Those of you that have followed The Garden Professors for some time know that Jeff Gillman and I are relentless in our pursuit of gardening myths to explode. Social media – Facebook in particular – seems to be a natural breeding ground for dumb and/or dangerous home remedies that go viral. Most of these have no basis in actual science and are easy to dismiss. Other recommendations may have some science behind them, but a careful review of the literature often shows that the bulk of research does not support that particular practice or product. These ones are trickier to deal with, and nothing has been trickier for either me or Jeff than compost tea.
The two of us have posted extensively on this topic in the last six years: just use the search function over in the left hand column of this blog and type in “compost tea”. You’ll find enough reading to keep you busy for a while. I summarized the state of the literature a few years ago in the now-defunct MasterGardener Magazine and to be honest the accumulated literature hasn’t changed much in terms of generating solid science supporting compost tea use. But its popularity seems to be increasing among landscape professionals and gardeners alike.
I get a lot of questions on compost tea from Master Gardeners in particular, who are bound by their positions as university volunteers to use science-based information. One of their major resources is the state university associated with their program – and recently this has become a problem for WSU Master Gardeners. Because on the Washington State University website you can find one professor who cites the lack of credible, consistent science on compost tea usage and another professor who provides workshops and webinars on making and using compost tea. Master Gardeners are understandably confused about what they can recommend and irritated that their university provides conflicting information. Why, they ask, does the university allow this to happen?
The answer is found in one of the most important values that universities protect: the academic freedom for faculty to speak their minds. Ideally this means that faculty can speak up about topics that are unpopular with university administrators without fear of reprisal, but it also means faculty have a soapbox on pretty much any topic they wish. And that’s whether or not they have any expertise or credibility on that topic. (For a particularly egregious example, one needs look no farther than prestigious MIT who has a research scientist with no expertise in biology or chemistry but who publishes articles in marginal journals linking glyphosate – the active ingredient in Roundup – to just about every known human malady.) Universities tend not step into this fray as it is a slippery slope – who decides what faculty speech should be censured and which should not?
How can Master Gardeners and others decide what information to believe? Well, that’s actually the mission of this blog and our Facebook page and group – to provide the best current gardening science and to help the public increase their scientific literacy skills. Science is not immutable – it advances as credible, published evidence accumulates. When and if compost tea ever becomes a consistent, effective product, we will be the first ones to share that information.