Mulch serves many purposes: It keeps down the growth of weeds, serves to keep moisture in the soil, keeps the roots of plants cool during the hot summer months, and gives your garden or landscape a neat, attractive appearance. Most importantly it is an organic material that decomposes and adds organic matter or nutrients to the soil. Types of organic mulch (as opposed to rock) that can be purchased are cedar, hardwood, cypress and pine.
Cedar mulch pros
Cedar mulch is reddish-brown in color and can be found throughout the United States. As mulch it is able to insulate the soil, control soil erosion in your landscape/flower beds, maintain soil moisture and control the growth of weeds. It is also favored for its resistance to decay and its insect-repellent qualities.
Cedar mulch cons
Cedar mulch does not decompose quickly (as hardwood mulch does), and it will therefore not add organic material/nutrients to your soil as quickly as hardwood bark mulch will. This, however, can be a plus if the addition of organic material to your soil is not a concern. Cedar mulch loses its color quickly, turning from reddish-brown to a grey color, and it usually costs more than hardwood bark mulch.
Hardwood bark mulch pros
Hardwood bark (made from the bark of hardwood trees such as oak and hickory) is dark brown in color and will appeal to those who do not want a reddish-brown color in their landscape design. It is lower in cost than cedar mulch, and this seems to be the factor that is most attractive to homeowners. Hardwood bark has the same qualities as cedar mulch when it comes to insulating the soil, controlling soil erosion, maintaining soil moisture and controlling the growth of weeds. It breaks down quickly, so if you want to add organic material to your flower beds quickly, hardwood bark would be the mulch of choice.
Hardwood bark mulch cons
Hardwood bark mulch, although lower in cost, breaks down quickly and will need to be replaced sooner than cedar mulch will. It does not have the insect-repellent quality that cedar mulch has and is believed to attract termites.
If you do a lot of gardening that requires lots of digging in your flower beds, you may not want to add mulch to your garden bed because you would need to push the mulch aside each time you go to dig. If you are using mulch as a pathway or under a swingset, you might want to put down hardwood bark due to the lower cost. If you have budget concerns, then do your homework and compare the costs of purchasing by bulk as opposed to purchasing bags of mulch. Although buying in bulk usually produces a cost savings, it is labor intensive (shoveling the bark into a wheelbarrow to distribute it), and inconvenient if it will tie up your driveway for a day or two until it is distributed.
You will have to weigh the pros and cons of cedar and hardwood mulch. Each has its own characteristics, although they will both do the job when it comes to the basic reasons you are putting down mulch--they will keep the moisture in the soil, they will keep the weeds down, and they both will give your landscape a neat appearance.