Peat Moss Vs. Mulch

As a gardener no doubt you may get confused over the use of one type of product over another. There are different types of fertilizers available. So you need to understand what each contains so that you can make an educated decision on which to use under certain circumstances.

Perhaps you are experiencing confusion over peat moss and mulch. Are they the same? Are they used for the same purposes? What is peat moss and how does it differ from mulch?

What Is Peat Moss?

Peat moss is a substance that is harvested from peat bogs. It is decomposed organic matter that collects in ecological and geological deposits over time. It is not sustainable because the bogs from which it comes are limited in quantity. Moreover, it is harvested from far away places, is compressed into bags and trucked long distances for sale.

A peat bog in Ireland.
(Courtesy: Angela Orlando at

Back in the 1970s and ‘80s, it was commonly used as mulch. Today it is commonly used as a soil amendment. It helps to structure soil and is mixed with potting soils and professional growing mediums. It improves drainage, nutrient availability and retention. However, because it is so decomposed, its benefits to the biology of soil are limited.

It benefits when it is mixed into the soil. It does not serve as a good top dressing because it can be blown away by wind and hardened by rain. However, when incorporated into the soil, it can assist in nutrient availability, but it contains little or no nutrients of its own.

Peat moss holds water and releases it slowly. So it is ideal as an additive with sandy, fast-draining soils. It is also good for dense, clay soils. The peat breaks up the soil’s texture and helps aerate it. This helps plant roots receive the proper amounts of oxygen.

You should be aware that peat moss changes the pH levels of soil, making it more acidic. This is beneficial for plants that thrive in acidic soil conditions, but it could harm plants that thrive in more alkaline soil.

Peat moss is generally more expensive than mulch and is sold by the cubic foot or by the quart. Smaller packages are also available, which are ideal for mixing smaller amounts of potting soil, for mixing into the soil of a small garden, or for container plants.

Although it is not dangerous for the environment, it is not renewable. Harvesting is strictly regulated because peat moss reserves grow on a peat bog about one millimeter a year and removing peat releases a lot of carbon dioxide into the atmosphere.

Peat moss is an ideal seed-starting medium because it doesn’t contain any weeds or weed seeds.

When mixing into the soil, it is advised that no more than one-third peat moss be mixed with two-thirds of soil. If you wish to loosen the top 3-inches of soil, mix 1-inch of peat into the top 2-inches of an existing bed. This creates 3-inches of peat moss and soil mixture. This would be ideal for annual and shallow-rooted plants. However, for deeper-rooted plants including shrubs, mix the peat moss 10-inches to 12-inches into the soil.

Peat moss is beneficial when added to the soil of flowerbeds before entering the growing season. As winter turns to spring, turn the soil until there is a mixture of about 30 percent peat moss and 70 percent garden soil.

Peat moss is also ideal for repairing bare spots in your lawn during the summer. Lay seeds onto the bare spot and cover with peat moss to help the soil retain moisture. Keep the peat moss layer thin, about 1-inch. The peat moss will prevent moisture from reaching the soil if it is layered too thick.

What Is Mulch?

Mulch is any material used to cover soil. Its purpose is to retain water in the soil, suppress the growth of weeds, keep the soil cool, and make the garden bed look more attractive.

Composted mulch.
(Courtesy: Rafael I. Merchan at

Organic mulch is commonly used and besides the advantages described above, it also helps improve soil fertility. Types of organic mulch include:

  • Shredded or Chipped Bark
  • Compost
  • Composted Manure
  • Grass Clippings
  • Newspaper
  • Shredded Leaves
  • Straw

Bark mulch is ideal for spreading around trees, shrubs, and garden beds where digging will be limited. It does not mix well into soil and has to be moved aside to make room for new plants. However, it does last longer than finer organic mulches.

Compost or composted manure can be used just about anywhere as long as it is well composted and free of weeds. It can be used to coat the soil or side dress plants during the growing season for insulation and to slowly release nutrients.

Grass clippings are best on remote areas of a garden where you want to suppress weeds. The clippings have high water content and decompose very quickly. As a result, it can become somewhat slimy and emit an unpleasant odor. Grass clippings also tend to mat down, thus preventing water to get through.

Creating grass clippings mulch with a mulching lawnmower adds fertility to the lawn’s soil. If you prefer to bag the clippings, don’t throw them out unless they are contaminated with weed killer or some other herbicide or pesticide. Untreated grass clipping can be dumped into a compost bin or used to mulch open, unplanted areas.

Newspaper has been used for a number of years to keep plant roots moist, suppresses the development of weeds, and controls soil temperatures.

To use as a mulch in a garden, spread a layer of four to eight sheets of newspaper around the plants. Moisten the sheets to keep them in place. Cover the newspaper with a 1-inch to 3-inch layer of another organic mulch and you shouldn’t see any weeds throughout the growing season.

Shredded leaves can be used as mulch anywhere. And they have an added benefit of luring earthworms that help break down the soil. If you spread a layer of shredded leaves in your garden in the spring before plants spread, the mulch will blend into the garden in short time. Shredded leaves mulch is ideal for woodland gardens. If spread over a vegetable garden in the fall, it will decompose over the winter.

Straw and hay are commonly used on vegetable gardens. They suppress soil and soil-borne diseases from reaching the lower leaves of the plants. Straw decomposes very slowly and will last the entire growing season. It is easy to rake away or work into the soil when the time comes to plant new crops or let the vegetable garden go dormant.

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About Robert Janis

Written by Robert Janis for LawnEq - Your specialists for Lawn Mower Parts and Small Engine Parts. We offer genuine premium OEM parts for Land Pride, Toro and many more dependable manufacturers.