Garden Mulching Revisited
by Tom Rood, Master Gardener

July 24, 2002

Just about a year ago, Master Gardener Sheri Mochamer wrote about using mulches in the garden. Her article is available on the Master Gardener web page: www.cce.cornell.edu/yates/MGIndex.htm. Sheri mentioned the dry conditions of 2001. Here in our area it looks like we are in for another dry gardening season.

Garden plants normally need at least one inch of rain per week and can go into drought stress quickly without it. Watering in place of rain may not be an option if ground water levels continue to drop. Domestic water use then has full priority in the home. Some communities may even issue water restrictions that may not allow lawn and garden watering. Soaker hoses, often made from recycled tires, is one of the best ways to get water down to the root zone where it is needed. If water conservation is needed in your garden this is one option to consider. Overhead sprinklers loose a large percentage of water to evaporation. Shut down the sprinklers for a rest period when puddles are forming. If a rain gauge is not available set out a pie pan near the area being watered with sprinklers. When it is full, that area has received its inch of water.

Mulch is one answer to holding some of the precious soil moisture from evaporation. The simplest garden method is to perform shallow cultivation down the rows of plants. Pull the loose soil around the base of the plants with a hoe. Old timers will recognize this procedure as hilling up or making a dust mulch. It is often done to potatoes and sweet corn. Most other garden plants will benefit as well.

Two of the handiest mulches are green grass clippings and, if there is commercial tree trimming going on nearby, wood chips. However, fresh grass clippings and wood chips can tie-up nitrogen in the soil by the bacterial action breaking the mulch down. Allow the grass clippings to dry before spreading around the plants. Grass clippings should not be applied more than two inches in depth at a time as it thatches into a thick matt. Yellowing of plant leaves is an indication that nitrogen deficiency is taking place. It is easily remedied with a light sprinkling of a fertilizer containing nitrogen. The first number on the fertilizer label is the percentage of nitrogen in its mix. Avoid using wood chips that contain black walnut, butternut or hickory chips. These will contain the chemical substance juglone to which some plants, such as tomatoes, have a very low tolerance. Once wood chips containing juglone have been composted for a year or more they should be ok to use.

Some other things that work as garden mulch are sawdust, leaves, newspaper, straw, old hay and commercial mulches. Sawdust, if fresh, must have a nitrogen fertilizer added to replace lost nitrogen as with woodchips and green grass clippings above. Straw contains some seeds but not as many as old hay. Old hay is best composted before use. If properly composted, the seeds will be destroyed. Newspaper should be soaked with water before applying and laid down in sections 1/4 inch thick. The newspaper is then covered with mulch otherwise it will dry out and blow away making the neighbors very unhappy. Mulch should be built up to a depth of three to six inches to be effective.

Mulch, while holding down water evaporation, will also help reduce weed growth. A disadvantage to using mulch is that it can provide a safe refuge for garden insects such as slugs. One has to make the determination whether to have drought stressed plants or to worry about insect damage. Healthy plants will have a much better chance at survival under insect attacks than stressed plants. And, there are remedies to insects but that is the subject for another Master Gardener article. For all your lawn and garden questions, or if you are interested in becoming a Master Gardener, call the Master Gardeners at the Cooperative Extension office 315-536-5123 leaving your name, question, phone number and a time we may return your call with the results of our research. This is just one small part your Cooperative Extension plays in supporting our community.

Cornell Cooperative Extension Yates Association
Last updated: 7/24/02

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