Podcast #5 – Selling Sustainability

Everyone (including me) hates how the word “sustainability” has been overused and misused. Yet there are some good concepts associated with the word that can help gardeners make rational decisions about products and practices. This week’s podcast deconstructs sustainability into specific actions that gardeners can easily follow:

  • Discovering and nurturing the natural processes that keep your gardens and landscapes healthy and functional
  • Choosing plants and products wisely to conserve natural resources
  • Creating gardens and landscapes that don’t require constant inputs of packaged fertilizers and pesticides

The podcast illustrates each of these points.  First, there’s a research article that demonstrates the benefits of polyculture in growing vegetables.  Next, there’s a critical look at a website presenting a “Sustainable Garden Starter Kit: 10 Must-Have Products for the New Green Grower.” Lastly I dispel the myth of “instant landscaping”, which is code for “long term disaster.”

The interview this week is on building your own garden pond. Dr. Jim Scott (PhD in horticulture), turns his talents to the plumbing, electrical work, and aesthetic disguises needed to build a really great garden water feature. Lucky for me, he also happens to be my spouse!

Jim and Linda try to figure out how many years it took to do a week long project


…cleverly disguise pump system…

…and filter system

Seasonal guests

Permanent residents (the little orange guys in water)

Please let me know what you think of the podcast; you can email me directly or post a comment on the blog. Suggestions for future podcasts are most welcome!


One of the best organic fertilizers out there – at least in terms of how plants respond to it —  is bat guano.  As most of you probably already know, bat guano is made of bat droppings.  What you probably don’t realize is that bat droppings need to be aged for a while in an arid environment before they become guano.  Caves provide the perfect environment for this to occur, and so that is where most bat guano comes from.

Because guano needs to be aged in special surroundings before it is used it is not a rapidly renewable resource.  Instead it’s kind of like peat in that it takes anywhere between decades and thousands of years for the raw material from which it is made to develop into the stuff that we use.  Furthermore, by harvesting bat guano we can actually damage the ecosystems present in the caves from which the bat guano is harvested.  Think about it – bats generally feed outside the cave, so when they defecate inside the cave they are actually bringing new nutrients into the cave – nutrients that other creatures can use.  Whole ecosystems are based on this poo!  So when we harvest bat guano from a cave what we are doing is disturbing a specialized ecosystem – a very unique system.

So am I encouraging you away from bat guano?  No more than I would encourage you to consider reducing your usage of peat – or of oil — or any other non-renewable resource.  I can’t deny that it’s a great fertilizer, but if you want to use an organic fertilizer why not at least consider one that is renewable instead of one that is from a limited resource and which may cause harm to a unique ecological system?

A sustainable resource? Oh, for peat’s sake!

Recently a well-known gardening blog featured a guest posting by a garden writer who made a case for using Canadian sphagnum peat moss as a horticultural amendment.  He defended his preference through “facts” provided by the Canadian Sphagnum Peat Moss Association.
This is kind of like relying on the petroleum industry for the most objective information on the environmental effects of oil spills.  Or the tobacco growers association for data on the effects of smoking on human health.  C’mon now.  We know we should consider the source of our information, right?
This isn’t to say that industries don’t have their own scientists conducting research, or that their research is unreliable.  But to depend on industry talking points alone ignores the vast body of information provided by independent university researchers.
Several years ago I reviewed the scientific literature on the topic of peat as a sustainable resource; that column can be found here as well as in my most recent book (The Informed Gardener Blooms Again).  Rather than repeat what I wrote there, I’ve conducted a quick overview of the research conducted on Canadian peatlands published in the last 10 years.
There are many such articles.  And in general the results are not positive.  Here are some of the highlights (or lowlights):

  • Peat harvesting permanently alters the hydrology of bogs so that natural regeneration is impossible
  • Sphagnum does not easily regenerate on degraded peatlands, causing the sites to become drier over time
  • Species composition of harvested peatlands is not the same as on undisturbed peatlands
  • The mulches used in peatland regeneration decompose and become significant sources of carbon dioxide
  • Natural peatlands are long-term sinks of atmospheric CO2, while mined peatlands increase atmospheric CO2 levels
  • Amphibian populations, already hampered by acid deposition, are further threatened by peat mining
  • Volunteer birch trees on abandoned peat mines accelerate water loss

If we, as gardeners, deliberately choose to use unsustainable natural resources, we need to be fully aware of the consequences.  Unquestioned acceptance of industry talking points lends nothing to the discussion.