The Garden Of Oz

The Perils Of Peat Moss

What is Peat Moss?

Peat moss comes from bogs, which are water-saturated, oxygen poor environments. Because of the lack of oxygen and the resulting low level of soil microbes, peat moss is made up of partially decomposed dead vegetation. In colder climates, peat moss is generally comprised of partially decomposed mosses. Partially decomposed tree material is the basis of peat moss in tropical climates.

Unlike finished compost, which is “all good,” peat moss can be good or bad.

The Good Aspects of Peat Moss

Peat moss is readily available at virtually all garden centers. It’s lightweight, and relatively inexpensive. Peat moss is generally sold in bales that contain from 1 to 4 cubic feet of material per bale, and you can buy a large quantity of it for very little money. A 3 cubic foot bag will generally cost about 10 bucks.

Peat moss will dramatically improve water absorption in sandy soils; it will improve air circulation in clay soils; and, it can improve the tilth of both sandy and clay soils.

Peat Moss will usually lower the pH of garden soils, and can be helpful where the soil is too alkaline for the intended crop. Blueberries, which perform much better in acidic soils, will usually benefit from the addition of peat moss. And, peat moss can be used to encourage pink hydrangea flowers to turn blue.

The Potentially Bad Aspects of Peat Moss

As noted above, peat Moss has an acidic pH, generally in the range of 4.4 (a pH of 7 is neutral; higher pH numbers indicate alkaline soils). If your soil is already acidic, adding peat moss will probably make it less productive for most plants (blueberries, azaleas, and other “acid-loving” plants being the possible exception).

Peat moss is also very dusty; in addition to being messy, peat moss can irritate your lungs. The shape of the very small particles is such that the fibers can actually stick to the insides of your lungs for a while … not a very pleasant situation! If you decide to add peat moss to your garden, try to do so on a very calm day, wear a respirator, and till it in as soon as you can.

Uses for Peat Moss

In addition to being used as a soil additive where appropriate, peat moss is the primary component of most “soilless” mixtures that are commercially sold for seed starting and houseplant potting. These mixes usually also contain pearlite, vermiculite, and added nutrients. Many mixes also contain a wetting agent, as dry peat moss – in spite of its ability to hold and absorb water – will initially repel water. If you’ve ever started seeds in a soilless mix, you’ve probably noticed that water will initially stay on the surface of the dry medium. When I use soilless mixes for seed starting, I prepare small batches in a bucket or mixing tray by kneading the water into the mix by hand. Wear a paper or foam respirator – it may look silly, but your lungs will thank you.

Some gardeners have successfully grown tomatoes in bales of peat moss. You can simply cut an opening in the middle of the broad side of the bale, and insert a tomato plant seedling. Of course, since the peat moss is acidic and practically void of nutrients, you’ll need to feed the plant with a good balanced fertilizer.

Peat Moss and the Environment

There has been some ongoing discussion about whether or not the use of peat moss is environmentally responsible. Peat moss is a renewable resource. But, peat bogs are also very efficient as “carbon sinks” and may play an important role in controlling global warming. Well over 90 percent of the peat moss used in the United States comes from Canada, and thankfully, the Canadian Sphagnum Peat Moss Association (CSPMA) emphasizes sustainable harvesting methods. So, it’s unlikely that the bogs will be depleted any time soon.

Peat Moss and Your Compost Pile

Don’t add large quantities of peat moss to your compost pile or bin. It won’t help, and large quantities will probably hurt. You don’t need to obsess about removing the small remnants of peat moss that may still be visible around the root systems of plant material that you add to the compost at the end of the growing season, but a well-maintained compost pile doesn’t need peat moss to perform.

For more information on composting, go to HowToCompost.org.

If you have any comments, I’d really like to hear from you.

OZ Gardener
The Garden Of Oz

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March 4, 2013

By: sherry franklin

thank you i wished i had read your article before i applied ; because no masks were warn during appliacation.

February 22, 2013

By: Linda

Good article except peat moss and sphagnum moss are not really the same. Sphagnum moss (the fluffy green stuff) is renewable but peat moss (crumbly brown stuff) is the dead highly compressed sphagnum moss that is on its way to becoming burnable peat in a few thousand years. Peat moss is NOT a renewable resource. It accumulates at a rate of approx 1mm/year.

February 18, 2013

By: Liz F

Seems to be good gardening stuff, lots of info, easy to read. Thanks!

September 15, 2012

By: linda

Thanks for the heads-up about peat moss. I have a lung condition, and didn't know the effects this is having on me . great article ,keep up the good work.

July 25, 2012

By: joann

I have a question. If peat moss is water repellent
and you add to clay soil what happens if it is very dry, cause clay cracks and if peat moss doesn't allow for water to absorb then what

April 30, 2012

By: GardenerB

Finally! A page to actually answer my questions and give well thought-out information that is not just one sided.

May 4, 2009

By: Ginger

Great article! I didn't know that peat moss stuck to my lungs if I breathed it in. I'll be sure to wear a dust mask when I garden with it...I was wondering why I was breathing weird after planting.

Thanks!!

April 3, 2009

By: homes-n-gardens

Thank you!