluegrass, perennial ryegrass or turf-type tall fescue. These cool-season grasses benefit the most from fall applications of fertilizer, usually sometime in October or November.

Applying a high-nitrogen fertilizer in April may cause grass to grow too fast, before roots can grow to support the lawn. This makes a lawn less tolerant of summer heat.

In most cases, an application of fertilizer in April is not needed when lawns were fertilized the previous fall or clippings are returned to the lawn. If an April application appears to be necessary, apply the fertilizer at a reduced rate. This may be followed by an early June application, a late August application, and the most important application in October or November.

Cool-season grasses should not be given high-nitrogen fertilizers during the heat of summer. It causes excessive, lush growth that requires more frequent mowing and watering, and the lawn becomes more susceptible to insects and diseases.

Conversely, warm-season grasses, such as buffalo grass and blue grama, should be fertilized in late June or July, when most growth occurs.

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

• Lawn Care

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

• Fall lawn fertilization: during drought

Preemergent herbicides kill very young weed seedlings but not seeds, so they must be "in place" prior to weed seed germination to be effective. One half to one inch of water from precipitation or irrigation is needed following application to move the herbicide off foliage and onto the soil surface, where weed seeds are germinating. Preemergent products should be applied during March or early April. Sites that warm earlier in the spring like southern exposures and turf near sidewalks should be treated in early to mid-March. Acceptable weed control and prevention of turf injury require uniform application at correct rates.

Some preemergent herbicides can harm the roots of lawn grasses if excessive rates are applied. A healthy, vigorous turf will enhance the effectiveness of any preemergent herbicide application. Since all preemergent herbicides, except siduron sold as Tupersan, will also kill germinating grass seed, lawn overseeding must be delayed until late summer/early fall when a spring preemergent application is made.

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

• Grassy Weed Control in Lawns
• Lawn Care
• Renovating the Home Lawn

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

• Crabgrass
• Fall lawn weed control

A healthy young tree has a main stem, or trunk, with bark that is undamaged and has not been pruned at the top. The trunk should thicken as it tapers toward the roots.

Branches should be evenly spaced about eight inches apart around the upper one-third to one-half of the trunk. Avoid trees with branches that have been pruned at the tips.

Trees and shrubs are sold from nurseries in various ways including bare root, container-grown, and balled and burlapped. Bare root trees and shrubs do not have soil around their roots and are usually less expensive than container grown or balled and burlapped plants. Bare root plants should be purchased and planted when the buds are dormant, usually in March or April.

Container-grown plants are ready to plant when their root systems are developed, and they are not placed on the market until then. Roots should be numerous and preferably not circling inside the container. These plants experience the least shock from transplanting.

Balled and burlapped trees and shrubs are dug either from a nursery field or from the wild. Those dug from the wild are called collected stock. Collected stock generally is less successful than nursery-grown stock because many roots are lost when trees are dug up from the wild. Balled and burlapped plants are only available for sale when they are ready to plant.

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

• The Science of Planting Trees

First, wound closure is most rapid if it's done just prior to when new shoots emerge.

Second, there are few insects and disease spores to infest pruning cuts.

Third, deciduous trees have dropped their leaves, so it's easier to see what you're pruning!

Trees such as elm, maple, walnut and birch are "bleeders" when pruned in late winter to early spring. This oozing sap is annoying when it drips on cars and sidewalks. There is disagreement as to whether the oozing is harmful to trees. It is thought that oozing might interfere with the closure of pruning cuts. Oozing is reduced if these tree species are pruned in the fall. However, fall is probably the least desirable time of year to prune most trees. Pruning cuts close more slowly in the fall than in any of the other seasons.

For "Pruning mature fruit trees" refer to message number 1210.
For "Training young fruit trees" refer to message number 1211.

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

• Training and Pruning Fruit Trees
• Pruning Mature Shade Trees

Removing spent flowers and cutting back foliage is the only routine maintenance most perennials require. For example, cutting faded flowers dramatically prolongs the flowering season of daisies and salvias. Removing spent flowers is usually a matter of personal taste. Some people like their gardens to appear crisp and immaculate.

Many gardeners enjoy the beauty of seedheads and wait until plants begin to look tatty and unattractive before severely cutting them back. When cutting back plants, take care not to remove basal rosettes or growing points, because it may weaken or even kill plants.

Colorado winters can enhance the subtle beauty of a border if you leave stems and stalks in place until early spring before cutting them to the ground. A thorough cutback in February or March, with a good top dressing of compost or mellowed manure, is all most standard perennials need to add years of beauty to your garden.

Don't hesitate to move plants that aren't performing well where you originally planted them. A more appropriate site can do wonders for plants that aren't performing up to your expectations.

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

• Perennial gardening
• Flowers for Mountain Communities

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

• Perennials: winterizing during drought

Snowdrops (Galanthus nivalis): Tiny, perfect-white flowers are bell-shaped and just peak above the ground at three inches tall. These bulbs look wonderful planted en masse and may bloom as early as February.

Snowflakes (Leucojum aestivum): Similar in look to snowdrops, but with each white petal having a small dot of green, they are taller—up to 20”. These alkaline-tolerant bulbs can bloom into March.

Glory-of-the-snow (Chinodoxa forbesii): This squill-cousin is a very early spring bloomer and may appear through snow. Hardy with small, star-shaped flowers with white centers, this bulb reaches about six inches tall. Though blue is the most common color, glory-of-the-snow also comes in white, lavender and pink forms. As plants grow, they will naturalize areas of the garden and can be planted in lawns—just set the mower high enough to not remove foliage early in the spring.

Fritillary: The most common fritillary is the Crown Imperial (Fritillaria imperialis), but there are many types that come in various shapes, sizes and colors. A benefit of this plant is that it’s rarely disturbed by wildlife because of its fragrance. Fritillaries come in colors of orange, red-orange, yellow, purple-and-white checked (F. meleagris), plum and white. Smaller fritillaries do best en masse, while larger varieties can become a focal point in the spring garden.

Allium: Becoming more common, alliums or ornamental onions, can create a statement in the landscape. With flowers that can reach several inches across, the bloom time for these bulbs can be anywhere from two to three weeks. Alliums bloom late in the spring into summer. Colors range from deep purple to white to burgundy. Height varies from as small as six up to 40 inches.

On February 12, 2002, EPA announced a voluntary decision by pesticide registrants to move consumer use of treated lumber products away from CCA pressure-treated wood, in favor of new alternative wood preservatives. EPA no longer allows CCA products to be used to treat wood intended for most residential settings.

According to EPA's guidelines, CCA treated wood should not be used where routine contact with food or animal feed can occur. EPA does not believe there is any reason to remove or replace CCA-treated structures, including decks or playground equipment. EPA is not recommending that existing structures or surrounding soils be removed or replaced.

There is nothing that can be added to the soil to neutralize arsenic or convert it to something that is less toxic. Arsenic may be taken up by plants if the arsenic concentration in the soil is very high - greater than 100 ppm. Arsenic levels in soil that are affected by treated timbers usually range from 10 to 20 ppm arsenic.

It is rare to find vegetables contaminated with arsenic in beds surrounded by treated wood, since the arsenic is confined to the area occupied by the wood itself. If the wood is removed, then the soil where it came into contact should be covered with topsoil or removed.

Copper treated wood is a better alternative to CCA treated wood since copper is not nearly as toxic as arsenic. However it should be handled with gloves and a dust mask should be used when cutting it. This treatment can be a concern if this lumber is sawed or sanded and dust is inhaled.

Another lumber choice for gardening applications today is naturally rot-resistant wood such as redwood or cedar. These are a good choice for gardens where food plants (vegetable, fruits) are grown.

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

• Sustainable Landscaping