Mulching Roses Save Time Money Water and Effort

Orange flower giving and enjoying life

Ask a professional landscape or any real down-to-earth enthusiast of ornamental plants what particular technique of gardening saves the most time, effort, water and money; the answer will be… mulching.

How can time, effort, water and money be saved by mulching? What is mulch?

First, it would be well to state that gardening involves not only the production of vegetables. and fruits, but the art and science of caring for ornamental plants, whether they be flowers, shrubs, trees or grasses.

The home gardener is no longer considered one who has a large vegetable patch in the backyard, they have now become a home-grounds beautifier… planting flowers, shrubs, trees and lawns around the home with the main purpose of beautification.

Second, the home landscape/gardener likes to live and play in the yard. Third, they may possibly have a small corner plot of vegetables.

Basically, the maintaining of home grounds or estates’ plantings requires common sense, keen observation and a good measure of pride.

Automatically the gardener’s seeing sense mentally records the plant’s characteristics, such as growth habit, bloom period, height, color, etc.

Common sense, combined with this seeing sense, guides the home gardener in applying the techniques of planting, pruning, fertilizing, watering – irrigation, pest control, mulching and weed control. Each technique is a topic in itself.

Mulching, however, directly affects watering, weed control and fertilizing.

What is Mulch?

A mulch is any material applied to the surface of the soil primarily to prevent loss of soil moisture by evaporation and to check weed growth. The mulch material may be organic or artificial.

Organic simply means a material of plants or plant parts. Ko-K-O,** the dry, brown outer shell of the cacao bean is an organic mulch material. These shells come off the bean immediately after the roasting process and are separated from the beans by strong air action, thus insuring a dry, weed-free product.

In 1937, when the Hershey Rose Garden was opened, a wide variety of mulch materials was employed. Cocoa shells became available in quantity and Ko-K-O was used on all areas of the Rose Garden and estates plantings. In order to save water, time, effort and money, a one to three inch layer of the shells was applied.

This layer needed to meet the primary requirement of conserving soil moisture and did so by acting as a barrier. Soil moisture is lost by evaporation into the atmosphere. Water moves up to the soil surface by capillary action, clinging to the soil particle surfaces and pore spaces.

This evaporation is prevented by the honeycomb structure; the pore spaces are too large to maintain capillary activity, yet not too small for air to reach the soil surface freely.

The Ko-K-O mulch was coarse enough to admit water readily, get wet itself, but yet not absorb excess quantities of water. These characteristics were found to be ideal since irrigation at the Rose Garden was by overhead sprinkler.

Materials which deter water entry or soak excess water mean longer periods of watering and greater volume required, resulting in higher water costs. Any material blocking the ready entry of water, either by self-absorption or fine granulation, lacks the qualities of an efficient mulch.

A mulch is not used to prevent entry of water nor to stop air movement into and out of the soil. Aeration must be maintained; otherwise, the carbon dioxide given off by the roots has no means of escape; instead, it mixes with soil water to form carbonic acid which leads to a sour soil condition.

One of the many excellent features learned of Ko-K-O was that it would not pack, even after prolonged breakdown. Some which remained in place for three years and still maintained coarseness and spongibility – that ability to remain loose and absorptive like a sponge.

With great numbers of woody ornamental plant materials, there was an important factor to consider when mulching: Will the mulch material heat upon breakdown? Excessive heating or oxidation of a mulch will burn bark off woody plant materials.

Extensive use of Ko-K—O revealed that it broke down or oxidized so slowly that no heating was evident, thereby permitting the mulch to be applied directly on woody plants such as roses.

Nitrogen Loss

Along with excessive heating goes a nitrogen shortage, as soil bacteria utilize the available soil nitrogen for energy during the breakdown process. Thus, materials such as fresh woodchips will tie up nitrogen during breakdown to such a degree so as to cause nitrogen deficiency in the plants.

rose close up

To overcome this nitrogen shortage, chemical nitrogen must be applied with mulches. It was found in the use of Ko-K-O on the entire Hershey Rose Garden area that no extra nitrogen was needed when the material was applied.

As a matter of fact, since Ko-K-O was used at the Gardens, only two, instead of three, feedings were applied yearly to the roses. Where complete fertilizers were used only the March feeding was a complete fertilizer and the second feeding in August was 0-20-0 or 0-10-10.

This saving of fertilizer and labor for application was significant in no small way.

To continue with the outstanding merits of Ko-K-O, it must be mentioned that unlike straw, hay, leaves, sawdust or wood chips, it did not harbor insects or animals, nor has any plant pathogen had been associated with the material.

Straw, hay and leaves as mulch materials afford hiding or living areas for field mice and rabbits. Corncobs usually carry the corn insects which have been found to attack roses. Sawdust, wood chips and leaves are natural habitats of termites and plant pathogens.

Mulches are used for winter protection with the hope that the material will stay in place, keep the soil warm and protect the lower portion of roses and perennials, such as peonies, phlox, chrysanthemums, etc., against winter winds and temperatures.


A mulch, if dark brown will absorb the heat of the sun and thereby tended to keep soil underneath warmer than will light-colored mulches.

Summertime effects of heat absorption by the material act favorably, too, since the trapped heat is given off during cooler portions of the day and night, thereby counteracting too rapid cooling or too great a drop in temperature in the near vicinity of the plants.

Light color mulches reflect heat and light so that the undersides of the plant leaves are warmer during the daylight hours.

Image: mrkathika

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