• Pine straw naturally accumulates under the tree's boughs each autumn.pine cone image by Carol Tomalty from Fotolia.com
  
  Pine straw is simply the thatched collection of dead, fallen pine tree needles. In the American Southeast, the vast natural woodlands of pine trees makes harvesting pine straw easy and makes it an affordable mulch material for the garden. Pine straw decomposes slowly but doesn't contain much nutrition; it also keeps soil pH low (acidic). Pine straw blows around in the wind and isn't the best option to cover slopes or hillsides.
  
  

Compost

• Laura Barron of MyNC.com reports that many municipalities collect yard waste and create various organic compost mixes for use by its citizens. Compost is any decaying organic matter ranging from pure leaf mold from raked autumn leaves to a mixture of grass clippings, leaves, manure, twig fragments and bark chips. Compost decomposes more quickly than pine straw, especially when it's rainy and warm outside, but it provides nutrients for your garden plants and doesn't dry out to become flammable. After first applied, compost imparts an earthy black or chocolate brown soil covering, helping demarcate and accentuate beds in the landscape, too.
  
  

Tree Bark

• Bark from fallen trees is shredded into variously sized particles for use as garden mulch. Pine bark and cypress bark (and wood fragments) are common commodities at garden centers in the United States. Different dyes or textures of bark is available to suit each property owner's budget and taste. Smaller bark particles are dubbed "fines" or "soil conditioner" while large chunks of bark are also available. Size of the bark particles affects whether gushing rain water or wind scatters them. Smaller particles may linger on slopes better than larger pieces. The larger mulch chunks take longer to decompose and need less frequent replacement/application when compared to bark fines.
  
  

Straw

• North Carolina State University states that straw is the least expensive mulch to use, especially for erosion control projects. Shredded straw for use in garden beds is acceptable, but the particles remain susceptible to wind-tossing and the straw's light color may not be aesthetically pleasing to everyone. Straw is made from any type of tall grass--from oats or wheat to meadow grass mixes. A major drawback to using straw is not knowing the composition. Weed seeds linger in straws made from mixed meadow locations and are introduced into the garden if this straw is used as mulch.
  
  

Inorganic Mulch

• Gravel, rock, and rubber nuggets are also options to use for garden bed mulch, but only if the area is not frequently cultivated. Don't use these products in vegetable or flower beds that require annual compost applications or digging and transplanting. The University of Rhode Island cautions the use of inorganic mulches as they are more expensive overall but last longer. Some plastic products may not allow air or water to permeate into the soil for plant roots. Dark colored products absorb more heat from the sun and rock can radiate heat off at night, changing water needs of plants.