Soil Amendments

Adding organic matter to soil


Soil in some areas is of very poor quality, often being considered 'heavy soil' that is too high in clay content. As a result, good drainage and favorable growing conditions are lacking.


Growing conditions for plants can be improved if the existing soil is amended with organic material to create better "tilth." The most commonly used soil amendments like compost, peat moss, mushroom manure and sand, are described below. Improving the tilth of your vegetable garden will also make the soil "workable" earlier in the year, allowing you to rototill and cultivate the soil sooner.


Installing a raised bed garden planter allows for adding an ideal soil mix right from the start.


Leaf compost is available from municipalities that collect leaves in the fall, sometimes for free (or a nominal fee) if you can haul it yourself. Leaves are usually gathered using large truck mounted vacuums or in biodegradable paper bags. Piles are usually turned-over with large front end loaders periodically to encourage aerobic decomposition. Some municipalities also collect kitchen waste for compost.


Compost provides an excellent means of introducing organic matter into your vegetable garden and flower beds.

Peat Moss (Spagnum Moss)

In most cases, the name is more accurately "moss peat" or "sphagnum moss".  Most of these products originate from peat bogs in Canada and are tightly "baled" in plastic wrappers and sold by the cubic foot.  3.8 cubic foot has been the most commonly used size.  Since peat can hold up to 100-times its weight in water, care should be exercised when lifting peat bales that are wet, to help prevent muscle strains.  Gloves should also be worn when handling peat moss due to possible health problems with Sporotrichosis.

Peat is one of the primary ingredients in the "soil-less" potting mixes (like peat-perlite-vermiculite) used by greenhouses and nurseries.  It is generally free of any destructive plant pathogens which could hinder seed germination and healthy plant growth.  Since peat moss is acidic, countermeasures should be taken when using it with plants favoring a higher ("sweeter") pH.  Soil mixes for growing Rhododendron, Azalea, Pieris japonica, and Mountain Laurel are much improved by mixing-in a 3.8 cubic foot bale of peat moss with every cubic yard of average topsoil.

Even though old-timers used peat moss to topdress lawns after overseeding, that practice is generally not recommended.  When peat moss is dry it is hard to wet, and when it is wet it is slow to dry out.

Mushroom Manure (Mushroom Compost)

Those of us who garden in Pennsylvania are lucky to have a ready supply of "mushroom manure!"  This product begins with horse manure that is cleaned out of stalls at horse farms or racetracks. It is then trucked to a mushroom mine where it is further processed by adding straw and chipped corn cobs among other things.  After being spread in the mushroom growing beds it is steam pasteurized.  Following one crop of mushrooms it is removed from the mine and stockpiled.  It is then transported to landscape supply yards for delivery to garden centers. Mushroom compost for sale at supply yards can vary widely, from fresh light "fluffy" material to older, more decayed black "powdery" material.


"Fresh" mushroom manure used instead of wood mulch around Little Princess Spireas.

Mushroom manure is an excellent mulch for flower beds and as a replacement for straw mulch on new lawns. It can also be mixed 50-50 with topsoil (50% topsoil + 50% mushroom manure) to create great flower-growing media.  If your neighbor grows award-winning flowers, chances are he or she uses mushroom manure as a mulch, or mixes it with the soil in the flower bed.

Mushroom manure can be used as a mulch in place of shredded wood mulch but it should not be used around 'acid loving' plants due to its higher pH. So mushroom manure is the opposite of peat moss, in that it has an alkaline pH. Therefore, countermeasures should be considered when using it around acid-loving plants, such as Rhododendrons and Azaleas.


When using sand as a soil amendment, it is best to use "mason's sand" or "sharp sand", since it will have better drainage characteristics than river sand. Builder's sand has angular edges compared to the more rounded edges of river sand. Sand is often used in "flats" to root ground cover cuttings such as ivy and pachysandra. One big disadvantage of sand in growing containers is its heavy weight.