Is Landscape Mulch A Gardener’s Best Friend?

It is simple – Mulching… Of the 100’s of innovations, labor savings introductions, tools and ideas, designed to help us in the landscape, lawn or garden get more done with less work.

However, landscaping with mulch is one old, tested and really wonderful garden operation, crammed with labor saving possibilities, which has been much heralded, but all too little accepted by gardeners as a whole.


And, as if this were not enough, many mulches, great time savers that they are, cost little or nothing. It is a mystery why more people do not take advantage of mulching with different types of mulch in more of its varied applications. Read on to learn more about the best landscape mulch.

Mulches for Winter Protection

Mulching for winter protection has, of course, long been necessary for many plants in all regions of really cold weather.

There are enormous benefits, however, which come from mulches in place during the growing season. Some kinds even remain on indefinitely, with new material added as the lower layer breaks down helping build a good soil structure and becomes incorporated with the soil, similar to a compost pile.

It is the “all season” or at least the “growing season” mulch which is here being discussed, rather than that cover which is in place only during the dormant season.

Possibly the neglect of this operation is due to the fact that all too few gardeners know most of the virtues of mulches. Many garden writers and lecturers are at fault here, in that they tend to stress only a few of the more readily apparent reasons why organic mulches should be used.

Why Mulch?

The most common reason given for using a mulch is that it will eliminate, or at least retard, weeds. This in itself should be reason enough.

Where the mulch layer is sufficiently deep, this discourages weed growth in that area. These few can be pulled readily from the loose, fluffy mulch layer.

In addition, most mulches help greatly in conserving moisture. This, too, is almost a sufficient reason why mulches should be more widely used than they are.

It is here that many writers stop, as if that were the whole story. Actually the combination of benefits listed below may well have more value than both of these virtues combined.

A Good Mulch

A good mulch tends to keep the soil cool in summer and retards freezing-thawing cycles in winter. The first is especially important with rhododendrons, azaleas and related plants. Most other plants benefit somewhat, even if to a lesser degree.

The reduction of alternate freezing and thawing is important to all perennial plants not blessed with a very deep reaching root system.

An exception to this characteristic… black plastic sheeting , which actually increase soil heat, are used to speed up the maturity of early crops. Tomatoes, strawberries and other like plants react well to such a practice.

Take your choice, you can’t lose!

Improves Soil Breakdown

Next on the list could well be the improved aggregation of the soil beneath the mulch. If your soil is less than perfect, either toward the light or heavy side, this will be a big benefit in building good soil structure. In the breakdown of organic matter, some gummy substances are produced which clump soil particles together.

This improves light soils by making them more retentive of both water and nutrients. In the case of heavy soils such aggregates open the dense structure allowing better drainage, increased root activity and a better movement of fertilizing materials through the soil.

Tied in with this question of aggregation is another plus for mulches. Where soils are “open in structure” there is better gaseous exchange between the air and the soil. Don’t forget that oxygen is necessary in the soil if roots of most plants arc to grow.

Where the soil, or mulch, surface is open and the structure is well aggregated, exchange is ample and plants grow vigorously.

Most of us garden where the topsoil is not as deep as we would wish. As mulches disintegrate over the seasons many of them add to the depth of the existing soil, helping build good soil structure. With readily decomposed materials, like crushed corn cobs, the buildup may be appreciable.

On the other hand, materials such as buckwheat hulls break down very slowly, and have little of this value.

Increase Soil Bacterial Activity

Under many mulches there is an increase in the bacterial activity of the soil. As the breakdown of humus and the full availability of some elements of fertility are dependent on the activity of beneficial bacteria, this is not an item which should be overlooked.

Insulation In Spreading Disease

Another insulating property of some mulches is their effect as a physical barrier to the spread of disease. Blackspot of roses, for example, winters to a great extent in the soil.

Learn more on Mulching Roses

When a sufficient mulch of good clean material, such as peat moss or pine needles, is put in place after the spring clean up, it becomes almost impossible for rain to splash the blackspot spores up onto the leaves where damage can be done.

Preventing Soil Erosion

Not the least of the benefits of mulching comes from the prevention of soil erosion, either by water or by wind. In the Memorial Azalea Garden at the Biltmore Estate, there are some very steeply sloped beds. At one time oak leaves were put through a hammermill to come out in pieces between one-half and one inch in size and used to mulch the flower beds.

Not only is there no soil erosion but the mulch itself does not slip down the grade. This material works well with all rhododendrons, including azaleas, kalmias and hollies.

Added Soil Fertility

Many gardeners expect a considerable dividend in added fertility when a mulch breaks down and becomes part of the top soil. This is, to a great extent, wishful thinking. It is true that there is some release of fertility elements, but for the most part, barring animal manures and leguminous hay, this is slight and can be disregarded when you estimate your fertilizer needs.

Mulches under strawberries and tomatoes keep the fruit clean. Under fruit trees and shrubs, they also prevent the bruising of dropped fruits. In the ornamental garden they prevent splashing of mud on low growing leaves and blooms. In the rock and alpine gardens this is an important consideration.

Helps Domestic Relations

While speaking of mud, we might consider how your spouse will cheer when you come from the mulched garden right after a rain. Your shoes will be clean! This is of no benefit to plants, but wonderful for domestic relations.

When the soil is wet, however, and you have to walk around a bit, the mulch will help preserve the good soil structure. That is of importance to plant growth.

And finally, cultivation damage to shallow rooting plants will be a thing of the past once your mulch is in place.

If this were an exhaustive study of the subject, other benefits might be mentioned, but these are the main factors which should be considered.

Mulching Materials

The next point to appraise is what materials make the best mulches? That isn’t an easy question to answer. Not all materials have all the beneficial effects listed below.

In deciding the best landscaping mulch, the material you will use in your garden, test each candidate against these criteria:

  • Is it available locally and cheaply? It should carry no weed seeds or disease.
  • It shouldn’t blow badly in high winds. (In questionable cases, can it be anchored readily with easily obtained materials?)
  • It should not crust or pack enough to shed water or interfere with gaseous exchange.
  • It should have an inconspicuous or pleasant color (pine needles, buckwheat hulls, shredded bark) and yet not attract attention to itself (bright new straw).
  • It should not be a fire hazard.
  • It should not have an offensive odor, at least in the long run. (Spent hops smell like a brewery for about ten days, but then are no bother.)
  • It should be easy and safe to handle – bagged mulch is easy to handle
  • The length of effectiveness has some bearing, too.
  • And finally, is the material readily available, but only in a very “fresh” state? Fresh sawdust has long been considered poor mulching material, but really only needs a minor treatment to be perfectly safe.*

*Fresh sawdust, grass clippings, pine bark, pine straw, wood chips or wood mulch and like materials start their breakdown quickly and then tend to taper off. In this breakdown bacteria are an important agent. They require appreciable amounts of nitrogen for their activity. In most soils there is not enough nitrogen for both the bacteria and the plants too. In such a situation simply add two pounds of ammonium sulfate (especially good for acid-loving plants) or its equivalent from another source, to each inch of mulch material per hundred square feet of the soil surface. This will lake care of the bacteria. On the completion of their breakdown job, they will die and release this material for plant use.

Now this all seems like quite a list of potentially restrictive criteria. The encouraging point is that several widely and cheaply available materials score reasonably high in such a screening.

One outstanding material is shredded bark – it is 100 per cent organic, and its dark brown color is handsome to the eye. Shredded bark mulch is an easy bag of mulch to handle as well.

How Much Mulch? – Some Mulching “Don’ts”

  • Don’t place wet mulches, such as manure or peat moss, right up to the stems, especially for winter mulches, or rots and cankers will be encouraged.
  • Don’t pile all of the mulch material on at one time if you are in doubt as to how much it will settle. It is better to build the mulch with a couple of applications. Some mulches settle tremendously and three or four applications may be necessary before an adequate, stable level is reached.
  • Don’t put fluffy winter mulches on too early, that is, before hard frost. Such a practice encourages mice to nest in the mulch material.

Then when the winter becomes really rough, the mice will feed on the bark under the mulch, girdling the plants. This is especially true of fruit trees.

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