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Publication #FOR 68

Landscape Mulches: How Long Do They Retain Their Color?1

Mary L. Duryea2

Landscape mulches contribute to the beauty of Florida's urban gardens and landscapes. The contrasting color of the mulch compared to the plants contributes to a natural yet neat appearance. Yet, in addition to beauty, mulches provide a number of other benefits. Mulches are known to buffer soil temperature, prevent water loss from evaporation, and control weeds. These advantages along with the attractiveness of mulch have resulted in a variety of mulches available for the gardener and landscaper.

Many questions emerge about the benefits of various mulches. One common question is: How long do different mulches retain their color? As mulch ages and is exposed to the sun and rain, it loses its color and may need to be replenished. This article is one of a series of fact sheets, which compare six common Florida landscape mulches (Duryea et al. 1999; Duryea et al. 1999).

Figure 1. 
[Click thumbnail to enlarge.]

The Study

In this study six landscape mulches were compared:

  • Cypress (bark and wood from Taxodium distichum [L.] Rich. and Taxodium distichum var. nutans [Ait.] Sweet)

  • Eucalyptus (bark and wood from Eucalyptus grandis W. Hill ex Maiden)

  • Melaleuca (bark and wood from Melaleuca quinquenervia [Cav.] S.T. Blake)

  • Pine-bark (mostly bark from Pinus elliottii [Engelm.] and Pinus taeda [L.])

  • Pine-straw (needles from Pinus elliottii [Engelm.])

  • Gainesville Regional Utility (GRU) mulch containing utility-prunings (leaves, bark and wood) from oaks Quercus laurifolia Michx., Quercus rubra [L.], and Quercus virginiana Mill.) and cherry (Prunus serotina Ehrh.), with a small amount of cedar Juniperus silicicola [Small] Bailey) and southern pines (Pinus spp.).

All mulches (except the GRU utility-pruning mulch) were purchased at garden stores in Gainesville, Florida. Wood frames were filled with each mulch to a depth of 9 cm (3.5 in). To determine color changes, we assessed mulches initially, then quarterly in the first year and again after 2 years using Munsell® Color Charts (1975).

Color Changes

The ability to retain color is often a factor affecting the landscaper's decision on which mulch to use. The six mulches in this study started out with varied colors ranging from pink cypress to the browns of other mulches (Table 1). Cypress mulch retained its pink color for one year. Melaleuca changed from a dark reddish brown to gray and pink within one year. Eucalyptus, utility, and pine-straw mulch all changed to pinkish gray. Pine-bark retained its reddish brown color throughout the year. After 2 years, all of the mulches had grayed. However, pine-bark and cypress retained slightly more of their original color than the others. The utility mulch was categorized as gray while the others had a pinkish hue.

Other studies have recorded this variable graying of mulches. In a six-month study, municipal yard waste began to gray after six months, while cypress, pine-bark and pine-straw all retained their color (Stinson et al. 1990). A study comparing bark mulch to plastic mulches rated bark to have the highest appearance rating after five months (Ashworth and Harrison 1983).

Conclusions and Recommendations

Color retention is an important mulch criteria to some landscapers. It appears from this study that color retention after one year is variable with cypress, pine-bark and melaleuca the best having retained their color in the first year (Table 2). Yet after 2 years, most mulches had grayed with pine-bark and cypress retaining some of their original color.

Of course, this graying is mostly on the surface where the sun has impacted the mulch. If these same mulches are raked, their color will reappear. Raking is one of the solutions to longer color retention. Another solution is to replenish the mulch with a thin layer of new mulch.

In the overall comparison of mulches, mulch color seems to be the most minor with no impacts on the mulch's benefits and with many simple solutions to correct graying mulches.

Literature Cited

Ashworth, S. and H. Harrison. 1983. Evaluation of mulches for use in the home garden. HortScience 18(2):180-182.

Duryea, M.L., R.J. English, and L.A. Hermansen. 1999. A comparison of landscape mulches. J. Arboric. 25:88-97.

Duryea, M.L., J.B. Huffman, R.J. English, and W. Osbrink. 1999. Will subterranean termites consume landscape mulches? J. Arboric. 25:143-150.

Stinson, J.M., G.H. Brinen, D.B. McConnell, and R.J. Black. 1990. Evaluation of landscape mulches. Proc. Fla. State Hort. Soc. 103:372-377.

Tables

Table 1. 

Color of mulches from the beginning of the experiment (0 months) to the end (24 months).

Mulch

Color of mulches from the beginning of the experiment (0 months) to the end (24 months).

0

3

6

9

12

24

Cypress

Pink

Reddish yellow

Pink

Light brown

Pink

Pinkish gray

Eucalyptus

Light reddish brown

Pinkish gray

Pinkish gray

Light gray

Pinkish gray

Pinkish gray

Utility (GRU)

Olive, Very pale brown, Pink

Light reddish brown

Pinkish gray

Very pale brown

Pinkish gray

Gray

Malaleuca

Dark reddish brown

Pinkish gray

Pink

Light gray

Pink

Pinkish gray

Pine-bark

Reddish brown, Light brown

Dark reddish brown

Reddish brown

Brown

Reddish brown

Dark reddish gray

Pine-straw

Reddish brown

Reddish brown

Reddish gray

Light brownish gray

Pinkish gray

Pinkish gray

Table 2. 

Color ranking of mulches after 1 and 2 years.

Color

Mulch

After 1 Year

After 2 Years

Least change

Cypress, Pine-bark

Pine-bark Cypress

Melaleuca

Eucalyptus Melaleuca Pine-straw

Most change

Eucalyptus Pine-straw Utility

Utility

Footnotes

1.

This document is FOR 68, School of Forest Resources and Conservation, UF/IFAS Extension. First published July 1999. Reviewed March 2014. Please visit the EDIS website at http://edis.ifas.ufl.edu.

2.

Mary L. Duryea, associate dean for research and associate director, Florida Agricultural Experiment Station and professor, School of Forest Resources and Conservation, UF/IFAS Extension, Gainesville, 32611.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.