Let’s face it, there is a lot of gardening advice out there. Sometimes it can be difficult to tell the good from the bad. We get caught up in doing things “the way they’ve always been done” without asking ourselves if “the way it’s always been done” is really right for our area and what we want to grow. We get swayed by popular fads with little to no basis in science or get mislead by our own preconceived notions about the benefits of certain practices without really looking at the evidence. Here are three popular gardening myths and the truth behind them.

Myth #1: It’s a good idea to “sweeten the soil” with lime each year, especially in the lawn.

Truth: This is often a case of gardeners taking the wisdom of a previous generation and misapplying it, doing things because that’s the way their parents or grandparents did it in their day and it worked well enough for them. The truth is, you don’t know what your lawn needs in terms of “sweetening the soil” without having it tested. If you’re in southeast Michigan, chances are your soil is going to be anywhere from 6.5 (slightly acidic) to 7.5 (slightly alkaline) on the pH scale. Adding lime indiscriminately will raise the pH to a possibly undesirable level. Most plants want a pH in the slightly acidic range and evergreens, magnolias, and many berries will prefer acidic soils. Have a pH test done first and amend the soil to achieve the correct pH for your plants.

Myth #2: Pine needles, pine mulch, and cedar mulch make the soil acidic as they decompose since they come from acid loving plants.

Truth: What’s underground has more effect on your soil than what’s on top. Much of lower Michigan sits atop limestone (in fact, the world’s largest limestone quarry is located at the tip of Michigan’s mitt in Rogers City). Areas with limestone beds are typically neutral or alkaline regardless of what’s decaying on top. Needles and mulches made from acid loving plants will only change the pH level by about 10% at most (eg. from 7.0 to 6.9) so have no fear about planting that spruce or adding a healthy bed of pine bark mulch!

Myth #3: Coffee grounds dumped in the garden are excellent for plants.

Truth: Yes and no. Coffee grounds should be composted with other materials or added as a very thin (1/2in or less) under layer beneath wood mulch. Fresh coffee grounds are phytotoxic (poisonous) to plants and must never come into direct contact with the roots and shouldn’t be used alone as they can cause problems with moisture and soil consistency. Used properly, however, coffee grounds will bind pesticide residues and toxic metals as well as increasing the availability of nitrogen, phosphorous, iron, and zinc. They are not an effective insecticide, however, as is often claimed and will cause reduced germination when used around seeds. And of course, always let your coffee grounds cool before adding them to compost or mulch layers as steaming hot grounds will kill any beneficial bacteria or fungi that may come into contact with them.

So how do you sort out the good from the bad? There are a couple of key things to look for. First, take a good long look at the credentials of both the author and the publication you’re getting your information from. Is it an accredited source that’s peer reviewed? A publication for industry professionals? A gardening hobbyist’s magazine? Beware of so called “pay to play” journals and publications, ones that will publish anything they’re paid to regardless of the author’s background, the veracity of their scientific testing, etc. What is the relevance of the material in question? Does it only apply to specific crops or geographic areas? Do the claims have objective, scientific testing to back them up or are they based solely on anecdotal evidence? How well was the material written? You can tell a lot from spelling and grammar about the quality of work behind the claim. Finally, what biases might the claimants have? What is their goal in giving you this information? Educational? Commercial? Ideological? These kinds of questions can act as a litmus test for the gardening advice you’re bound to get and help you bust some of the more persistent horticultural myths that are out there. Your state agricultural extension is also a great place to start getting advice. In Michigan, this is the MSU Extension.

In the end, remember, gardening should be FUN! Don’t let your quest for good information stop you from getting outside and enjoying your gardening experience. And remember, our trained English Gardens experts are always here to help answer any question you might have when it comes to plants in the landscape, garden, or home.