By Carol Sitarski, Master Gardener, Cornell University Cooperative Extension
Contrary to belief, mulch has been around for millions of years as the leaves and plants fell to the forest floor and fields where they decayed. Some curious person began watching what happened during this process and realized that the outcome was excellent weed suppression and an enriched soil which grew beautiful plants. The English word mulch probably came from the German word molsch, which means soft, beginning to decay. Farmers were among the first to use mulches to improve their crops. Within the past hundred years home gardeners and landscapers have begun using mulch for easier gardening and within the last fifty years mulch use has grown by leaps and bounds. Why has this practice become so wide spread now? Two reasons: one is that research has proven the benefits of this practice and the other is the availability of products.
Many different natural and synthetic mulches are available today, but they all provide three basic functions:  reduce soil water loss  suppress weeds  protect against temperature extremes. Characteristics of good mulch include:
- cost; they need to be economical, you would be surprised at all the places that need mulch in your landscape, so keeping the price down is important,
- readily available; this can mean using materials that are at hand (leaves, pine needles) or it can mean a local supplier that has mulch and can deliver in a timely manner,
- is easy to apply and remove; if it isn’t easy, the chances are slim you will continue to do this year after year,
- stays in place; (have you ever put down layers of newspaper and before you could spray them with water they are in your neighbor’s lawn?),
- supplies organic matter to the soil (as mulch decomposes it becomes part of the soil),
- and is free of noxious weeds, insects and diseases.
Selecting the right type of mulch should be considered for what you are trying to protect. Winter mulch is put down to protect woody shrubs and plants to insulate against winters cold and help prevent frost upheaval. Straw, pine needles and shredded leaves are all good for this purpose. It is best to put these down in late fall but before the ground freezes. Summer mulch is usually applied when the soil begins to warm, think mid-spring. It is primarily used for water conservation and weed suppression. Two to four inches of mulch is necessary to be effective.
|Material||Resistance to Compaction||Attractiveness||Resistance to Blowing||Source of Weeds & Disease|
|Relative value of mulches that break down in one to two seasons:|
|Relative value of some persistent mulches:|
|Inorganic mulching materials:|
Sawdust, bark, wood chips and shredded bark will rob the soil of nitrogen unless composted for at least a year. Be sure to add a nitrogen supplement to the soil if these are fresh, such as bone meal.
Low growing ground covers are not technically mulch, however, they can be used as such since they provide the same benefits; such as shading the soil, preventing moisture loss and suppressing weeds. Mulch should not be considered a fertilizer even though some do decay and add to soil value, fertilizer should still be applied to plants that are mulched. Never used mulch before? Included is a link to an online calculator to help you calculate how much mulch your gardens will need. www.lawndepotinc.com/garden-center/mulch-calculator-2/
Photo: Colleen Cavagna