Now is the Time to Mulch Your Planting Beds

Very few materials distinguish an exemplary landscape from an average one like a layer of fresh mulch. When performed well, the visual impact of having a new layer of mulch spread over the planting beds is striking in comparison to an adjacent property which has not been mulched for several years. Attention to such details as mulching the planting bed areas is an indication of the concern the homeowner or property manager has for the landscape. Although I have spoken in earlier articles of the importance of mulch, I felt this would be a good time to remind ourselves of how the practice of mulching will benefit us and our landscapes.

There is an obvious and immediate visual benefit to your property as a fresh layer of mulch provides a distinct line of demarcation between the lawn and bed areas and improves the curb appeal of your home. There are some less obvious reasons for mulching your planting beds though. From a landscape management perspective, a layer of mulch between two and four inches thick provides a weed control measure. Most weed seeds are tiny and have a limited supply of stored food. Germinating weeds must produce their leaves quickly before this food supply is exhausted if they are to survive. When a weed seed falls on bare soil, the weed quickly establishes itself to become an eyesore as long as there is enough soil moisture and sunlight. Mulch materials do not provide a good environment for weed seedlings though. Mulches are very porous materials which dry out quickly between irrigation and/or rain cycles. Weed seeds which blow onto a layer of mulch often dry up and wither away before the weed seedling has a chance to get established in the landscape.

Mulches may be thought of as a thermal blanket to protect the root system of your landscape plants. Although the stems of trees, shrubs, and groundcovers may withstand cold temperatures common to our area, most roots will be injured when the soil temperature drops below 40 or 45 F. Also, roots can be injured or killed by excessively hot temperatures during the summer months. Any injury to the root system will be expressed in the stems, leaves, flowers and fruits of the plant. Mulch moderates temperature extremes throughout the year to help protect the plant. The highly porous nature of mulching materials forms dead air spaces within the mulch profile to insulate the soil from the high and low temperature extremes of the surrounding air, just as double- and triple-pane windows provide insulation for your home.

Timely application of mulching materials is a valid horicultural practice for conservation of resources. During hot weather, much of the soil moisture needed by plants is lost through evaporation. To compensate for this loss, the irrigation rate must be increased, but that ultimately affects personal finances. Bare soils quickly heat up during the hot summer days, increasing evaporation losses. The same temperature buffering qualities which protect plant roots from temperature extremes also reduce evaporation losses from the soil and conserve soil moisture.

We have all seen the effects of heavy rains on bare soil, especially in sloped areas. A layer of mulch over the planting bed areas is an important soil conservation practice. Without a layer of protection for the soil, the outer layers of soil are carried away by wind and water movements. The loss may be gradual or it may be sudden, but the result is loss of a valuable resource.......the soil itself. In time, erosion exposes plant roots to the air where they quickly dry out and die.

Most people do not think of mulch as a defense against plant diseases. However, many foliar diseases of plants occur when fungal spores on the surface of the soil are splashed onto plant leaves whenever it rains or the irrigation system is running. When water droplets strike the angular mulch particles, they disperse along the surface of the planting bed rather than deflect upward toward the plant. It has also been shown through horticultural research studies that certain types of hardwood bark mulches...... the most common mulching material in our area..... has a chemical composition which inhibits certain plant disease pathogens.

Since most mulching materials are organic in composition, they eventually decompose through the activity of microorganisms . This has both positive and negative aspects. The negative aspect is that the material must be periodically replaced. With the rainfall and temperatures of our area, the decomposition rate is high enough that the mulch should be replaced about once a year. The positive aspect of mulch decomposition is that the mulch breaks down to form a highly organic soil amendment. As the mulch breaks down to simpler components, these materials move downward with rainwater and irrigation to the underlying soil. As percentage of organic matter in the soil increases, so does the soil's aeration, water-holding capacity and nutrient-holding capacity. Over time, the soil develops a more organic nature which is highly favorable to plant root growth and development. In light of the many benefits, having your planting beds mulched when needed is a worthwhile investment in the health and quality of your landscape.

Proper Pruning of Crape Myrtles

There continues to be a lot of confusion about the proper way to prune and train Crape Myrtle trees. I have seen these trees pruned as early as November or as late as April. I have noticed some Crape Myrtle trees to be pruned back each year in such a severe manner that only the trunks remain after the pruning operation, but I have also found this same type of tree to receive little, if any, pruning. Does it matter how or when these trees are pruned? Should these trees be pruned? For this article, I thought it would be helpful to address some of these questions regarding the pruning of trees in general and of Crape Myrtle, in particular.

There are several valid reasons for pruning Crape Myrtle trees as well as other trees found in the landscape. As with any living thing, there is the possibility of an attack by disease microorganisms, primairily fungi and bacteria. If a limb or branch dies due to disease, this tissue can become a hazard. This is especially true if the limb is large and is extending over the car in your driveway. You just never know when the dead limb will snap off and fall on whatever or whoever happens to be beneath it. Since Crape Myrtles are small trees, any fallen limb is not likely to do major damage, but it could still scratch a car parked beneath the tree. Strong winds and excessive weight from ice or snow can cause limbs to break and eventually fall to the ground. Even before the dead limb falls to the ground, it is an unsightly blotch in an otherwise well-manicured landscape. For these reasons, any dead limbs should be removed whenever they are detected.

In the landscape, it is a common sight to find limbs which cross-over and rub against each other. In time, rubbing branches create wounds in the stem tissue which provide entry points for disease organisms. One of the purposes of the bark is to provide a protective layer of tissue to protect the inner vascular system of the tree. The vascular tissue, xylem, is responsible for carrying water and nutrients from the roots to the rest of the plant. The other vascular tissue, phloem, is responsible for carrying food, which is manufactured in the leaves, to other parts of the plant. Damage to bark allows disease organisms to attack these essential vascular tissues which can, in turn cause death of limbs and affect the health of the entire tree. Whenever possible, it is important to eliminate rubbing limbs and branches in trees to maintain good health of the plant.

One of the reasons that Crape Myrtles are such popular trees in our area is that they produce an abundance of flowers throughout the growing season. The flowers form on the tips of the limbs in a clustered arrangement referred to as a panicle. However, these flower clusters readily absorb water from rain. This can add enough weight on the limbs to cause them to bend to the point of breakage. Limbs broken from this excess weight should be pruned off as soon as the problem is found. This problem is most easily detected after a few hours of rain. Thinning out of limbs once a year will minimize this problem because there will be fewer flowers to absorb rainwater. When trees are thinned out properly, there will not be a noticeable reduction in flower production and the shape of the trees will have maintain a desirable shape.

At the end of the growing season, the flower petals drop off, but the flower stems remain attached to the tree. These old, unsightly flower stems die and will remain on the tree through much of the following year unless they are removed. In February, Rich-Way Landscape employees prune out these old flower stems using hand pruners. They also inspect the trees for rubbing or diseased stems to proactively eliminate possible health problems to the tree and to minimize hazardous conditions to people and property beneath the tree.

As a general rule, it is best to do the majority of tree pruning work during the dormant season. Pruning trees too early in the year, such as in October and November will expose the tree to chilling injury. Pruning wounds need to have time to heal over before being exposed to cold winter conditions. This is the reason Rich-Way employees wait until late January or February to provide most of the pruning of Crape Myrtles.

As you drive around town, you may notice many Crape Myrtles which are severely pruned back to some arbitrary height on the trunk of the tree, leaving large wounds. In the landscape trade, this practice is called "dehorning", "tree topping" and sometimes "Crape Murder". When this practice is done, the tree responds in the same way it would if it were to suffer a catastrophic loss of leaves due to storm damage, insect pest defoliation or plant disease. The tree produces many fast-growing limbs at the pruning wound site, each limb producing many large, succulent leaves. This plant response is an attempt to reestablish the balance between the plant roots and the plant tops. Without a rapid increase in leaf production, the roots would not be able to get enough food so they would die. Ultimately, this results in the tree going into a steady decline in its health and possibly death of the entire tree. The rapidly growing limbs which are produced originate from a specialized type of bud which lies dormant unless activated by a catastrophic leaf loss. These buds are formed just beneath the outer bark layer so the stem which originates from them are weakly attached to the "parent" limb. Such weakly attached stems are readily broken by winds and heavy rains so even further damage to the tree is probable. Furthermore, this practice destroys the shape and structure of the tree. It may take years of careful retraining of the tree by skilled horticultural technicians to regain the desirable shape the tree once had. Unfortunately, even this effort may be insufficient for the tree to reach the potential it once had.

We all need to work together to be educators to those less knowledgeable in proper tree care. As you see your neighbors incorrectly pruning their crape myrtles, even though their intentions are good, please share with them what you've learned about proper tree care or ask them to give us a call.

Lime-Does My Yard Need It

We would like to offer you a supplement to the current plant nutritional program for your lawn. Many of you may have heard of the process of liming you lawn, but may not be aware of how this process can benefit your lawn. Liming is a method of improving the efficiency of fertilizers applied to your lawn.

One of the indicators used to evaluate the health of your lawn is the soil pH. Soil pH is a measure of whether the soil is acidic or alkaline. The pH scale ranges from 1 to 14. Soil pH levels approaching 1 are very acidic whereas levels approaching 14 are very alkaline. A pH level of 7 indicates the soil is neither acidic nor alkaline and is often referred to as being neutral. Lawns prefer a slightly acidic soil pH in the range of 6 to 7. This is true of many shrubs, although certain acid-loving shrubs such as azaleas and camellias prefer a pH in the 5.0 to 5.5 range.

When plants are growing in ideal soil pH levels, nutrients from fertilizers are readily available for uptake by plant roots. When the soil pH is either too high or too low, certain plant nutrients tend to react chemically with other components found in soil to form insoluble compounds which cannot be absorbed by plant roots.

As a general trend, the soil pH tends to decrease over time because rainfall and irrigation tend to wash out soluble basic components in the soil. Therefore, the soil tends to become more acidic. Over time, plants may develop nutritional deficiency symptoms because the nutrients are unavailable by the plant even though they are present in the soil. The nutrients may be in the soil, because fertilizer was applied, but the nutrients may be in a form that cannot be absorbed by plant roots. To counteract this effect, horticulturists apply some form of liming material. A liming material raises the soil pH so that nutrients will become soluble and available for toot uptake. Therefore, the fertilizer efficiency is greatly improved.

If you are interested in finding out if liming would benefit your lawn, Rich-Way will provide a soil test to determine if you need this service performed. The normal fee is $25.00, but we will waive this fee for January and February.