Container Gardening
Nuts and bolts of container Gardening
Bryce Lane's slide show with his soil recipes and other recommendations on container gardening can be found here: Bryce Lane on Container Gardening.
Please enjoy this link for your personal use but do not copy and share elsewhere without contacting Bryce for permission. His address is in the slides.
Environmental Concerns about Using Peat in container gardening?
Much press has been given to whether using peat in the horticulture industry is environmentally sound or sustainable.The use of peat in horticulture is not large compared to that of the forestry and agricultural industries, but it is part of a larger problem. Peat bogs can take hundreds to a thousand years to regenerate. Harvesting peat also disturbs species dependent on the ecosystem of peatlands and contributes -- in some degree -- to global warming as peatlands act as carbon sinks. [1,4,5]. The U.K. is banning use of peat compost. [6]
Post-Symposium correspondence with Bryce Lane examined alternatives to peat in "meatless" soil without diving into the factual basis of the peat debate. If you are concerned about using peat, Bryce suggests experimenting with replacing it with compost/humus. The general formula to start would be:
2 parts Humus/compost (e.g.: bagged, H3 cube, Timberline etc.)
2 parts soil conditioner (e.g. Timberline)
1 part perlite by volume (not by weight)
Other sources suggest replacing peat in containers in part or in whole with byproducts of the agriculture industry: coir -- from coconut shells -- or rice hulls. [1,4,5]. Bark and wood fiber are also recommended. [6]
None of these products completely replicate the value of peat in one area of the horticultural industry -- seed growing. Peat has beneficial bacteria and natural fungicide properties that are especially valued for drainage and minimizing damping off of seedlings. Thus not all sources are on board with abandoning peat for seedlings. [2] Alternatives to peat for seed starting come with many caveats and extra labor recommended. [2,6]
No source found supports using large amounts of peat to amend garden soil. That practice is viewed as wasteful and unnecessary, since plenty of other organic matter will fit the bill, like compost. [2,3]
The majority of the debate centers around using peat as a potting medium. Most sources split between ditching peat entirely in containers or reducing peat use and adding other products (wood based, coir, rice hulls, etc).
Robert Pavlis, at Gardenmyths.com, dives deeply into the subject of peat in potting soil. He questions whether peat really is a non-renewable or endangered resource that should be abandoned in container gardening. He is convinced that alternatives to peat, particularly coconut coir, are as bad or worse overall for the environment, including by contributing to climate change. He suggests sticking with peat for containers for now. [3,4].
Other articles focus more narrowly on the ecosystem of peat bogs. Disturbance of peat bogs contributes to climate change due to release of carbon dioxide. [4,5,6,7] Peat bogs are often referred to as "carbon sinks".
One article claims peat bogs store up to 1/3 of the world's soil carbon, although it is unclear how that number relates to the climate change danger posed by harvesting peat bogs. [5]. Disturbing peat bogs also results in diminution and destruction of species in the peatland environment, like curlews. [4, 5]
All this said, it is hard for a non-climate change expert to fathom from these articles how severe the damage from peat harvesting really is. Moreover, these articles do not studiously compare alternatives to peat, but pass alternatives off blithely as "waste products" without reference to their carbon footprint or other issues. [1-7].
Plus just when you think you've decided what to do, another article distinguishes European peat bogs from Canadian peatlands -- from which most peat in the United States is obtained. Apparently we have barely touched a tiny percent of Canadian peatlands and the Canadians take painstaking efforts to maintain and restore the ecosystems there when they do harvest. [5]
With more reading then, it turns out to be a complex issue that doesn't lend itself to simple answers. It's yet another occasion when a claim must be examined in depth and then the answer lies in the gray area. After all this reading, I'm going to finish up that large block of peat from last year. I might mix then some peat and coir or rice hulls (if I can find any) or do some side by side trials of a peatless mix in containers.
What is certain is that I will keep reading about the concerns about using peat and possible alternatives as the science is delved into more.
Contributed by Liane Schleifer
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