Over the last decade or more, environmentally conscious gardeners have reduced the amount of peat moss they use in their gardens, though the change hasn’t been quick or easy.
I didn’t understand why gardeners should avoid peat until Tom Witwicki, President of the Cumberland County Master Gardeners Association, spoke with the Cape Elizabeth Garden Club last month about why peat use is harmful to the environment and, just as important, how to avoid using.
My wife Nancy and I don’t recall buying peat balls for use in our gardens and outdoor pots, but many people have done so since the early 1900’s. Peat holds water and loosens the soil, improving growing conditions for all types of plants – lawn grass, perennials, shrubs and vegetables.
What we used – and still stock in our basement – is Pro-Mix, a peat-based potting mix that is regularly used as a growing medium for vegetable and flower seedlings, as well as potted plants of all kinds.
This is probably the last pro mix we will buy.
Why is the use of peat harmful to the environment, especially with regard to climate change?
Here is some background information.
The United States uses 1.4 million tons of peat a year, with 70 percent of that coming from sphagnum moss moss in Canada, Witwicki said. The peat that is now being mined comes from bogs that were created during the last Ice Age.
Peat bogs are major carbon sinks, meaning they contain carbon. But when peat in gardens is decomposed or burned – peat is used as fuel in parts of Europe – carbon dioxide is released, which helps trap heat near the earth’s surface.
Some other statistics from Witwicki: One cubic foot of peat contains as much carbon as seven pounds of coal. Peatlands cover only 3 percent of the Earth’s landmass but contain 30 percent of land-based carbon, more than all of the world’s forests. Great Britain wants to ban peat cultivation from 2024.
Witwicki mentioned that the member gardeners’ garden plants sold at the annual Cumberland County Master Gardeners didn’t use peat – which is believed to mark a milestone in the big sale. He said the peat-free sale designation requires an asterisk because while the master gardeners did not use peat when potting their own plants, some of the seedlings sold at the sale may have been grown in a potting soil containing peat.
So what should we use if we can’t use Pro Mix or other peated products? The top choice currently is coir, which is made from leftover coconut shells after the coconut has been processed into various food products. Coconut has a water storage capacity similar to that of peat.
One problem is that coir is sold in fairly large bricks that are almost impossible to cut without a band saw. Witwicki has one, but I don’t. The bricks need to be rehydrated, and if you’re using a whole brick (ours weighed 11 pounds), it takes almost a week for the coir to absorb enough water to be used. The easiest way, and I use that word carefully, is to put the brick in a wheelbarrow and fill the wheelbarrow with water. Once the coconut fiber has absorbed enough water, other ingredients need to be added. To make peat-free potting soil, use 7 parts rehydrated coco coir, 2 parts perlite or vermiculite, and 2 parts compost or vermicompost.
Mined from volcanic rock, perlite helps the soil hold water. Some people – including Nancy in this group – don’t like it because it’s white and doesn’t look like soil. Vermiculite is a siliceous material and is brown or beige in color.
A recipe for a soilless seed mix is eight parts coco, three parts worm droppings, and four parts perlite.
Some pre-mixed potting mixes use coco coir. The best known is called Mother Earth. But you would probably have to buy them online. I have rarely seen them in person.
I have already mentioned that peat bricks are used as fuel in Europe. Nancy and I have two leftover peat bricks after a friend gave us a dozen of them after a trip to Ireland more than a decade ago. We burned a few but preferred the oak we got from fallen branches in our garden.
Perhaps the peat bricks will become heirlooms.
Tom Atwell is a freelance writer working in the garden in Cape Elizabeth. He can be reached at: [email protected]