HO-60
YARD AND GARDEN
GARDEN MULCHES
E. R. Honeywell
HORTICULTURE DEPARTMENT COOPERATIVE EXTENSION SERVICE PURDUE UNIVERSITY LAFAYETTE INDIANA 47907
Most herbaceous plants, even most shrubs and trees, benefit by a mulch, no matter how hardy they appear to be. Nature's mulch is made of fallen leaves, grasses and litter from various sources. This material finds its way to the garden border, under trees, among shrubs, and affords plants protection. Yet many home gardeners collect this debris and burn it. Too often the passion for neatness sacrifices the welfare of plant materials.
Function of mulches
Garden mulches may be applied for several reasons:
•	To conserve soil moisture by preventing or hindering evaporation.
•	To reduce soil temperatures during extremely hot weather. Mulching has an insulating effect on the soil and absorbs heat, helping to maintain a cooler subsoil.
•	To maintain a comparatively even soil temperature during cold periods. Frozen soil may thaw to the surface under a good mulch. A mulch thus keeps the soil warmer at the surface, preventing injury to roots from a lack of available moisture.
•	To prevent alternate freezing and thawing. Many plants are shallow-rooted with rather delicate, fibrous roots; when the soil is subject to frequent freezing and thawing, many of these roots will be broken or damaged. Heaving can be greatly reduced or prevented by a mulch which reduces the amount of freezing and thawing.
•	To reduce or prevent soil erosion. A mulch of straw or similar material placed on a newly planted lawn or seedbed, or on sloping areas, will help prevent erosion and retain the moisture in the surface soil.
•	To protect fruits and flowers from soil spattered by rain, as in the case of strawberries, tomatoes, chrysanthemums and peonies.
•	To help control weeds. A good mulch may replace frequent cultivations in controlling many kinds of weeds.
•	For a pleasing appearance. Many organic mulching materials, such as peat, weathered, crushed corn-cobs, chopped bark and leaf mold, are dark brown and seem to add character and serve as a good background color for flowers and plant material.
•	To aid in seed germination. Because mulching materials reduce evaporation, help maintain uniform temperatures and prevent erosion, they may frequently be used as an aid to seed germination. Mulching materials should be more freely used for this purpose.
•	To keep soil loose. Organic materials help keep the surface of the soil loose and mellow, because they protect it from the beating of heavy rains. The vegetable fiber that works into the surface also prevents the particles of heavy clay soil from running together or puddling.
•	To add organic matter (humus) to the soil. Humus is a very complex substance and is usually dark brown in color. It develops from, or is the product of, decomposition of plant and animal remains. Humus has three main functions in the soil, each equally important to the home gardener:
Cooperative Extension Work in Agriculture and Home Economics, State of Indiana, Purdue University and U. S. Department of Agriculture Cooperating. H. G. Diesslin, Director, West Lafayette, Ind. Issued in furtherance of the Acts of May 8 and June 30, 1914.